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HORIZONS System News

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                            Horizons On-Line System News
 Oct 15, 2014:
    -- Mars spacecraft trajectories in Horizons (MAVEN, MEX, MOM, MRO) have 
        been updated for the comet Siding Spring (C/2013 A1) encounter. 
    -- Comet Siding Spring orbit solution #101 predicts a nominal closest 
        approach to Mars-center of 140,750 +/- 530 km (3-sigma) on 2014-Oct-19 
        18:27:31 +/- 11 sec. UTC (3-sigma).  The solution's data-fit includes 
        Oct. 7 comet astrometry from the MRO optical navigation camera and will
        be the last update prior to the encounter with Mars. A small telescope
        is required to see the 10-11 magnitude comet from Earth. An updating 
        "finder chart" is here: http://theskylive.com/c2013a1-tracker

 Sep 22, 2014:
    -- To generate an ephemeris of Rosetta with respect to comet 67P, set the 
        coordinate center to "@1000012". Such comet-relative data is available 
        only over 2014-Jan-1 to present.

 Aug 19, 2014:
    -- ICE/ISEE-3: trajectory has been updated to JPL solution s45 based on 
        the total set of 51 Arecibo angular measurements spanning May 22 to 
        Aug 19. ICE data-sheet contains preliminary encounter reconstruction
        details.

 Aug 11, 2014:
    -- Saturnian irregular natural satellites 619-631, 636-648, 650-652, 65035,
        65040-65041, 65045, 65048, 65050, 65055-65056, along with planet center
        699 have been updated to trajectory solution SAT368 from R. Jacobson 
        (JPL). The solution includes ground-data through early 2014 and all 
        Cassini imaging data through 2013.

 Aug 07, 2014:
    -- Trajectory updates for Earth-orbiting spacecraft derived from JSpOC 
        Two-Line Elements (TLEs) have finally been automated. Trajectories for
        observatories like Hubble, WISE, Swift, SDO, the ISS, XMM-Newton and 
        SPEKTR-R will thus be up-to-date. 
    -- ICE/ISEE-3: No new measurements since July 15. Arecibo signal strength 
        on August 5th suggests the current solution s41 prediction was within 
        ~100 arcsec of actual. ICE may be observable visually at mag. 19-20 
        over the Aug 9-20 interval. Earth close-approach is Aug 9 03:07 UTC, 
        Moon closest-approach is Aug 10 19:26, with uncertainties of ~3 hours.
     
 Aug 05, 2014:
    -- System configuration problem from 21:45 to 06:00 UTC may have prevented
        some types of output return.

 Jul 23, 2014:
    -- ALERT! Those who produce software which uses asteroid and comet SPK 
        files generated by Horizons are strongly urged to obtain the latest 
        SPICE Toolkit, version N0065 or later ...

                   http://naif.jpl.nasa.gov/naif/toolkit.html 

        ... and re-link all software that uses SPK files. The N0065 release 
        contains a new Type 21 ("Extended Difference Lines") SPK reader
        subroutine. In the months ahead, Horizons asteroid and comet SPK file
        production will be altered to generate this improved file type. 
    
        If user software is simply re-linked with the N0065 library, it will 
        automatically have access to the new reader and automatically adapt 
        when the change occurs. If not re-linked, user software will fail 
        when trying to read the new SPK file format. Old (current) SPK files
        won't be affected and will continue to be transparently readable.

 Jun 14, 2014:
    -- Asteroid orbit solutions (644000+ now) have been redone using a refined 
        reference star catalog debiasing approach applied to the angular 
        astrometry.  For most cases, the change in the nominal trajectory 
        should be well within the prior solution uncertainties, though if those
        prior uncertainties were large, the nominal could change noticeably for
        long predictions.

 Jun 05, 2014:
    -- Saturnian system objects 601-609, 612,614 and planet center 699 have
        been updated to solution SAT365 from R. Jacobson (JPL). This
        incorporates Cassini and ground data through May 22, 2014.

 Jun 01, 2014:
    -- The ICE/ISEE-3 trajectory has been updated to JPL solution #6 (s6),
        based on coarse Arecibo plane-of-sky angular measurements 
        (not delay/Doppler).

        The s6 solution should be good enough for near-term pointing, so 
        predicts are available through June 9. The trajectory will be updated 
        and extended as new measurements warrant with future updates noted 
        in the spacecraft's data-sheet.

 Apr 22, 2014:
    -- Version 3.90: Solar system barycenters, Sun, Earth, and Moon have been
        extended to cover 9999 BC - AD 9999.

 Apr 14, 2014:
    -- A planning trajectory for the James Webb Space Telescope (JWST) is  
        available.
    -- A portable/programmable version of the JPL/Horizons database of 
        asteroids and comets ("DASTCOM5") may be retrieved here:
           
             ftp://ssd.jpl.nasa.gov/pub/xfr/dastcom5.zip
             unzip -ao dastcom5.zip

       The file is updated as often as hourly (between 30-32 minutes after
       the hour) to capture database changes.
      
       Unzipping will create a sub-directory with a file called
       "./dastcom5/doc/README.txt", explaining usage. 

       Other directories contain FORTRAN source code for a reader library 
       and application program called "dxlook" which accesses the database 
       interactively or with scripts.

       The DASTCOM5 package is intended for programmers comfortable with 
       UNIX/LINUX/MacOSX command-line usage.

 Mar 31, 2014:
    -- Cassini Mission reference trajectory has been updated.

 Mar 10, 2014:
    -- Congratulations to AMSAT-DL/Bochum for their reacquisition of the
        ICE/ISEE-3 spacecraft:

        http://www.amsat-dl.org/index.php/news-mainmenu-97/199-ice-satellite-received-in-bochum?start=1

        "On March 1st and 2nd, 2014 radio amateurs were able to detect the 
        beacon signal from the retired NASA deep space probe ICE (International
        Cometary Explorer) at the Bochum Observatory (Germany) ..."

 Feb 20, 2014:
    -- A trajectory is now available for the ISEE-3/ICE spacecraft. Launched in
        1978 and encountering L1, Moon, comet Giacobini-Zinner and Halley, the 
        mission was terminated in 1997. The transmitter was left on. Last 
        detected in 2008, the spacecraft may encounter the Earth in August of 
        2014. Trajectory accuracy is unknown; if you find it optically or 
        detect its radio signal, let us know!

 Feb 03, 2014:
    -- A trajectory for ESA's Gaia spacecraft (orbiting Earth-Sun L2) is now 
        available, with nominal predicts through 2019. Will be updated as
        possible.

 Jan 31, 2014:
    -- Saturnian satellites 610,611,615-618,633-635,649,653 have been
        updated to the SAT363 solution from R. Jacobson (JPL). This
        includes two separate solutions for Daphnis (635) over the
        1949-2010, 2010-2050 intervals.

 Jan 08, 2014:
    -- Uranian satellites 701-705,715 and planet center 799 were updated to
        the new URA111 solution from R. Jacobson (JPL).
    -- Uranian satellites 716-724 were updated to the new URA112 solution
        from R. Jacobson (JPL).

 Dec 30, 2013:
    -- Pluto satellites 901-905 and planet center 999 have been updated to new
        solution PLU043 from M. Brozovic (JPL). This solution is the subject
        of a paper submitted to the New Horizons issue of Icarus.
    -- Saturnian satellites 601-609,612-614,632 and planet center 699 have been
        updated to new solution SAT360l from R. Jacobson (JPL). 
    -- Saturnian satellites 619-631,636-648,650-652,65035,65040-65041,65045,
        65048, 65050,65055-65056 have been updated to use the new SAT362
        solution from R. Jacobson (JPL).
         
 Dec 12, 2013:
    -- Neptunian satellites 809-813 and planet center 899 were updated to 
        the new NEP086 solution from R. Jacobson (JPL).

 Dec 02, 2013:
    -- Jovian satellites 501-504, 514-516 and planet-center 599 have been 
        updated to the new solution JUP310 from R. Jacobson (JPL), based on
        all data reported through 2013.

 Nov 27, 2013:
    -- Comet ISON (C/2012 S1): There has been an approximately 40 arcsecond 
        drift relative to ballistic ISON predicts over the last three weeks. 
        If your observations have pointing requirements sensitive at that 
        level, be sure and obtain predicts based on the latest solution. Orbit
        solutions since Nov 22 (s49) have been estimating non-gravitational 
        accelerations due to out-gassing and that is reflected in the predicts.

 Nov 26, 2013:
    -- The XMM-Newton X-ray observatory, an Earth-orbiting telescope, is now
        available over 1999-2013.

 Nov 14, 2013:
    -- The MAVEN spacecraft trajectory (NASA launch to Mars) is now available.
        Weather currently looks 60% for the planned Monday November 18 launch.
        If delayed, the trajectory will be updated here.

 Nov 08, 2013:
    -- India's Mars Orbiter Mission (MOM) trajectory is now available.  The 
        spacecraft will be maneuvering in Earth orbit until achieving hyperbolic
        escape ~Nov 30. Predicts are from navigation tracking solutions at JPL.

 Nov 06, 2013:
    -- Version 3.83:
        * If phase angle exceeds 120 degrees, output visual magnitude is now 
           rounded off to the nearest degree to indicate the reduced accuracy
           of the IAU asteroid H-G model at such high phase angles. Previously,
           output of the value was suspended and an "n.a." marker displayed.
        * S-T-O angle (observer table quantity #24, the approximate phase 
           angle) was restored as a solo quantity; true phase angle (phi) and
           phase angle bisector were moved to new quantity #43.
       
 Oct 08, 2013:
    -- Check out the real-time Horizons-based finder charts at TheSkyLive: 

        http://theskylive.com/

    -- Juno spacecraft will have an Earth flyby Oct 9, 2013 at 19:21 UTC en 
        route to Jupiter. Departure from Earth-Moon space should be readily 
        observable, but the approach may be a challenge to pick up optically, 
        being close to the Sun (~25 deg) and at a high phase angle (>120 
        degrees) until a few minutes before encounter. 

        The spacecraft's closest approach occurs while in Earth's shadow
        for 19 minutes off the southern coast of Africa. The ground-track
        then heads northeast toward India before turning west to cross the
        Mediterranean and southern Europe.  North American visibility
        starts the same evening/night of Oct 9/10.

        Magnitude estimates are iffy, but it should be visible for the next
        couple days or so after the encounter, probably brighter than 20th
        magnitude until ~Oct 11-12. 

 Oct 01, 2013:
    -- Routine hardware maintenance the morning of Thursday Oct 3 will take the 
        following addresses off-line for ~2 hours:  

        ssd.jpl.nasa.gov 
        neo.jpl.nasa.gov  
        iau-comm4.jpl.nasa.gov

       Services unavailable during the time will include: 

        Horizons, ispy/fov (field of view identification), NHATS accessibility
        list, SBDB (Small-Body Database), Sentry risk page listing, SkyMorph,
        small-body look-up, SPK file generation, orbit diagrams, the radar
        astrometry database, and everything else served off the above addresses.

 Sep 25, 2013:
    -- The LADEE spacecraft trajectory is available again; history and 
        predicts through science mission, including maneuvers.

 Sep 24, 2013:
    -- The Venus Express (VEX) spacecraft trajectory has been updated based on
        data provided by ESA.

 Sep 22, 2013: 
    -- The LADEE spacecraft trajectory will be unavailable until gaps in 
        in the trajectory data are remedied.

 Sep 12, 2013:
    -- Jovian satellites 501-505,514-516, and Jupiter planet center 599 were
        updated to the JUP309 satellite orbit solution from R. Jacobson (JPL)

 Sep 01, 2013:
    -- A portable version of the JPL/Horizons database of asteroids and comets 
        ("DASTCOM5") may be retrieved here:
           
             ftp://ssd.jpl.nasa.gov/pub/xfr/dastcom5.zip
             unzip -ao dastcom5.zip

       It is updated as frequently as hourly, reflecting new discoveries and 
       the latest JPL orbit solutions. Up to 142 fields per object (including
       osculating orbital elements) are defined in the binary, direct-access 
       database, though not all fields are populated at this time.

       Unzipping the archive will create a sub-directory and file called
       "./dastcom5/doc/README.txt" that explains usage. Other directories 
       contain FORTRAN source code for a reader library and an application 
       program called "dxlook" which  can be used to access the database 
       interactively or with scripts.

       The DASTCOM5 package is intended for programmers comfortable with 
       UNIX/LINUX/MacOSX command-line usage.

 Aug 30, 2013:
    -- The nominal trajectory for the LADEE spacecraft is now available. 
        Select by specifying "LADEE" or by SPK ID "-12".

        Launch of the 160-day NASA mission to the Moon is scheduled for 
        Sep. 07, 03:27 UTC. Trajectory will be updated here as warranted.

 Aug 29, 2013:
    -- Ephemerides for Sun & Earth-Moon Barycenter L1, L2, L4, and L5 dynamical
        Lagrange points have been updated for consistency with the DE431 
        planetary ephemeris. The change relative to DE405 was generally less 
        than ~1.6 km. The available time-span was extended to cover 1900-2150.

 Aug 26, 2013:
    -- Herschel trajectory update from ESA now includes 8 optical measurements 
        obtained after the final burn (through July 1, 2013).

 Aug 24, 2013:
    -- Irregular Jovian satellites (objects 506-513,517-550, 55060-55076) have 
        been updated to use the JUP300 solution from R. Jacobson & M. Brozovic
        (JPL).  This includes all observations through 2012.

 Aug 23, 2013:
    -- Horizons has been updated to use the rotational models of the 2009 IAU 
        convention, as given in the "Report of the IAU Working Group on 
        Cartographic Coordinates and Rotational Elements: 2009". 

        Take note of this change if results are used for Juno or New Horizons
        analyses.

        In particular, the change reflects redefinition of the Pluto North 
        Pole. In the prior implementation [IAU2006], used by Horizons from 
        2010-Mar-11 to now, the Pluto pole was:

          R.A.= 312.993 , Dec.=  6.163 , P.M.= 237.305 - 56.3625225*d

        It is now:

          R.A.= 132.993, Dec.= -6.163, P.M.= 302.695 + 56.3625225*d

        The Jupiter rotation rate was 870.5366420 deg/day [IAU2006]. It is 
        now adopted as 870.5360000 deg/day [IAU2009].

 Aug 13, 2013:
    -- Version 3.81:
        Supports non-gravitational acceleration models for asteroids, including
        non-standard g(r) for simulation or proxy models. Covariance mapping
        for such cases will come later.
    -- The unnumbered asteroid orbits have been recomputed in the system of
        DE431 with 16 perturbing asteroids. Comets will be done case-by-case.

 Aug 05, 2013:
    -- Numbered asteroid orbit solutions are being recomputed with DE431.
       This will take several days. Unnumbered asteroids will be done later. 
         - Asteroid and comet solutions now include perturbations from 16 large
           asteroids (formerly was Ceres-Pallas-Vesta only). Small-body 
           perturbers considered in small-body integrations now include:
              1 Ceres, 2 Pallas, 4 Vesta, 10 Hygeia, 3 Juno, 6 Hebe, 7 Iris,
             15 Eunomia, 16 Psyche, 29 Amphitrite, 52 Europa, 65 Cybele, 
             87 Sylvia, 88 Thisbe, 511 Davida, 704 Interamnia
         - These perturbing objects will now also be flagged in Horizons
            close-approach tables, when integrating other small-bodies.
         - The default small-body maximum integration span is increased 300 
            years, to cover 1600-2500. Ancient comets are allowed longer spans,
            since they are of low accuracy anyway.
         - Planetary system barycenters have been extended to cover 8000 BC 
            through AD 9000. Planet centers limits remain bounded by the 
            natural satellite solutions, where there is one.
         - Orbit uncertainties will now be available for all asteroids,
            not just NEAs and comets.

 Jul 31, 2013:
    -- Version 3.80:
        Horizons will be transitioning from DE405 to the new DE431 planetary 
        ephemeris solution over the next couple weeks. 

        DE431 (Folkner, Williams, JPL) is a substantial improvement in the 
        solar system dynamic model, incorporating high-precision tracking of 
        spacecraft during the last 20 years with model refinements to provide
        a substantial reduction in dynamical uncertainties of objects 0-10,
        301,399.

        DE431 also reflects the redefinition of the astronomical unit by the
        IAU to a permanently fixed value of 149597870.700 km. The au was 
        previously a solved-for parameter in the planetary ephemerides.

        Small-body orbit solutions will be redone for consistency with the 
        updated solar system dynamics. Numerical changes at varying levels 
        (generally small) can therefore be expected in Horizons predictions. 

        More information will be provided as the changes are implemented.

 Jul 30, 2013:
    -- The final LCROSS trajectory update prior to lunar impact (2009) has
        been incorporated and is now available. 

 Jul 15, 2013:
    -- The trajectory solution for newly discovered Neptunian satellite
        2004N1 is now available. Select using designation "2004N1" or "814".
        Orbit solution NEP087 (R. Jacobson, JPL).

 Jul 12, 2013:
    -- Pluto system ephemerides (901-905,999) have been updated to solution 
        PLU042 (M. Brozovic, JPL). Recently discovered and newly named Styx 
        (905, 2012P1) was also added.

 Jul 08, 2013:
    -- Subsequent to end-of-helium condition on April 29, the Herschel mission 
        performed a burn to empty fuel tanks. The spacecraft is currently 
        tumbling without attitude control. 

        A trajectory prediction extending over 40 years was provided by the 
        ESA flight dynamics team, based on a revised orbit solution 
        incorporating the best estimate of the drain burn, but without 
        post-burn ranging or optical. An updated prediction is expected to
        be released in the future.

 May 28, 2013:
    -- Saturnian satellites 619-631,636-648,650-652,65035,65040-65041,65048,
        65050,65055-65056 were updated to the new SAT361 orbit solution from
        R. Jacobson (JPL).

 May 16, 2013:
    -- The Mercury rotation model was updated to used the IAU 2009 model.
        This will produce a ~0.2 degree shift in longitude due to a slightly
        different prime meridian reference.

 Apr 26, 2013:
    -- Small-body uncertainties may not be available for some objects for 
        a few days while transitioning to new databases goes on in the 
        background. However, covariance matrices will be back soon, this 
        time for all small-bodies, not just NEO's and comets.

 Apr 12, 2013:
    -- Saturnian satellites 601-609,612-614,632 and planet center 699 have
        been updated to new solution SAT359L (R. Jacobson, JPL), fitting
        Cassini tracking data through March 2013.

       Satellites 610-611,615-618,633-635,649,653 have been updated to the
        SAT357 solution.

 Apr 03, 2013:
    -- Version 3.75:
       * Local apparent hour angle has been added to observer tables as 
          requestable quantity #42. Values run from -12 to +12 angular hours, 
          with 0 corresponding to the observer's zenith meridian (object 
          transit). Negative values are angular hours UNTIL transit; positive 
          values are angular hours SINCE transit.
       * Hour angle can also now be used to suppress observer table output when 
          outside a specified limit (as with prior airmass, elevation angle, 
          daylight, and solar elongation angle limiter-options).  

          For example, a cut-off value of "1.5" will output table data only 
          when the LHA is within +/- 1.5 angular hours of zenith meridian.

          The e-mail control file variable for this is LHA_CUTOFF= 'X', where 
          X is a decimal angular hour 0.0 < X < 12.0. To restore output (turn 
          OFF the cut-off behavior), set X to 0 or 12.0.

 Mar 18, 2013:
    -- Version 3.74:
       * The heliocentric orbit true anomaly angle has been added as an option 
          to observer tables as quantity #41.
       * True phase angle (phi) and phase angle bisector (PAB) direction have 
          been added to the output of observer table quantity #24, formerly 
          only "S-O-T" angle (which is retained). For an otherwise uniform
          ellipsoid, the time when its long-axis is perpendicular to the PAB 
          direction approximately corresponds to the lightcurve maximum of the 
          body (maximum brightness). PAB is discussed in Harris et al., Icarus 
          57, 251-258 (1984).

 Mar 06, 2013:
    -- The total apparent magnitude estimate for comet C/2011 L4 (PanSTARRS) 
        has been altered to use the Yoshida model. Nuclear magnitude continues
        to use the IAU model.

 Feb 13, 2013:
    -- Comet & asteroid SPK trajectory files (only) produced Feb 8-12 UTC 
        inadvertently had relativity dynamics turned off. High precision 
        applications over long time spans may want to regenerate any SPK
        files requested during that time. ASCII observer, vector, osculating 
        element, and close approach tables were unaffected.

 Jan 29, 2013:
    -- Version 3.71:
        * Added Earth oblateness acceleration to Horizons default propagation
           dynamical model for all small bodies approaching Earth. Has been 
           part of the orbit solutions since the 2011 MD case in July 2011.

 Jan 23, 2013:
    -- Version 3.68:
        * Updated to use the high-precision Earth orientation model for 
           center-of-disc planetographic/geodetic latitude and longitude when 
           Earth is the observing target (observer table quantity #14). 
           Outputs more significant figures in that situation. Previously 
           used a low-precision (~0.1 degree) IAU model when "looking down".
        * Removed unnecessary warning messages output in some circumstances
           when loading user macros.

 Oct 26, 2012:
    -- Jovian satellites 55072-55075 have been updated to trajectory solutions
        JUP294 based on observations through 2012.

 Oct 24, 2012:
    -- Pluto system ephemerides (bodies 901-904,999) were updated to solution
        PLU031 from R. Jacobson (JPL), a fit to all available data and 
        presented at the 2012 DPS meeting.

 Oct 19, 2012:
    -- The Mariner 2 trajectory has been added to Horizons. In 1962, it was
        the first spacecraft to successfully encounter another planet (Venus). 
        Thanks go to John Anderson from the Mariner 2 navigation team (JPL,
        retired) for producing and providing the trajectory.

 Oct 11, 2012:
    -- The EPOXI spacecraft trajectory has been updated to include the final
        planned 1.8 m/s maneuver on Oct 4, setting up the 2020-Jan-4 flyby 
        encounter with 2002 GT.

 Oct 02, 2012:
    -- Version 3.66:
        Comet ISON (C/2012 S1) visual magnitude predictions have been disabled 
        near perihelion since the standard IAU magnitude model is not good for
        objects that close to the Sun. The situation is driven by observational
        data and will be reviewed as more measurements are reported.

 Sep 28, 2012:
    -- Updated Mars system (bodies 401, 402, 499) to MAR097 solution from
        R. Jacobson (JPL), as presented at AAS/DDA meeting 6-10 May 2012.
        http://adsabs.harvard.edu//abs/2012DDA....43.0914J
        
 Sep 18, 2012:
    -- Version 3.65
        * Comet 2P/Encke visual magnitude calculation was altered to use the 
           Yoshida model. This should substantially improve the returned
           value for this periodic comet during its inactive phases.
        * Fixed a bug preventing email return of large output files that are 
           split into parts
    -- A bug in the email server's "batch" queue handling was fixed. Certain 
        conditions were resulting in users occasionally receiving multiple 
        copies of output in response to a single request. 

    Both email issues were relics from last year's transition to the new 
    server platform operating system. They probably puzzled a few people 
    since then, so don't hesitate to mention problems.

 Sep 07, 2012:
    -- Newly recovered Jupiter satellite 2000J11, now with an ~11 year 
        data-arc, is now available on Horizons. Access by designation 
        '2000J11' or with provisional JPL ID number 55076. Orbit solution 
        by M. Brozovic, R. Jacobson (JPL).

 Aug 03, 2012:
    -- Final Horizons update for the MSL trajectory prior to 2012-Aug-06 
        ~05:17:49 UTC landing is available. The navigation team reports 
        the trajectory solutions are stable and on target with no need 
        for a contingency TCM-5 (TCM= Trajectory Correction Maneuver).

        With down-leg light-time of 13.8 minutes, confirmation of landing
        will arrive at Earth after ~05:31 UTC.

 Jul 31, 2012:
    -- Venus Express and Mars Express trajectories have been updated based
        on ESA trajectory release.

 Jul 23, 2012:
    -- Another update to the latest MSL landing trajectory from the navigation
        team.

 Jul 16, 2012:
    -- Pluto system ephemerides (objects 901-904,999) have been updated to 
        the new PLU022 solution from M. Brozovic (JPL), which includes an
        albedo dynamic model.

       Saturn system ephemerides (objects 619-631,636-648,650-652,65035,
        65040-65041,65045,65048,65050,650555-65056) have been updated to 
        the new SAT354 solution from R. Jacbson (JPL). This is a fit to 
        Earth-based data through 2012 and Cassini observations of Bestla.

 Jul 08, 2012:
    -- The MSL spacecraft trajectory has been updated, now with predicts
        through EDL to Mars landing Aug 6 ~05:18 UTC.

 Jul 05, 2012:
    -- The Dawn spacecraft trajectory has been updated, now with a reference
        planning trajectory for the Ceres orbital phase.
 
 Jun 27, 2012:
    -- Version 3.60:
        Asteroid and comet SPK files produced by Horizons are now Type 1 
        difference lines instead of the former Chebyshev polynomials (Type 2).
        The comment format within the output files has changed but the change 
        in data structure should otherwise be functionally invisible to users. 

        The change enables faster production of generally higher fidelity 
        SPK trajectory files comparable in size to (or smaller than) prior 
        Chebyshev files.

 May 03, 2012:
    -- Version 3.52:
        Small-body integration error over epochs distant from the present
        was reduced. This might be noticeable at the 10^-7 AU level for some 
        ancient (B.C.) comets, so is generally much less than the uncertainty 
        of such orbit solutions (improved noise).

 May 01, 2012:
    -- The MESSENGER spacecraft trajectory was updated (after two years on
        predicts...) and is expected to be updated monthly now until end of
        mission.

 Apr 25, 2012:
    -- The positive leap-second to be introduced June 30 (in accordance with 
        the IERS) is being applied to Horizons' output UTC for dates after that
        time.  ftp://hpiers.obspm.fr/iers/bul/bulc/bulletinc.dat

 Apr 02, 2012:
    -- NOTICE: For ~2 hours beginning at 06:00 UTC on Wednesday April 4, 
        there will be brief, intermittent losses of external connectivity 
        between JPL/Horizons and the Internet. The losses of connectivity 
        are estimated to be about 2-6 minutes each. It is unknown how many
        there will be during the 2-hour window.  

 Mar 09, 2012:
    -- Saturnian satellites were updated to use SAT353 solution from 
        R. Jacobson (JPL): 610-611,615-618,633-635,649,653.

 Mar 06, 2012:
    -- Version 3.48:
        Fixed a problem in which Horizons was computing relativistic light
        deflection due to a planetary mass for coordinate center observers 
        internal to that mass. Thanks to Joel Parker for noticing the anomaly
        that resulted.

 Feb 03, 2012:
    -- Recently discovered irregular Jovian satellites 2011J1 and 2011J2 have
        been added with temporary IDs of 55074 and 55075. The trajectory 
        solutions are based on JUP291 from R. Jacobson (JPL).

 Jan 26, 2012:
    -- The SOHO spacecraft trajectory was updated. Note the prior coverage of 
        2011 was a prediction now replaced with reconstruction.

 Jan 13, 2012:
    -- Saturnian satellites 601-609,612-614,632, and planet center 699, have
        been updated to the new SAT351 solution from R. Jacobson (JPL). This
        is based on Cassini spacecraft tracking data through the end of 2011.

 Nov 28, 2011:
    -- The Hubble Space Telescope trajectory has been updated to fill database
        gaps in which lengthy interpolations degraded trajectory accuracy.
        Thanks to Dave Clark for detecting the problem.
 
 Nov 22, 2011:
    -- Mars Science Laboratory (MSL) launch trajectory is now available.
        Select using spacecraft ID -76, or "MSL".  Launch is scheduled for 
        Saturday Nov 26 15:02 UTC (start of window).

        The trajectory here starts after the second-stage Centaur separation,
        about 49 minutes after launch. If launch is delayed, the trajectory
        will be updated here as soon as possible.

 Nov 20, 2011:
    -- Apollo landing site coordinates have been updated to those of
        Davies & Colvin, "Lunar coordinates in the regions of the Apollo
        landers", JGR v105, pp. 20277-20280 (2000). The prior values were
        from an older, less robust reference. Thanks to Ron Burman for 
        pointing this out.

 Nov 10, 2011: 
    -- Jovian satellites 2010J1 and 2010J2 have been updated to new trajectory
        solution JUP286 from R. Jacobson (JPL).

 Nov 09, 2011:
    -- Phobos-Soil_1 and Phobos-Soil_2 TLE-based trajectories have been added,
        replacing "Phobos-Soil". These two objects were found to be on 
        trajectories similar to the Earth-orbiting parking trajectory of the 
        original spacecraft. It is thought the engine firing did not occur.

       Efforts are underway to recover the spacecraft and reattempt the 
        interplanetary injection phase if possible. However, battery power 
        may be depleted in the next few days (~Nov 11-15).

       To obtain Earth shadow entrance/exit (eclipse) information for the 
        objects from Horizons (as with Hubble & ISS), select an object as   
        the target, then the Moon as coordinate center ("@301"). Then 
        request "observer table" quantity #12, "satellite angular separation
        and visibility".

       A marker code of "/u" will be displayed when the object is in umbral
        eclipse. You would probably want to use a fine time-step of 1 minute
        or less when generating such information. 

 Nov 04, 2011: 
    -- Daytime object 2005 YU55 was successfully acquired by Goldstone radar.
        The orbit solution has been updated to #72, based on the delay-Doppler
        measurements, and can be retrieved here. Trajectory uncertainties are
        reduced ~75% with these initial measurements.

       A 2nd orbit radar-update (prior to optical visibility) is expected to be 
        available around Nov 7 00:00 UTC, reducing uncertainties further.

 Nov 03, 2011:
    -- We plan to have an orbit solution update for 2005 YU55 based on 
        Goldstone radar astrometry by about Nov 4, 20:35 UTC. This daylight
        object won't be visible until after it's Nov 8 0.85 lunar-distance
        approach.
    -- Spektr-R was updated from an official trajectory (not TLEs) provided
        by Russia's IKI.

 Oct 12, 2011:
    -- The Phobos-Soil trajectory was extended to Mars encounter.

 Oct 10, 2011:
    -- The Phobos-Soil spacecraft's planning trajectory for Nov 8 launch from
        Baikonur (Russia) is now available. The Russian Space Research
        Institute has expressed interest in astrometry and imaging of Earth 
        departure, especially engine burns to occur over South America.

 Oct 04, 2011:
    -- Spektr-R space telescope trajectory was added
    -- Hubble Space Telescope trajectory was updated
    -- GRAIL's second stage trajectory was updated

 Sep 14, 2011:
    -- GRAIL A & B trajectories been updated with post-launch data-fits.

 Sep 10, 2011:
    -- GRAIL launched at the second window of the day; the relevant trajectory
        prediction files are now in Horizons.

 Sep 08, 2011:
    -- Pre-launch trajectories for Moon-bound GRAIL-A, GRAIL-B and the second 
        stage (GRAIL-SS) are now up on Horizons for the Saturday Sep 10 launch
        window #1.

        If launch is delayed, the on-line trajectories will be updated as soon 
        as possible.

 Sep 02, 2011:
    -- Saturnian satellite 2010J1 and 2010J2 trajectories have been updated
        to a new solution fit to data through Aug 2011 from M. Brozovic (JPL).
    -- Cassini reference trajectory has been updated.
    -- ARTEMIS trajectories are back and current as far as they go. 
        A prediction interval will be added in a week or so.
    -- Hope to have GRAIL prior to launch, but it is still pending.

 Aug 15, 2011:
    -- Pluto system ephemerides (planet center and 4 satellites) have been
        updated to solution PLU021 (M. Brozovic, JPL)

 Aug 09, 2011
    -- Telnet screen sizing on the new server has been fixed. Horizons now also
        dynamically recognizes window size changes. 

       For those accessing by script, the TERM= "no-resize-vt100" environment
        variable isn't used anymore. A subset of RFC 854 and 1073 standards 
        has been implemented. This means an initial control-byte negotiation
        occurs. This should be invisible to your script, if you are letting 
        telnet handle the connection.

 Aug 01, 2011
    -- Welcome to the new server. The SunFire V250, in service since 2004, 
        fades to black.

       One still-unresolved issue affects telnet users, preventing automatic 
        initial screen sizing. 

        Until fixed, you may have to manually tell the system your screen 
        dimensions (if the 24 x 79 default isn't OK) by typing in the command: 

                           tty {rows} {columns} 

        ... at the main "Horizons>" prompt. For example, "tty 33 101" tells
        the system your window has 33 rows and 101 columns. 

 Jul 27, 2011
    -- Hardware upgrade means HORIZONS will be unavailable for a short time 
        early next week. When we come back, we should be >10x faster.

       Nominal planning is for downtime Monday Aug 1 within the span 
       16:00-20:00 UTC (~ 9 am to 1 pm west coast Pasadena time in the US). 
       Probably a sub-interval of that span, if no surprises.

       Addresses affected are "ssd.jpl.nasa.gov", "neo.jpl.nasa.gov", and 
       "iau-comm4.jpl.nasa.gov". All functions they provide will be temporarily
       unavailable.

 Jul 21, 2011
    -- Newly discovered Pluto satellite, provisionally designated
        S/2011 (134340) 1 and reported in CBAT 2769 is now available based 
        on orbit solution by M. Brozovic (JPL). Access on Horizons using 
        ID code "904".

 Jul 18, 2011
    -- The pre-launch Juno spacecraft trajectory has been updated for the 
        August 5 opening of the launch window.
    -- A post-capture trajectory for the Dawn spacecraft at Vesta is now 
        available.

 Jun 17, 2011
    -- Version 3.40:
        Output-stepping based on angular motion (instead of time) can now 
        handle cases with user-specified elevation angle limits (rise/set).
         
 May 28, 2011
    -- Jupiter satellite solution JUP282 (R. Jacobson, JPL) is now used for
        bodies 506-513,517-550, and 55060-55073. 

        Satellites 2010 J1 and 2010 J2, two recently discovered Jovian 
        irregulars, are now available with the temporary numbering of 
        55072= 2010J1 and 55073= 2010J2.

 May 25, 2011
    -- System was down for ~5 minute fan replacement

 Mar 18, 2011:
    -- Saturnian satellite trajectories for 610-611, 615-618, 633-635, 649, and
        653 were updated to use the new SAT342 solution from R. Jacobson (JPL),
        reflecting Cassini spacecraft tracking data through November 2009.
    -- The Horizons telnet interface was altered to support name searches for 
        small-bodies having an apostrophe in the name. E-mail requests can 
        enclose the look-up command in double-quotes:

        COMMAND= "O'Connell;"
    
 Feb 15, 2011:
    -- WISE STATUS: No further updates to the Earth-orbiting WISE trajectory 
        will be made on Horizons. The last communication pass will occur from 
        11:35 a.m. to noon (PST) on 17 Feb 2011. During this pass, the s/c 
        transmitter will be turned off, ending mission operations and 
        navigation support. TLEs may be obtained from USSTRATCOM or other 
        public sites to derive future spacecraft location data.
    -- Constellation boundaries have been updated to use two more digits of
        precision for sub 0.1-arcsecond specification. 

 Feb 10, 2011:
    -- The MESSENGER spacecraft trajectory was updated for the March 18
        Mercury orbit insertion.

 Jan 31, 2011:
    -- Both the NExT spacecraft (formerly Stardust Bus) and 9P/Tempel 1 comet
       trajectories have been updated for the 200 km Tempel 1 comet flyby on 
       2011-Feb-15 04:39:16 UTC.

       To obtain an ephemeris relative to the comet Tempel 1 navigation 
       solution (s11025p_s89g), set center as "@1000093".  Conversely, to 
       obtain an ephemeris of the comet relative to NExT s/c, set target 
       "1000093" and set center "@next".

       The above will access precomputed trajectories as released by the NExT
       navigation team.  If you aren't concerned with encounter details, you
       can request 9P/Tempel 1 from the comet database as usual for a 
       numerically integrated version and predicts over longer time-spans.

       The current best global solution is K053/25, with an epoch of 2003.
       This, or follow-ons to come, should be used for non-spacecraft purposes. 

       There is a solution #91 (epoch 2010) adequate for the 2011 NExT 
       encounter, but less good than K053/25 for times away from that epoch.
       Also, FYI, earlier solution K051/22 has an epoch of 2006, and was a 
       fit keyed to the 2005 Deep Impact ecnounter but is not as good for 
       times away from that event as K053/25 or #91.
       
 Dec 17, 2010:
    -- The Planet-C (Akatsuki) trajectory was updated to reflect the failure 
        to achieve Venus orbit insertion Dec 7. No new trajectory updates
        are expected here, though they may resume in future years if there is
        further spacecraft activity.

 Dec 13, 2010:
    -- The Swift Earth-orbiting gamma-ray burst observatory has been added.
        Future trajectory updates will be at user request.

 Dec 06, 2010:       
    -- Most NEO orbits in Horizons were recomputed based on debiased optical
       astrometry as described Icarus 210 (2010) 158-181, "Treatment of star 
       catalog biases in asteroid astrometric observations", Chesley SR, 
       Baer J, Monet DB. 

       The refinement aims to compensate astrometric measurements for small 
       systematic errors (generally 10's of mas level) in background star 
       catalog positions. This usually amounts to position changes for the
       new solutions well within the noise-level of prior orbit solution 
       uncertainties.

 Oct 22, 2010:
    -- Uranian satellites 716-724 and planet center (799) have been updated to
        the latest satellite solution URA095 from M. Brozovic (JPL).
       Neptunian satellites 809-813 have also been updated to new solution
        NEP085 from M. Brozovic (JPL).

 Oct 16, 2010:
    -- Updated to latest Saturnian satellite solution SAT314 from R. Jacobson 
        (JPL). Objects affected are: 619-631, 636-652, 2004S7, 2004S12, 
        2004S13, 2004S17, 2006S1, 2006S3, 2007S2, 2007S3.

 Sep 09, 2010:
    -- Satellite solution JUP230 was extended to span 1600 to 2500 for objects 
        Io (501), Europa (502), Ganymede (503), Callisto (504), Amalthea (505) 
        and Jupiter planet center (599)

 Aug 19, 2010:
    -- If you don't get a response from the e-mail batch system, it is likely 
        your e-mail program isn't set to send "plain-text" ASCII (7-bit). 
        A helpful guide to suitably configuring various mailers is here:

              http://stagecraft.theprices.net/nomime.html

       Modern e-mail sw increasingly assumes it is communicating with other
       systems like itself, so automatically encodes outgoing e-mail with font 
       codes, formatting symbols, and MIME attachments.  An elaborate front-end 
       is needed to interpret all this, which Horizons does not yet have. For 
       example, it may seem that your command file clearly says
   
           EMAIL_ADDR= 'you@your.computer.com'

       ... but your e-mail software, if not set appropriately, reworks it such 
       that it arrives here looking like

           EMAIL_ADDR =3D =E2=80=98you@your.computer.com=E2=80=99=20

       ... which Horizons can't interpret, hence can't send an error message
       back to, hence no response. The issue is being looked at, but for now
       the simplest fix is if users handle it on their end by setting their
       e-mail software to send ASCII 7-bit plain-text (no MIME).

 Aug 02, 2010:
    -- DAWN spacecraft trajectory has been updated. Chandra, Herschel, Planck, 
        and WISE are updated regularly (weekly or monthly), the others as 
        requested or necessary.
       
 Jul 12, 2010:
    -- Kepler spacecraft trajectory updated, including predicts to 2015.
       Uranian satellites Perdita, Mab, and Cupid were extended to 2050
        (same URA074 solution).

 Jun 30, 2010:
    -- USAGE NOTE: to produce a close-approach table using the e-mail "batch" 
        interface, set MAKE_EPHEM= 'YES' and TABLE_TYPE= 'APPROACH'. 

              ftp://ssd.jpl.nasa.gov/pub/ssd/horizons_batch_example.long

        ... has been updated to indicate this.

 Jun 28, 2010:
    -- The Rosetta spacecraft trajectory was updated for the flyby of asteroid
        21 Lutetia on Saturday July 10 @ 15:44:45 UTC (event time), at a 
        distance from Lutetia center of ~3230 km with a speed of 15 km/s. 

 Jun 24, 2010:
    -- The final EPOXI trajectory release from JPL navigation prior to Earth 
        flyby is now in Horizons. The closest approach will be 2010-Jun-27 
        22:03:48 UTC, 36859 km over the mid South Atlantic Ocean, closer to 
        Antarctica than South America or Africa.

 Jun 12, 2010:
    -- The final Hayabusa trajectory prediction is now available for the Jun 13
        return to Earth (Australia). Lighting is not favorable, but observers 
        in the Maldives should have a good view just after sunset (and of the 
        spacecraft too).

 May 28, 2010:
    -- Spacecraft trajectories have been added for Planet-C (Venus Climate
        Orbiter, VCO), and the ARTEMIS-P1 and ARTEMIS-P2 spacecraft headed
        to Earth-Moon L1/L2.

 Mar 18, 2010:
    -- The Mercury rotation model was updated to use the published version of
         Margot, J.L., (2009). "A new orientation model for Mercury,"
         Celestial Mechanics and Dynamical Astronomy, v.105, no.4, pp. 329-336.

 Mar 11, 2010:
    -- Updated to use the IAU 2006 rotational models in "Report of the 
        IAU/IAG Working Group on cartographic coordinates and rotational 
        elements: 2006."

 Feb 23, 2010:
    -- A trajectory for Lunar Reconnaissance Orbiter (LRO) spacecraft is now
        available. Spacecraft ID is -85.

 Feb 03, 2010:
    -- The interplanetary planning trajectory for spacecraft Hayabusa's return 
        to Earth (June 2010) is now available. Entry/descent/landing trajectory
        is not available at this time.

 Jan 20, 2010:
    -- Pluto system (901-903,999) has been extended to cover 1900-2051
        with the same PLU017 solution.
       Jovian satellites and planet center (501-505,514,599) have been 
        extended to cover 1900-2100 with the same JUP230 solution.

 Jan 15, 2010:
    -- Mars system (401,402,499) ephemerides have been updated to new solution
        MAR085 (R. Jacobson, JPL) as described in Astronomical Journal (AJ), 
        139 (2010) 668-679.

 Jan 13, 2010:
    -- The Pluto ephemeris is currently PLU017 (indicated on output) -- since
        the 2007-Jun-20 announcement for Nix and Hydra satellite updates.

 Dec 17, 2009:
    -- Jupiter planet (599) and satellites 528-538 were updated to orbit 
        solution JUP269; satellites 539-549 were updated to JUP268, and 
        provisional objects 55060-55071 updated to JUP270. "Herse" (550),
        formerly known only as S/2003 J14, was newly numbered and named under 
        JUP270. All solutions are from R. Jacobson (JPL) who comments 
        "Merry Christmas" [ed.: indeed]; some provisional (5-digit) number 
        assignments were switched around, so it is best to access using the 
        object designation.

 Dec 16, 2009:
    -- The initial post-launch WISE spacecraft trajectory is now available 
        (Earth orbiting).

 Dec 14, 2009:
    -- The SOHO spacecraft trajectory (near L1) is now available, beginning 
        with 2008-Jun-1. Spacecraft ID is "-21". Select it as target using 
        that number or its unique name ("SOHO").

        SOHO can also be used as an observing site by picking a target
        (i.e., "Sun") and then a coordinate center of "@-21" (or "@SOHO").

 Nov 24, 2009:
    -- Unidentified object 9U01FF6 has been added to Horizons. It may be
        accessed under that designation or the unofficial SPK ID 9901885.
        The object is thought to be artificial and a piece of debris, based
        on trajectory response to solar radiation pressure.

 Nov 07, 2009:
    -- Version 3.35a
        Fixed a bug that caused no output when using calendrical output 
        stepping to step by month into a non-existent range of date labels 
        (i.e., the Gregorian calendar switch-over point in October 1582).

 Oct 28, 2009:
    -- Rosetta spacecraft trajectory update for Nov 13 Earth flyby.

 Oct 19, 2009:
    -- Kepler trajectory updated to reflect last several months of tracking
        data, with predicts to 2013.

 Oct 07, 2009:
    -- Final LCROSS pre-impact update for Horizons.
    -- Cassini reference trajectory updated.

 Sep 29, 2009:
    -- LCROSS spacecraft trajectory has been updated to model the impact 
        targeting maneuver TCM-8 planned for tomorrow, Sep 30, 2009 @15:00 UTC.
        Further trajectory update(s) are expected in the days ahead.

 Sep 28, 2009:
    -- MESSENGER trajectory update from APL for tomorrow's Mercury flyby and
        gravity-assist: 2009-Sep-29 21:56 UTC at 228 km altitude.

 Sep 25, 2009:
    -- Jupiter planet-center (599) and satellites 539-549, 55050-55053,
        55055-55061, and 55063-55064 have been updated to new solutions 
        JUP266 and JUP267 (JPL, R. Jacobson) and extended in time (1900-2099).

 Sep 09, 2009:
    -- Recent monthly and since-inception usage counts:
          Horizons usage summary 2009-Jul-15 to 2009-Aug-15
          Connections:                 Products:
            Telnet          13073         Telnet          32056
            WWW             49664         WWW             93226
            E-mail           4400         E-mail           8683
                                          SPK obj/fil       119/118
            ---------------------         ---------------------
            Total(month)    67137         Total(month)   134084
           >TOTAL(Oct96)  8453875        >TOTAL(Oct96) 13264926

 Sep 04, 2009:
    -- LCROSS, WISE, Chandra, MEX, VEX, Herschel & Planck spacecraft - updated.

 Sep 02, 2009:
    -- MEX and VEX spacecraft trajectories have been updated ... and should be 
        more routinely now, thanks to Jose Luis Vazquez-Garcia at ESA.

 Aug 17, 2009:
    -- Saturnian satellites 601-609, 612-614, 632-634, 649, 653, and 
        barycentric shift vector 699 for planet center have new solutions 
        SAT317XL, SAT321, and SAT323 (R. Jacobson, JPL) which also cover 
        an extended interval from 1600-2600 A.D.

 Aug 14, 2009: 
    -- The Ulysses spacecraft trajectory has been updated to reflect all 
        tracking data through the final pass 2009-Jun-29.  A predicted segment 
        extends thereafter to 2050. Thanks to Mark Ryne (JPL Navigation) 
        for putting this together. Way to go Ulysses!  What a trip.

 Aug 10, 2009:
    -- Trajectories for Chandra, HST, GALEX, and the ISS were updated today.

 Aug 04, 2009:
    -- Cassini (-82) reference trajectory has been updated through 2017.

 Jul 09, 2009:
    -- A missing term in the new Venusian photometric model implemented 
        2008-Oct-17 was restored. This error primarily affected the magnitude 
        calculation for Venusian phase angles greater than 163.6 degrees. 
        Thanks to Dr. Manfred Gottwald for pointing out the problem.

 Jul 01, 2009:
    -- Planck trajectory updated for July 3rd L2 injection burn.

 Jun 30, 2009:
    -- LCROSS updated based on navigation fit including post-launch data.

 Jun 18, 2009:
    -- The Moon-fated LCROSS mission is currently go for 2009-Jun-18 21:12 UTC 
        launch (tomorrow). 
       The trajectory has been updated accordingly in Horizons (based on 
        navigation team planning), for those who want to track it, or avoid 
        confusing it for an asteroid in Earth vicinity. 
    -- Herschel spacecraft trajectory updated.

 May 08, 2009:
    -- Newly named/numbered Saturnian satellite Aegaeon (653), formerly 
        S/2008S1, has been added to Horizons. 
    -- EPOXI trajectory updated, as were Herschel and Planck (both coming up 
        on launch, ~ May 14).

 May 06, 2009:
    -- L4 & L5 Sun-Earth-Moon Lagrangian points are now available. L1 & L2
        were also extended in time to 2100 AD.

 Apr 28, 2009:
    -- A pre-launch trajectory for the LCROSS lunar impacting spacecraft has
        been added. It will be updated before and after launch.
        
 Mar 27, 2009:
    -- Orbit solutions for natural satellites Triton (801), Nereid (802), 
        Proteus (808) and Neptune itself (899) have been updated to solution 
        NEP081 (Jacobson, JPL), based on measurements reported through 2008 
        (and described in a forthcoming Astronomical Journal paper).

 Mar 25, 2009:
    -- Due to routine building electrical maintenance, the following systems
        or tools will be unavailable Mar 28 12:00 UTC to Mar 29 01:00 UTC: 

          Horizons, Sentry, SkyMorph, SBDB, ispy ...
        
        ... and any other tools provided by addresses

          ssd.jpl.nasa.gov, neo.jpl.nasa.gov

 Mar 20, 2009:
    -- Kepler trajectory was updated; there was an under-burn on the 
        third-stage booster, so the trajectory & prediction has been revised 
        to reflect post-launch tracking and the achieved trajectory.
    -- A reference trajectory for the Kepler 3rd stage booster, based on a 
        little radar from a few hours after launch, is available (ID -134381).
        If you see it, let us know.

 Mar 06, 2009:
    -- STEREO-A and STEREO-B spacecraft trajectories updated.
    -- Horizons/SkyMorph/ssd/neo sites will be down for 15-20 minutes on 
        Mar 10 ~17:30-18:30 UTC, for scheduled maintenance.
 
 Mar 03, 2009:
    -- Hubble, Galex, and Chandra trajectories are up-to-date.

 Mar 02, 2009:
    -- A pre-launch Kepler trajectory has been added to Horizons. First launch
        opportunity will be March 7 03:48 UTC. Kepler is a telescope designed 
        to detect changes in star brightness due to objects having diameters 
        several thousand km or larger crossing in front of the star.

 Feb 13, 2009:
    -- The Dawn spacecraft trajectory has been updated. There will be a Mars 
        close approach of 3945.4 km on 2009-Feb-18 00:28:00 UTC (~549 km
        above 107.56 deg W, 25.65 deg N).

 Jan 21, 2009:
    -- Pre-launch planning trajectory has been added for the WISE spacecraft.

 Jan 10, 2009:
    -- Final NExT trajectory update prior to 15527 km Earth flyby 2009-Jan-14 
        19:32:38 UTC.

 Dec 09, 2008:
    Updated trajectories for upcoming spacecraft flybys:

    -- EPOXI trajectory updated for 2008-Dec-29 21:39:57 UTC Earth encounter.
        49828 km from the center of the Earth, occurring above 221.39 deg. E., 
        -49.44 deg. latitude (south).

        This is 13:39:47 local standard time zone, so close approach is in 
        daylight over the South Pacific ocean, between southern Australia and 
        southern South America.

        Prior to the close approach, declination starts at -23 deg (Dec 28), 
        decreases to -30 deg. (Dec 29 00:00 UTC), then decreases to more than 
        -80 deg by 19:40 UTC, then increases through the 21:40 UTC encounter 
        and beyond, reaching -5 deg 2008-Dec-30 00:00 UTC, then +53 deg. 
        2008-Dec-31 00:00  UTC.

    -- NExT trajectory updated for 2009-Jan-14 19:28:34 UTC Earth encounter.
        15486 km from center of the Earth, occurring above 245.2 deg E.,
        +30.4 deg (north).  This is about 244 miles southwest of Phoenix, 
        where it will be daylight at 12:28:34 MST.

        It will be at a northerly declination of +33 to +34 deg in Jan 1-12, 
        move to +36 Jan 14, then to more than +70 deg just before the 
        encounter, then drop toward the southern southern sky in the minutes 
        after the encounter (at 19:40 UTC, declination is +8 deg; at 
        19:50 UTC, -8 deg).

 Nov 14, 2008:
    -- Mars Express (MEX) trajectory is available again. Hubble Space Telescope
        Trajectory was also updated.

 Oct 28, 2008:
    -- The Mars Express (MEX) trajectory has been disabled, at least 
        temporarily, while a more efficient way of encoding the trajectory 
        kernel is implemented to improve access time. 

 Oct 21, 2008:
    -- Mars Express (MEX) and Venus Express (VEX) spacecraft trajectories were 
        updated to include the orbital phases to date.
    -- GALEX Space Telescope trajectory added ("Galaxy Evolution Explorer")

 Oct 17, 2008:
    -- Version 3.34d
        Visual magnitude calculations for Mercury & Venus now use the updated
        models described in Astronomical Journal, 129:2902-2906 (Hilton, 2005).
        
 Sep 25, 2008:
    -- Mars (499), Phobos (401) and Deimos (402) trajectories were updated to
        use the new MAR080 solution (Jacobson, JPL). This is a km-level change
        which reflects inclusion of Mars Express tracking data, new 
        ground-based data, and an improved model of the effect of Phobos 
        longitude libration.

 Sep 11, 2008:
    -- More network maintenance Sat Sep 13 7:00-11:00 PDT (00:00-04:00 UTC) 
        means sporadic or no connectivity to Horizons, Sentry, SkyMorph, and 
        the ssd.jpl.nasa.gov and neo.jpl.nasa.gov web-sites during that 4 hour
        interval.

 Sep 04, 2008:
    -- JPL network maintenance Sat Sep 6 7:00-11:00 PDT (00:00-04:00 UTC) 
        means sporadic or no connectivity to Horizons, Sentry, SkyMorph, and 
        the ssd.jpl.nasa.gov and neo.jpl.nasa.gov web-sites during that 4 hour
        interval.

 Aug 11, 2008:
    -- Version 3.34a:
        BARYCENTRIC osculating element output (only) was altered to better 
         support users propagating two-body elements with software outside of
         Horizons, such as TNOs with respect to the solar system barycenter. 
         The mass parameter ("GM") used to encode state vectors for output as 
         orbital elements with respect to a barycenter now includes all 
         ephemeris masses. 

         Previously, only masses interior to the target-body/main-belt were 
         included for barycentric element output cases.

         Unchanged are BODY RELATIVE orbital elements (heliocentric and 
         planet-centered orbital elements) and n-body integrations (state 
         vectors, observer tables, SPK files, and close approach tables).

 Aug 07, 2008:
    -- Cassini reference trajectory updated.

 Jul 25, 2008:
    -- Horizons computed its 10 millionth ephemeris on July 17 at 00:34:22 
        Pasadena time, at the request of an anonymous user in Australia.
        "Wahoo ..." says the boss. Look out Mardi Gras.

 Jul 21, 2008:
    -- Uranian satellites 716-724, and planet center 799 solutions were updated
        to URA090, which is based on measurements reported 1984-Jun-1 to 
        2006-Oct-22.

 Jul 07, 2008:
    -- Saturnian satellites 601-609,612-614,632, and planet center 699 
        solutions were updated to SAT288, which is based on all current 
        tracking data. The available trajectories span 1800 to 2200.

 Jun 27, 2008:
    -- The trajectory for "NH" (New Horizons spacecraft) has been updated.

 Jun 07, 2008:
    -- Version 3.33d:
        Minor update to allow calendrical output STEP_SIZE units of "months" 
        or "years". 

        If your start date is 2008-Jun-7, and output is requested to be 
        monthly, the resulting ephemeris will always output on the 7th of the
        month.  Similarly, for a 2008-Feb-29 start date having yearly 
        step-sizes, output will occur only on subsequent Feb 29 dates.

 May 28, 2008:
    -- The Phoenix spacecraft landing site on Mars is now selectable as an
        observing site ("phx@499"). 

                               Longitude(deg)  Latitude(deg), altitude (km)
           areocentric system:  234.250778E,     68.218830N
           areographic system: -234.250778E,     68.451043N , -1

        The altitude above is estimated from a global elevation profile.

        Be aware that most public reports give areocentric latitude coordinates
        for the site with longitude increasing positively to the EAST. This is 
        a "new" standard convention for Mars. Prior to ~2002, all maps and 
        coordinates were instead areographic latitude with longitude increasing
        positively to the WEST (i.e., east longitude was negative), in accord 
        with the IAU convention for Mars and other planets. 

        Horizons continues to use the areographic convention (EAST is negative).
        Thus, the areocentric landing coordinates disseminated have been 
        converted to areographic for use here. If you are comparing with a Mars
        map, you should determine which system the map uses. Good luck.

        http://planetarynames.wr.usgs.gov/TOCmarsmain.html

    -- Trajectories for Saturnian satellites 610-611, 615-618, 633-635 and 649, 
        have been updated based on all measurements (including Cassini 
        spacecraft) available though January 2008.

 May 25, 2008:
    -- Version 3.33a
       TLIST has been extended to permit up to 10000 discrete times (e-mail
       interface). This is an increase from 200. The web interface has a 
       lower limit (currently 15 times).

 May 20, 2008:
    -- Cassini trajectory updated.

 Apr 25, 2008:
    -- Hubble trajectory updated (... and 18th anniversary of its deployment).

 Apr 22, 2008:
    -- Version 3.32e (minor change):
        At the request of the Herschel project, subject headers for e-mailed 
        small-body ephemerides (only) have been changed to include the primary 
        SPK ID number of the target object.

 Apr 17, 2008:
    -- Saturnian satellites (619-631,636-648,650-652, 2004S7, 2004S12,
        2004S13, 2004S17, 2006S1, 2006S3, 2007S2, 2007S3) have been updated
        to new orbit solutions SAT295, SAT296, SAT297, SAT298.

 Apr 11, 2008:
    -- Neptune satellites (801-813) and planet center (899) solutions have 
        been updated based on all reported measurements through the opposition
        of 2007: NEP076, NEP077, NEP078 are the solution names.

 Apr 07, 2008:
    -- Herschel spacecraft pre-launch trajectory was updated. 
    -- Saturnian satellites 601-609 and planet center solutions were updated
        to SAT286, based on all current tracking data, which provides an 
        interval now spanning 1600 to 2600.

 Apr 02, 2008:
    -- Juno spacecraft pre-launch trajectory added. Launch isn't until 2011 ...

 Mar 17, 2008:
    -- Dawn spacecraft trajectory updated through 2015 ... this low-thrust
        mission has substantial flexibility in timing and path (2 month
        "uncertainty" in arrival time). So the reference trajectory is 
        approximate for future dates and will eventually be replaced with 
        something shorter but based on future tracking data. Past is based
        on navigation solutions from tracking data.
    -- Stardust/NExT trajectory extended for new Tempel 1 follow-up mission.

 Mar 14, 2008:
    -- STEREO A & B spacecraft trajectories updated.

 Feb 29, 2008:
    -- Planck spacecraft trajectory updated.

 Feb 27, 2008:
    -- Galileo spacecraft trajectory updated with a new and improved 
        reconstruction segment.

 Feb 07, 2008:
    -- The Mercury rotation model was updated based on radar observations
        reported by Margot et al., Science 316, 2007, and a 2007-Dec-2 memo:  

         alpha-0 (RA J2000) = 281.0097 -0.0328T
         delta-0 (DEC J200) = 61.4143 - 0.0049T
                          W = 329.548 + 6.1385025d

       ... where T is time in Julian centuries (36525 days) from J2000 epoch,
       and d is interval in days (86400 SI seconds) from J2000 epoch, with the 
       J2000 epoch being JD 2451545.0 Coordinate Time (2000-Jan-1.5)

 Jan 10, 2008:
    -- Mars (499), Phobos (401) and Deimos (402) ephemerides have been
        extended 25 years to 2050. Same MAR063 solution.

 Jan 08, 2008:
    -- The MESSENGER trajectory has been updated for the Jan 14 (19:05 UTC)
        200.6 km (planned) altitude Mercury flyby and gravity assist.
    -- The Stardust trajectory has been extended back to the 1999 launch.
    -- Clementine lunar orbit insertion and mapping phases have been added.

 Dec 27, 2007:
    -- As per the IAU Working Group on Planetary System Nomenclature 
       "The spelling of the saturnian satellite Erriapo has been changed 
        from the dative to the nominative case: Erriapus."

 Dec 20, 2007:
    -- The EPOXI spacecraft trajectory was updated for the ~21943 km Earth
        flyby Dec 31 19:29(:21) UTC.

 Nov 13, 2007:
    -- Procedural change:

       For spacecraft trajectories tied to a specific small-body solution,
       request small-body CENTERED output by specifying the coordinate
       center >using the SPK ID<, not name. 

       For example, the Deep Impact flyby with respect to the official 
       encounter solution for Tempel 1 (K051/17) is now specified by giving
       a coordinate center of "@1000093".

       Formerly, one could specify "@Tempel", but this caused confusion for 
       people unrelated to the flight-project trying to look up the current 
       globally best solution for Tempel 1.

       BACKGROUND EXPLANATION IF YOU DON'T KNOW WHAT THIS IS ABOUT:

       In certain instances Horizons has to provide access to more than one 
       orbit solution for the same object. For example, Tempel 1 solution 
       'K051/17' is encounter-specific, based on the spacecraft OpNav images,
       but degrades with time away from the encounter data-arc. Meanwhile, 
       the small-body database continues to provide new, continuously updated
       solutions (as additional ground-based optical data is reported) that 
       are better over extended periods of time and additionally provide the 
       covariance needed to compute uncertainties.

 Nov 06, 2007:
    -- Version 3.32b (minor change)
        * Observing sites within 0.5 km of the poles may now be specified.
        * MPC packed-designations can be searched without having to specify 
           a "DES=" keyword. For example, entering "J50D00A;" at the main 
           prompt works now.

 Nov 02, 2007:
    -- The Rosetta trajectory has been updated for the Earth flyby to
        occur Nov 13 20:57 UTC at 0.83 Earth radii above surface.

 Oct 22, 2007:
    -- Saturnian satellite orbits updated: 610-611,615-617,618,633,634,635
       New Saturnian satellite available : 649 (Anthe = S2007S4)

 Oct 19, 2007:
    -- Trajectory added for EPOXI mission (formerly Deep Impact) to comet
        103P/Hartley 2.
    -- Dawn spacecraft trajectory extended to December 2007

 Sep 28, 2007:
    -- Dawn trajectory has been updated to reflect the 14 minute launch delay.
        Any images or tracking? Let us know!

 Sep 24, 2007:
    -- Dawn trajectory updated for new Sep 27 launch schedule.
    -- Saturnian satellites 601-609, and Saturn planet center (699) have been 
        updated to solution SAT261, and extended in time over 1600-2600.
 
 Sep 21, 2007:
    -- The Cassini reference trajectory has been updated for dates after
        2007-Sep-18.
    -- The Dawn trajectory from 3rd stage separation to +80 days is now
        available for the Sep 26th launch date.

 Sep 08, 2007:
    -- Uranian satellites 706-715 updated to new solution URA086 (first 
        update since 1996).

 Aug 25, 2007:
    -- Version 3.32:
        Observer-table range-rates for quantities #19 & #20 (Sun and observer)
        have been changed to be projections of the velocity vector on the
        light-time corrected (only) state vector. Explanations printed at the 
        end of the ephemeris have been made more descriptive for these two 
        quantities.

 Aug 03, 2007:
    -- The Phoenix trajectory was updated for the new Aug 4 launch.

 Aug 02, 2007:
    -- The solution for Uranus planet-center (799) and satellites 701-705
        were updated to URA083 (first solution update since Horizons 
        initialized in 1996).
 
 Jul 07, 2007:
    -- Dawn was rescheduled for September launch to avoid impacting the
        upcoming Phoenix launch (Mars lander) as a result of accumulated and
        expected delays. Dawn has been temporarily removed from Horizons 
        pending new trajectory data.

 Jul 07, 2007:
    -- Dawn launch is now no earlier than July 15.

 Jul 06, 2007:
    -- Dawn launch now July 9.

 Jul 05, 2007:
    -- Dawn's launch has been pushed back a day to July 8 due to lightning
       conditions during second-stage fueling. Weather seems iffy for the 8th
       also (60% chance of being out of bounds), so expect push-backs.
       Trajectory on Horizons has been updated for July 8 launch.

 Jul 02, 2007:
    -- The Dawn spacecraft trajectory is now available. Nominal launch is 
        July 7.

 Jun 20, 2007:
    -- Recently discovered satellites of Pluto (Nix & Hydra) are now available.
    -- The Cassini mission reference trajectory was updated.

 Jun 19, 2007:
    -- Initially ambiguous Earth-orbiting object "6R10DB9" reached perigee 
        2007-Jun-14. The trajectory has been updated to include Goldstone
        Doppler measurements. 

 Jun 08, 2007:
    -- The Phoenix trajectory (first launch opportunity) is now available. 
        The launch window opens Aug 3 and runs for 22 days.

 May 23, 2007:
    -- The Spitzer Space Telescope trajectory has been lengthened to include 
        a potential extended "warm Spitzer" mission.

 May 18, 2007:
    -- When generating an ASCII ephemeris table for 99942 Apophis for times 
        AFTER the record-close 2029 encounter, minimize error accumulation by 
        doing it in two parts: the first part from 2005 forward, the second for
        any times significantly (years) prior to 2005.

        To generate an ASCII table from 1900-2099 (for example), Horizons 
        starts at the 2005 solution epoch and numerically integrates back 105 
        years to 1900. It then reverses direction, integrating forward from 
        1900 to 2099 to produce the table in chronological order.

        By the time it gets to the 2029 close encounter, it has integrated
        105 + 105 + 24 = 234 years, compared to only 24 years if you do it
        in two parts.  For other objects, the error accumulated in the 
        sequential numerical integrations calculations is negligible.  But the 
        record-close 2029 encounter (5.96 Earth-radii) amplifies the 
        computational noise for Apophis, degrading predictions after 2029 for
        such (effectively) long-term propagations. However, the error is
        still less than the intrinsic uncertainty in Apophis' location due
        to astrometric measurement, so it is still "in the noise".
 
        Close-approach tables are not affected by this hysteresis, being 
        generated in both directions from the solution epoch. Other objects 
        are not significantly affected by this, lacking such close approaches.
        For example, 1862 Apollo can be integrated back 100 years, then forward
        100 years with the initial state recovered to the sub-km level through
        24 planetary encounters less than 0.1 AU.

 May 11, 2007:
    -- There will be no updates to asteroid and comet orbit solutions (or the
        small-body database) for the next 3 days due to maintenance activity 
        over the weekend. The Horizons server will still be up and running, but
        with the current dataset.
    -- Orbit solutions for newly discovered Saturnian satellites 2007S1, 
        2007S2, and 2007S3 are now available.

 Apr 19, 2007:
    -- Version 3.31b:
        Galactic System II longitude has been added to the output of observer 
        table quantity #33 (formerly galactic latitude only) and the number of
        output digits increased.

 Apr 16, 2007:
    -- Saturnian satellite solutions updated for 619-631, 636-648, 65035,
        65040-65041, 65045, 65048, 65050-65051, 65053. New numberings and
        names of 636-648 were added in accordance with IAUC 8826.

 Mar 30, 2007:
    -- Satellites Adrastea and Metis updated to JUP230 solution.

 Mar 29, 2007:
    -- Herschel reference trajectory updated.

 Mar 28, 2007:
    -- Neptunian satellites 809-813 have been updated to reflect recent IAU
        numbering and naming:

              809 = Halimede = 2002N1
              810 = Psamathe = 2003N1
              811 = Sao      = 2002N2
              812 = Laomedeia= 2002N3
              813 = Neso     = 2002N4

 Mar 23, 2007:
    -- Recent updates to Earth orbiting mystery objects NEOCP 6R10DB9 and 
        NEOCP 6Q0B44E. 6Q0B44E is thought to be man-made, 6R10DB9 is currently
        ambiguous, but leaning toward natural. 

 Jan 04, 2007:
    -- The Horizons system is expected to be unavailable Jan 6 14:00-23:30 UTC
        (Sat morning thru mid-afternoon, for those in the US) due to electrical
         maintenance work on the building housing the Horizons server.
        This also applies to Sentry, SkyMorph, and the ssd/neo.jpl.nasa.gov 
        web-sites.

 Jan 04, 2007:
    -- Jovian satellites 517-527 have been updated to solution JUP261

       Jovian satellites 539-548 have been updated to solution JUP262 and the
        new IAU approved names attached.

       Jovian satellites 549-563 (unoffical non-IAU numbers) have been
        renumbered using JPL provisional numbers 55049-55063 
        (see April 6, 2004 news item for description)

       It's best if satellites are selected using their designations to avoid
        confusion over changes in relative numbering for objects not yet 
        addressed by the IAU.  For example, the previous object numbered
        553 was "2003J13". The object now with provisional code 55053 is
        instead "2003J3".  

       The five-digit provisional codes are meant to avoid confusion in the 
        future, when the IAU assigns official codes, but it certainly can
        create confusion during transition.  Thus the recommendation to do 
        look-ups using designations.  If there are questions about which 
        Jovian satellite is which, we'll be glad to help sort it out.

 Nov 07, 2006:
    -- For the Nov 17 - Jan 02 interval, send problems or questions to 
        "webmaster@ssd.jpl.nasa.gov".  

        E-mail to my personal address will remain unanswered until then, being 
        on an expedition to climb Antarctica's Vinson Massif (highest mountain)
        and then ski on to the South Pole. However, count on our crack team 
        here to keep an eye on things and help out when needed. 

 Oct 25, 2006:
    -- The STEREO 3rd stage trajectory (to re-entry) is now available, as are 
        3-sigma injection trajectory variations.  Type "stereo" to see the list
        of 7 trajectories, or a unique ID or name fragment to pick a particular
        one to use. 

        For example, "A+3" for the STEREO-A +3-sigma injection variation. 
        Or "AHEAD" for the nominal trajectory of STEREO-A (same as specifying 
        "-234", etc.)

 Oct 20, 2006:
    -- MESSENGER trajectory update for Venus Flyby #1 (Oct 24) now available.

 Oct 19, 2006:
    -- Pre-launch trajectories for solar observatories STEREO-A and STEREO-B
        are now available. Nominal launch is Oct 26.

 Oct 18, 2006:
    -- Jovian satellites 506-513 have been updated to solution JUP256, based 
        on all measurements reported through August 2006.

 Sep 28, 2006:
    -- Saturnian satellite solutions have been updated to include Cassini
        spacecraft tracking data through June 2006:
         601-609, 612-614, 632 (and 699 itself), available over 1799-2200 
         time-span.  Also 610-11 & 615-617 over a shorter span (1980-2014).  

 Sep 15, 2006:
    -- Three new Saturnian satellites are now available:
          633,  Pallene     S/2004 S2 ("2004S2" in Horizons)
          634,  Polydeuces  S/2004 S5 ("2004S5" in Horizons)
          635,  Daphnis     S/2005 S1 ("2005S1" in Horizons)

 Sep 12, 2006:
    -- Pluto: Horizons has been altered such that if numbered object 134340 
        (the Minor Planet Center assignment for Pluto) is requested, the result
        will be based on the current n-body solar system planetary solution, 
        presently DE413/DE405. This will provide more accurate trajectory data 
        than an independent solution and perturbed asteroid integration.

 Aug 11, 2006:
    -- Version 3.30a: fixes an error introduced in the 2005-Dec-10 update. 
        Leap-seconds began inadvertently being applied 12-hours too early. 

        For example, the most recent leap-second was to be implemented on 
        2006-Jan-01 00:00. After the program update, it was instead applied 
        2005-Dec-31 12:00. Thus, UTC ephemerides for times inside that 12-hour 
        interval were 1-second early. Once 2006-Jan-01.0 arrived, UTC was 
        again as intended. 

        Summarizing: 
         only UTC observer ephemerides were affected; 
         only ephemerides made between 2005-Dec-10 and now were affected; 
         only output during the 12-hour interval before leap-second changes
           for such products was impacted;
         time-tags (only) were off +1-second only.

        Observationally, this should be visible only in some high-precision 
        spacecraft or radar applications for that 12-hour interval and is
        comparable to the positional uncertainty of most objects.

        Thanks to Elisabeth Adams at MIT for noticing the difference between
        word and deed and bringing it to my attention!

 Jul 14, 2006:
    -- Nine newly discovered Saturnian satellites are now available:
        2004S19, 2006S01-S08. The number assignments are provisional JPL
        values 65047 - 65055, as per convention described in news item 
        of Apr 06, 2004.

 Jul 02, 2006:
    -- The orbit solution of 2004 XP14 was just updated for tonight's 1.1 lunar
        distance close-approach. Solution #35 includes recent measurements that
        haven't had a chance to be released in the MPC DOU.

 Jul 01, 2006:
    -- Version 3.30
        * Horizons can now compute ephemerides for surface points on extended,
           rotating target bodies (Moon, Sun, planets, natural satellites).
         
          When selecting such a target (those with an IAU rotational model),
          use this form (units are degrees and km):

              {g: E.Long, latitude, h@}BODY  [geodetic/planetographic coords.]
              {c: E.Long,     DXY, DZ@}BODY  [cylindrical coordinates]

          For example,

                g: 348.8, -43.3, 0 @ 301

          ... specifies the crater Tycho on the Moon (body 301), at geodetic 
          (planetographic) coordinates 348.8 degrees east longitude, -43.3 
          degrees latitude (south), and zero km altitude with respect to the
          IAU reference triaxial ellipsoid.

          For cylindrical coordinates, DXY is distance from the spin axis in
          the body equator plane in km, DZ is distance above (+) or below (-) 
          that plane,  also in km.
        * When a surface target is specified, two new markers are output in
           "observer tables".  They indicate if the point on the target
           surface is lit (by the Sun) and if it is on the near or far-side 
           of the target body relative to the observer.
        * Altered descriptions are printed at the end of the tables as
           necessary to describe the output.
 
 Jun 16, 2006:
    -- Spacecraft trajectories recently updated: 
             New Horizons, Herschel, MESSENGER
       Limited Pioneer 6 and Pioneer 8 trajectory data (all we have) is
       now available.

 Apr 28, 2006:
    -- Saturnian system objects 601-609, 612-614, 632, 699 have been updated 
        based on a new solution which includes all Cassini tracking data 
        through 2006-Apr-24.

 Apr 27, 2006:
    -- Phobos and Deimos trajectories have been updated to use the new MAR063 
        solution (Jacobson, JPL).  First update since 1996. New solution fits 
        newly reported optical data from USNO and Table Mountain, as well as 
        spacecraft tracking data from MGS and MEX orbiters.

 Apr 25, 2006:
    -- Telnet users: a login banner was added at the request of JPL security. 
        Check any automation scripts that might parse the I/O stream and get 
        thrown by the new pattern.

 Apr 19, 2006:
    -- A preliminary trajectory for the Herschel Space Observatory (ESA) is 
        now available, ID #= -486. Mostly for testing. Launch date not firm
        at this point.
    -- The logic of the "CAP;" directive has been slightly altered. In the 
        past, if there was no comet apparition solution with an epoch earlier
        than the user request (or the current date, if no epoch was specified
        by the user), no match would have been returned.

        NOW: Horizons will return the next future apparition. For example, 
        say the only apparition available for 73P-N is in 2006. If you request 

                             DES= 73P-N; CAP < 2000 

        ... the only available apparition solution (2006) will be returned
        as a match. Previously, a "no match" message would have been returned.
        Of course, a search of "73P-N" would also match and mean less typing. 
        But the change is primarily to support the web interface.

    -- To accomodate the ongoing break-up of comet 73P/Schwassmann-Wachman 3, 
        fragment codes have been extended to two characters. That is, there 
        is now a "73P-AA", "73P-AB", etc. There are currently 37 orbits
        related to 73P available, 33 of them for the current apparition.
    -- For historical reasons, designations really are case sensitive. That 
        is, there is a comet designated "73P-G", but there is no comet "73p-g"
        or "73P-g".
    -- Also, one need only specify a number OR name. Giving both is unnecessary
        (being redundant {see what I did there}) and not supported. Thus,
        "DES= 73P-G;" is sufficient, while a search on "73P-G/Schwassmann-
        Wachmann 3-G" won't find anything.  "1;" will match Ceres, "Ceres;" 
        will match Ceres, but "1 Ceres;" won't match anything. 

 Apr 06, 2006:
    -- Uranian satellites 725-727 have been updated.
    -- Cassini spacecraft trajectory was updated.
    -- Hubble Space Telescope was updated with predicts to May 4.
    -- Version 3.20d:
        A new "NOFRAG" directive was implemented such that comet searches can 
        now exclude fragments.  For example, from the telnet prompt line: 
  
       "DES= 73P;"              (lists all 73P/Schwassmann-Wachmann 3 records)
       "DES= 73P; NOFRAG;"      (lists all 73P pre-fragmentation solutions)
       "DES= 73P; NOFRAG; CAP;" (selects last 73P apparition pre-fragmentation 
                                 solution)
       "COM; NOFRAG;"           (Shows all comets, excluding fragments)
       "COM; CAP; NOFRAG;"      (Shows last apparition of all comets, 
                                 excluding fragments)
 Mar 01, 2006:
    -- A new web interface to Horizons is available:

            http://horizons.jpl.nasa.gov/?horizons.html

       The interface accesses more system capabilities, including those
       previously available only via direct telnet connections or e-mail 
       command-files. For example:

          * obtain Cartesian vector and orbital element tables
          * observer/center is no longer restricted to Earth
          * access to all table settings
          * discrete time output (up to 10 values)
          * settings are saved between sessions for a given IP address
          * improved user-interface

       Horizons Things NOT available from the new site (but by telnet or
       e-mail):

            user-input objects
            SPK binary-file generation
            customized close-approach tables
            small-body parameter matching ... but see also: 

                  http://ssd.jpl.nasa.gov/sbdb_query.cgi

         ... for a new search capability.

    -- The web site in general has been redone. For a summary, see:

                      http://ssd.jpl.nasa.gov/?new

       Many thanks to our webmaster Alan Chamberlin for this enhanced web 
       access.

 Feb 22, 2006:
    -- New orbit solutions for 38 Saturnian satellites (and Saturn planet
        center) are now available: 601-609,612-614,619-632,699, 65035-65046.
        "632" (Methone, SXXXII, S/2004 S1) was newly added.
    -- Version 3.20b: photometric magnitude laws were updated for Pluto and
        Mercury.  Changes are less than 0.1 mag, so within the existing
        uncertainty level.

 Feb 01, 2006:
    -- Ulysses trajectory updated; now extends to 2015.

 Jan 31, 2006:
    -- Stardust bus trajectory updated to 2010 based on post-encounter tracking
        & navigation solution. No further updates unless spacecraft retasked.
    -- Saturnian satellites 610-611,615-617 have been updated to new solution
        SAT238.

 Jan 24, 2006:
    -- This system now uses a mission-length reference trajectory for the
        New Horizons spacecraft, provided by APL. Span is thus 2006-Jan-19
        to 2015-Jul-26.

 Jan 21, 2006:
    -- The New Horizons Spacecraft (mission to Pluto) post-launch trajectory
        is available. Access using "-98" ID number or "New_" abbreviation
        or full "New_Horizons" (or pull-down menu via the web). The underscore
        is required for now to avoid conflict with this system's news function.

 Jan 11, 2006:
    -- Stardust spacecraft bus (-29) and SRC (-29900) trajectories have been 
        updated to reflect post TCM-18 (maneuver) tracking data. Trajectories
        provided by Stardust navigation.
    -- Three new Uranian satellites are available: Perdita, Mab, and Cupid.
    -- Version 3.20a:
         Osculating element output for spacecraft wrt to planetary bodies
         has been enabled.

 Jan 03, 2006:
    -- Trajectories for Stardust spacecraft bus and Sample Return Capsule have
        been updated (051229 navigation solution/prediction).
    -- Solutions for Uranian satellites 716-724 have been updated to URA072.
        722-724 now reflect the recently announced official IAU names.

 Dec 10, 2005:
    -- Version 3.20:
         A source of periodic (non-cumulative) meter-level noise in light-time
         corrected integrations (for asteroids/comets only) was identified and 
         removed.  Light-time corrected state consistency is now comparable to 
         integrations for SPK and geometric states (less than 1.0 mm).

 Dec 07, 2005:
    -- Deep Impact spacecraft trajectory has been extended to the potential
        encounter with 85P/Boethin, including Earth gravity assist.
    -- Spitzer Space Telescope trajectory has been updated to latest solution.

 Nov 15, 2005:
    -- Venus Express spacecraft reference trajectory (ESA) is now available.
    -- System activity last month:
        Connections:               Products:
          Telnet          7895        Telnet         22457
          WWW            23853        WWW            37534
          E-mail          9372        E-mail         25220
                                      SPK obj/fil      758/758
          --------------------        --------------------
          Total(month)   41120        Total(month)   85969
         >TOTAL(Oct96) 3098162       >TOTAL(Oct96) 4483318

 Nov 04, 2005:
    -- Version 3.17c:
        * Decimal input dates are now allowed. For example:

             2005-Jan-12.66449
             2005 01 12.66449

          Previously, HH:MM:SS.fff format, or Julian Day Numbers, were the 
          only way of expressing fractional days.

        * User-input start-time precision is now used to determine output
           time precision. For example, if start-time is 2004-Nov-04 12:15:35, 
           output will begin at that time and print time-tags with 1-second 
           precision.

          Previously, user-input start time was rounded to the nearest minute, 
          and the ephemeris stepped accordingly thereafter.

 Oct 18, 2005:
    -- Natural satellites 601-609, 611-614, and planet center 699, were updated
        to new solution SAT225.  It's based on Earth, Voyager, HST and Cassini 
        optical data, as well as Pioneer, Voyager and Cassini radiometric 
        tracking data reported through Dione encounter on 11 October 2005. 

 Oct 13, 2005:
    -- The system has been updated with the new Stardust spacecraft trajectory
        for both the Sample Return Capsule (SRC) and main bus at the time of
        the 2006-Jan-15 Earth return. Trajectories will be updated as the
        return date approaches, but currently ...

        SRC separation from s/c bus: 2006-JAN-15 05:57:05.519 UTC
        SRC atmospheric entry      : 2006-JAN-15 09:56:38.576 UTC

       More information is in the data sheets for each object.

    -- The web interface was altered to return body information data sheets
        by default. The previous default was "no summary", but the data
        often contains information on special cases and other notes web
        users were missing by not checking the box.
    -- The MRO trajectory was extended through Mars Orbit Insertion on 
        2006-Mar-10.

 Oct 11, 2005:
    -- With today's Earth timing and orientation model update file, Horizons 
        UTC times will reflect the positive leap-second announced by the IERS
        for 2005-Dec-31. The sequence of UTC labels will effectively be:		
		
                           2005-Dec-31 23h 59m 59s
                           2005-Dec-31 23h 59m 60s
                           2006-Jan-01  0h  0m  0s

       The difference between UTC and International Atomic Time (TAI):

        From: 1999-Jan-01, 0h UTC, to 2006-Jan-1  0h UTC: TAI-UTC= +32s
        From: 2006-Jan-01, 0h UTC, until further notice : TAI-UTC= +33s

 Sep 29, 2005:
    -- A new solution for 9P/Tempel 1, based on ~4000 opnav images is 
        available. Accuracy is best near encounter time. Improved trajectories 
        for the flyby and impact spacecraft are also available, but final 
        reconstructions will be posted when released by the navigation team.

 Sep 27, 2005:
    -- Version 3.17:
        A defect in Earth-site ASCII-table topocentric velocities ("deldot", 
        VX,VY,VZ, etc.) only, introduced in the 2003-May-20 update (version 
        3.10), was corrected. Thanks to James Miller (Cambridge, UK) for 
        recognizing and pointing it out. 
        
 Aug 23, 2005:
    -- Version 3.16b:
        Horizons was altered to use an absolute magnitude of H= 99 for those
        asteroids with no reported H value.  Previously, objects with an 
        unknown absolute magnitude were assigned "H = 0" as the default.

 Aug 15, 2005:
    -- Natural satellites 601-609, 611-614, and planet center 699, were updated
        to new solution SAT215 (Jacobson, DPS 2005).  It's based on Earth, 
        Voyager, HST and Cassini optical data, as well as Pioneer, Voyager and 
        Cassini radiometric tracking data reported through July 22, 2005.
 
 Aug 14, 2005:
    -- MRO Centaur booster trajectory is available over Aug 12-20, 2005. 
        Optical astrometry would be helpful in estimating Mars impact
        probability. Assigned body code "-7400" is unofficial.

 Aug 09, 2005:
    -- MRO launch delayed 1 day. The trajectory was updated in Horizons for
        the new Aug 11 opportunity.

    -- PRIVACY NOTE: 
        For user-input objects (where orbital elements are entered manually), 
        no record is kept of what is entered. Once you disconnect, the 
        definition ceases to exist and cannot be reconstructed by anyone, 
        including system operations. If you FTP results to yourself however, 
        the file will remain on the server, as usual, for 30 minutes before 
        being automatically deleted.

 Jul 12, 2005:
    -- Version 3.16:
        Ancient comets have been added to the small-body database.
    -- Mars Reconnaissance Orbiter (MRO) spacecraft is now available over a 
        limited time span (separation to separation + 14 hours).
        
 May 11, 2005:
    --  Comet 9P/Tempel 1 centered output is now available in Horizons.
         (telnet and e-mail interfaces). When asked for a coordinate center, 
         respond "@9P" or "@Tempel 1", or "@1000093" (the SPK ID number).  

        One can see the recognized match  codes/names for all "major bodies"
         (those that have precomputed trajectory files)  by typing "mb" at the
         main prompt (mb means "major bodies").

        For example, if you want calculations relating to the Deep Impact
         spacecraft impactor approach to 9P/Tempel 1, you could select target 
         -70 with coordinate center @9P.  For the flyby vehicle, request -140, 
         with coordinate center @9P, and so on.
 
 Apr 28, 2005:
    -- Comet search flexibility was improved. It's no longer necessary to know
        the comet's prefix -- it can change anyway. For example, if you search 
        for "1983 V1", Horizons will still match 'P/1983 V1'. If you request
        "C/1983 V1", it will still find "P/1983 V1". And so on. A search on
        "2003 S4" will now match both fragments "C/2003 S4-A" and "C/2003 S4-B"
        (you will have to select one or the other to proceed further).

 Mar 24, 2005:
    -- The new PLU013 solution for Charon (901) and Pluto planet-center (999) 
        is available. The solution is a fit to all available observations and
        has these barycentric 1-sigma (68.3% confidence) uncertainties:

                    EPHEMERIS ACCURACY (PLU013/DE413 solution)
                         Radial  Downtrack Normal   Period
                           km       km       km       sec
                         ------  --------- ------  -------
                         100.00   300.00   20.000    1.000

        Chebyshev interpolation error: 5 meters (the accuracy to which 
        the PLU013 solution will be reproduced by Horizons).

 Mar 07, 2005:
    -- On 2005-Jul-11, Pluto's satellite, Charon, is expected to occult the
        15th magnitude star UCAC2 26257135.  Correct positional knowledge of 
        the star and Charon are critical to the geometry of the event since 
        Charon's 1200 km diameter amounts to only 0.055" in the plane-of-sky. 

        To support this, Horizons has been updated with a new solution for the
        Pluto Barycenter (9), DE413. It includes measurements taken over the 
        past year. A realistic plane-of-sky uncertainty for the position of 
        Pluto in DE413 is +/- 0.02". 

        The Charon satellite and Pluto barycentric offset vector solutions 
        (901 & 999) have also been updated to solution PLU009 and are expected 
        to be updated again.

    -- Horizons has been updated to use the best planetary ephemeris for a 
        given object and time and indicate which of those solutions was used 
        on the output tables.  Currently, this is:

             Bodies         Time interval                   Solution
        ------------------  ------------------------------  --------
            ALL             3001BC-Jan-29 -> 1599-Dec-10      DE406
            ALL               1599-Dec-10 -> 1899-Dec-05      DE405
            ALL but 9         1899-Dec-05 -> 2050-Mar-07      DE405
            9                 1899-Dec-05 -> 2050-Mar-07      DE413
            ALL               2050-Mar-07 -> 2201-Feb-20      DE405
            ALL               2201-Feb-20 -> 3000-May-06      DE406

        Notes:
         1) "ALL" = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 199, 299, 301, 399, 499
         2) 199 is the same as 1--|
            299 is the same as 2  | (No barycenter offset vector)
            499 is the same as 4--|
         3) DE405 is, and always has been, used for integrating asteroid & 
             comet targets over 1599-2200.
         4) DE406 is the same planetary solution as DE405, but is extended in
             time and represented more coarsely such that there is a periodic
             error of max. amplitude ~25 meters in the reconstructed state
             vectors (to save space).
         5) By contrast, DE413 is a different solution, reflecting more 
             recent data on Pluto. It should be preferred for that object 
             over the time-span defined for the DE413 solution.
         6) Previously, to avoid switching ephemerides if a planetary request
             crossed a time boundary, DE406 was just used for all planetary 
             requests. This behavior has changed. Now, Horizons will switch 
             between the best available ephemeris, using DE405 or DE413 if
             it can.  This should provide a few more meters of accuracy for 
             most major planets (and about 1000 km for Pluto in the new 
             DE413 solution).

 Mar 02, 2005:
    -- The Hubble Space Telescope historical trajectory was added to Horizons.
        This will allow calculation of HST-centered coordinates over intervals 
        from launch to now (e-mail & telnet only). The trajectory will be 
        updated on request, or every couple months otherwise.
        
 Mar 01, 2005:
    -- The system was updated with the latest Rosetta trajectory in preparation
        for the 2005-Mar-4 22:09 UTC Earth flyby.

 Feb 25, 2005:
    -- Version 3.15: 
        CT-UT delta calculations were altered to use the cubic-spline 
        fit-to-eclipse data of Stephenson, over the 501BC-1621 interval. 

        The parabolic theory used prior to 501 BC was also altered to correct 
        for lunar tidal acceleration (n-dot) of the DE405/406 solution being 
        -25.733 "/cty^2 (instead of the -26 "/cty^2 used by Morrison in his
        reduction).

 Feb 10, 2005:
    -- Apparent magnitude calculations for asteroids are now available only 
        when the solar phase angle is less than 120 degrees. For greater 
        values, the "n.a." ("not available") marker will be output, since the 
        errors can be large. Even for phase angles > 90 degrees, the apparent 
        magnitudes can be off by a magnitude or more, since the calculations 
        are derived from Earth-based measurements at limited observing 
        geometries (i.e. Earth's orbit at 1 AU).

        For planets and natural satellites seen from spacecraft, apparent 
        magnitudes are now available, but only for the range of solar phase 
        angles comparable to that seen from Earth (on which the magnitude
        models are data-based).

 Feb 02, 2005:
    -- The Rosetta trajectory has been updated in preparation for the March 4,
        2005 Earth flyby.

 Jan 06, 2005:
    -- The planned trajectory for Deep Impact is now available, launching
        on Jan 12 (for those attempting to observe the spacecraft).
    -- The Huygens predicted Titan atmospheric descent trajectory is now 
        available.

 Nov 29, 2004:
    -- Jovian satellites 517-538, 540-561, and 55062-55063 have been updated
        to new solutions based on new data. Satellite "S/2000 J11" was removed, 
        being "lost" since the initial discovery and possibly spurious.

 Sep 02, 2004:
    -- The post OTM-10 Genesis trajectory solution is now available. The next
        maneuver prior to entry Sep 8 will be on Sep 6, for those of you
        planning to observe the spacecraft. The planned bus-divert trajectory
        is also available.

 Aug 16, 2004:
    -- Horizons will probably be unavailable Saturday Aug 21 00:00 - 23:30 UTC 
        due to routine maintenance on building power grid. These things often 
        get called off at the last minute, but you might want to allow for it.

 Jul 12, 2004:
    -- ~65,000+ new asteroids are available (253,505 asteroids in total as of 
        now). The Horizons asteroid & comet database was switched over to be 
        the export product of a new relational database. Primary consequences 
        to users are ...

        * Additional asteroids are available, including single opposition 
           objects having data arcs less than 30 days (formerly excluded).
           Many of these objects have very poorly determined orbits. Many were
           fit using two-body assumptions, as indicated in the object summary 
           page. Appropriate warnings will be issued with output ephemerides 
           for such objects.
        * Object record numbers will change more easily for comets and
           unnumbered asteroids. You should instead be requesting objects by 
           name, designation or JPL/NAIF-ID, which are permanent identifiers.
        * You may notice changes in some comment lines.
 
 Jul 08, 2004:
    -- The Messenger spacecraft trajectory is now available through Horizons.

 May 14, 2004:
    -- The Hayabusa trajectory has been updated for the 2004-May-19 06:21:40
        (UTC) ~10104 km close-approach to the Earth's center (3725.8 km from
        surface).
    -- The Cassini trajectory was updated today to reflect final planning
        for Saturn orbit insertion.

 May 10, 2004:
    -- The Horizons server has been upgraded. The new machine is ~4-6 times
        faster.

 Apr 29, 2004:
    -- The Genesis spacecraft trajectory has been updated here for those 
        intending to observe near the May 1 Earth close-approach.

 Apr 28, 2004:
    -- Curious about comet solution references? Here's how to decode them:

        General form: XYYA/NN
                      ^^^^ ^^
                     class/Solution # within class

        Meaning ...  X= Century code (J=1900's, K=2000's) of last apparition
                    YY= Apparition year (within century X) of last data in fit
                     A= Number of apparitions of data in fit
                    NN= Solution number within class

       Example: K035/18
         Means solution #18 of the class of solutions containing 5 apparitions
         of data ending with the 2003 apparition.

 Apr 13, 2004:
    -- Version 3.13c:
        Leading/trailing marker flag (part of quantity #23) was fixed. Objects
        trailing the Sun by 6-12 hours of RA, as seen from a non-retrograde
        observer, were being marked "/L". 

 Apr 06, 2004:
    -- The Rosetta trajectory was added to Horizons.
       The Huygens probe Titan atmospheric descent trajectory was added.
    -- Coordinates for Mars rovers Spirit and Opportunity have been added
        to the Martian site list. Select as observing centers with codes
        "Spirit@499" or "Opportunity@499".
    -- Newly recognized Jovian satellites 2003J22 and 2003J23 are now
        available.
    -- Version 3.13:
        * Support was added for 5-digit natural satellite numbers. The new 
           system allows for the possibility of bodies having more than 98 
           natural satellites while maintaining identity across provisional 
           numberings. It works like this:

          Satellite codes (3 types):

          A) 3-digit format if numbered by IAU and LESS than 99 satellites are
             known for given system:
              xxx
               xxx = 100*system-code (1-9) plus IAU number

          B) 5-digit format if numbered by IAU and MORE than 98 satellites are
             known for a given system:
              p0xxx
               p   = system-code (1-9)
               0   = flag denoting IAU numbered
               xxx = IAU number (1-999)
        
          C) 5-digit format if unnumbered (JPL provisional assignment):
              p5xxx
               p   = system-code (1-9)
               5   = flag denoting provisional (non-IAU) numbered object
               xxx = JPL assigned code (1-999).

          For example, a new Jovian satellite might get a provisional JPL 
          integer assignment like 55067.  Months or years later, it may then
          be officially numbered by the IAU as, say, JLXXIII (Jupiter 73).
          While "55067" will remain as an alias for look-up purposes only,
          Horizons will also adopt "573" as the primary numeric reference 
          (being one of the first 98 natural satellites).
 
          If a JPL provisional assignment of say 55116 is made, and the IAU
          later officially assigns it as JCXIII (Jupiter 113), it will be
          renumbered in Horizons as "50113". It could then be accessed by
          name, designation, provisional "55116" number, or official "50113"
          number.

          It is best to request objects by name or designation and avoid 
          such numbering issues.

        * Light-time buffers on available time-spans were relaxed for 
           spacecraft trajectories to permit ephemeris generation near 
           terminal events (landings, etc.). The trade-off is ephemerides of 
           the spacecraft seen from distant observers (on another planet) can
           halt with an error message due to light-time iterations running
           off the end of the available trajectory model. But benefits seem
           to outweigh that problem. 

 Feb 17, 2004:
    -- The rotation model for Phoebe (609) has been updated to match IAUC 8279 
        (1/30/2004). The previous IAU model was based on Voyager fly-by data.
    -- The Genesis spacecraft reference trajectory has been updated (Sep 2003
         version).

 Jan 09, 2004:
    -- Version 3.12:
        * Comet non-grav parameters A3 and DT (normal acceleration component
           and lag/delay time) are now supported in the Horizons database and
           force propagation. Solutions with the new A3 & DT parameters do not
           yet support covariance mapping (uncertainties).
        * Some supporting databases were reorganized, including improved
           "IAU number" records and aliases for natural satellites (see "MB"
           command).

 Oct 08, 2003:
    -- Newly discovered & recovered Uranian satellite S/2001U3 is now 
        available via Horizons. Select with ID# (723) or designation (2001U3). 

 Oct 02, 2003:
    -- New Jovian satellite names and numbers adopted by the IAU are now
        reflected in Horizons:

          ID # Temporary Desig.   Formal Designation    Name
          ---- ----------------   ------------------    ------------
          528  S/2001J1           Jupiter XXVIII        Autonoe
          529  S/2001J2           Jupiter XXIX          Thyone
          530  S/2001J3           Jupiter XXX           Hermippe
          531  S/2001J11          Jupiter XXXI          Aitne
          532  S/2001J4           Jupiter XXXII         Eurydome
          533  S/2001J7           Jupiter XXXIII        Euanthe
          534  S/2001J10          Jupiter XXXIV         Euporie
          535  S/2001J9           Jupiter XXXV          Orthosie
          536  S/2001J5           Jupiter XXXVI         Sponde
          537  S/2001J8           Jupiter XXXVII        Kale
          538  S/2001J6           Jupiter XXXVIII       Pasithee
 
 Oct 01, 2003:
    -- Newly discovered Uranian satellite S/2001U2 is now available. Access 
        with designation ("2001U2") or temporary number, "722", at main prompt.

 Sep 10, 2003:
    -- The rotational direction of satellite Triton (801) about its spin axis,
        affecting planetographic longitude, was corrected to retrograde. 

 Aug 15, 2003:
    -- A sequential queuing system has been implemented for Horizons e-mail 
        batch jobs. E-mail jobs are now processed one at a time by Horizons in 
        the order received. Previously, multiple jobs were executed in parallel
        which could degrade overall system response when dozens or hundreds of
        requests arrived at once.
    -- The "LIST;" option default has been changed from "NO" to "YES" so that
        parameter searches will automatically display the actual values of the
        matching keywords (telnet/e-mail only). Typing LIST at the main prompt
        will toggle the option as always.
    -- Horizons asteroid/comet orbit solutions are automatically updated within
        1-2 hours of observational measurements being made publicly available.

 Aug 04, 2003:
    -- Numbers have been changed and names assigned to conform to the newly
        adopted IAU Saturnian satellite nomenclature:

             Newly Named Satellites of Saturn
        ID#  Temporary Designation   Formal Designation    Name
        ---  ---------------------   ------------------    ---------
        619  S/2000 S 1              Saturn XIX            Ymir
        620  S/2000 S 2              Saturn XX             Paaliaq
        621  S/2000 S 4              Saturn XXI            Tarvos
        622  S/2000 S 6              Saturn XXII           Ijiraq
        623  S/2000 S 12             Saturn XXIII          Suttung
        624  S/2000 S 5              Saturn XXIV           Kiviuq
        625  S/2000 S 9              Saturn XXV            Mundilfari
        626  S/2000 S 11             Saturn XXVI           Albiorix
        627  S/2000 S 8              Saturn XXVII          Skadi
        628  S/2000 S 10             Saturn XXVIII         Erriapo
        629  S/2000 S 3              Saturn XXIX           Siarnaq
        630  S/2000 S 7              Saturn XXX            Thrym

 Aug 01, 2003:
    -- The Stardust spacecraft trajectory has been updated to include the
        planned January 2004 cometary encounter.
    -- To support the Stardust encounter with comet Wild 2, two types of 
        comet trajectories are being made available on Horizons:

          1) Standard out-gassing model (solved-for A1, A2 only)
               Time span: A.D. 1600 - 2200 (dynamic propagation)
               Access using keywords: NAME= WILD 2, DES= 81P, etc.

          2) Extended out-gassing model solution (solved-for A1, A2, A3, DT)
               Time span: A.D. 2002 - 2007 (static interpolation)
               Access WITHOUT keywords: "Wild 2" or "81P" at main prompt.

       #1 is fine for ground-based observers. #2 is being used by the
       Stardust project for the encounter. 

       If you wish to generate a spacecraft ephemeris as seen from Wild 2, 
       select Stardust as the target and specify a coordinate center "@Wild 2".

       If you wish to generate a Wild 2 ephemeris as seen from Stardust,
       select "Wild 2" as target (#2 trajectory above), and specify a 
       coordinate center "@stardust" 

       If you are interested in Wild 2 independent of Stardust, and need an 
       ephemeris outside of the 2002 to 2007 interval, select it as a
       target with "NAME= Wild 2".
 
 Jul 15, 2003:
    -- Planet & satellite rotational models (and radii) were updated to conform
        to the IAU2000 models published in ... 

          `Report of the IAU/IAG Working Group on Cartographic Coordinates and
           Rotational Elements of the Planets and Satellites: 2000', Celestial
           Mechanics and Dynamical Astronomy 82: 83-110, 2002.

       Particularly noteworthy is a -0.271 degree change in the prime meridian 
       angle (W) of Mars, compared to the previous IAU1997 model.
    -- The Opportunity (Mars Exploration Rover) spacecraft trajectory is now
        available from Horizons.

 Jun 20, 2003:
    -- Spirit (Mars Exploration Rover), Mars Express and updated Nozomi
        spacecraft trajectories are now available from Horizons.

 Jun 16, 2003:
    -- To better accomodate the new SMASS-II asteroid spectral types, searches
        using the STYP keyword are now case-sensitive. 

       SMASS-II contains 26 classes, 12 of which follow previous convention:
           A, B, C, D, K, O, Q, R, S, T, V, and X

       There is a new L-class. Objects with intermediate spectral 
       characteristics have multi-letter designations with upper/lower case:

           Cb, Cg, Cgh, Ch, Ld, Sa, Sk, Sl, Sq, Sr, Xc, Xe, Xk

       Thus, if you search with ...
          STYP= S , you will match on "S, Sa, Sk, Sl, Sq, Sr"
          STYP= S*, you will match on "S, Sa, Sk, Sl, Sq, Sr"
          STYP= Sa, you will match on Sa only
          STYP= s , you will match on NOTHING (case sensitive).
          STYP= SA, you will match on NOTHING (case sensitive).
          STYP= g,  you will match on Cg and Cgh
          STYP= *,  you will match on all objects with a known spectral type.
          STYP<>*,  you will match on all objects without a spectral type.

       It is recommended one have the LIST option active so the matching value
       is output. Type LIST at the main prompt, or add to search parameters
       (i.e. STYP= Sa; LIST;)

 May 30, 2003:
    -- Newly discovered Jovian satellite 561 is now available.

 May 20, 2003:
    -- Version 3.10:
        * A high precision Earth rotation model has been implemented for Earth 
           topocentric observer & vector tables as well as output using the UTC 
           time scale.
        * Earth Orientation Parameter (EOP) files based on GPS timing data 
           (updated twice a week) are now used by Horizons to adjust for 
           measured polar motion, CT - UTC, CT - UT1, and nutation corrections. 
        * The improved Earth model allows transformation of station body-fixed 
           coordinates to the inertial frame good to at least 10 meters 
           (previously, the error was potentially as great as 500m). However, 
           many OPTICAL site body-fixed latitude and longitude coordinates are 
           not known to that level to start with.

 May 08, 2003:
    -- The lunar magnitude formulation was changed to incorporate distances 
        from Sun and Earth [LOG10(r*R) term]. Previously, mean values for both 
        were used. 

 Apr 12, 2003:
    -- Newly discovered Jovian satellite 559 (S/2003J19) is available.
    -- Newly discovered Saturnian satellite 631 (S/2003S1) is available.
    -- Galileo & Cassini trajectories have been updated (INTEGRAL and 
        Chandra are updated fairly routinely).

 Apr 02, 2003:
    -- Version 3.03:
        * Look-up speed has been increased by a factor of ~10 for 
           asteroid and comet name & designation searches.
    -- Newly discovered Jovian satellites 553-558 are now available.

 Mar 20, 2003:
    -- Version 3.02:
        * Small change affecting observer tables disables computation of
           light-deflection due to a barycenter when the observing site is
           interior to a planet. Gravity deflection is now computed due to 
           planetary center (when observer is topocentric or not on the 
           system's primary planetary body) and the Sun.
        * RMSH is no longer displayed for asteroid data sheets.

 Mar 12, 2003:
    -- The Charon ephemeris has been updated to reproduce the satellite's orbit 
        with 0.7 meter maximum error relative to orbit solution. Previously, 
        the ephemeris could deviate up to 280 m from reproduction of the actual
        solution. Uncertainties of the orbit solution are much larger than 
        this, so the improved accuracy is not meaningful, but the tighter 
        Chebyshevs will aid production of consistent Pluto-centered osculating 
        elements for the near-circular orbit. 

 Mar 11, 2003:
    -- Newly discovered Jovian satellites numbered 549-552 are now available 
        in Horizons.

 Mar 06, 2003:
    -- Newly discovered Jovian satellites numbered 541-548 are now available
        in Horizons.

 Feb 26, 2003:
    -- Pluto and Charon GM's were updated to be consistent with the orbit
        solution, improving osculating element tables for that system.

 Feb 05, 2003:
    -- Orbit solutions have been updated to SAT132 for objects 601-608, 699
        (Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Hyperion, Iapetus
         and Saturn planet center).
    -- Data sheet mean radius, GM, mass and density for Saturnian satellites
        601-608 and planet (699) have been updated based on new solutions
        (JPL IOM 312.F-03-001) which incorporate all Earth and spacecraft 
        tracking data.

 Jan 07, 2003:
    -- Pioneer 10 and Pioneer 11 trajectories have been installed in Horizons.
        Access by name or spacecraft code (-23 and -24 respectively).

 Nov 13, 2002:
    -- Version 3.01:
        * Fixed small-body integration to prevent rare halt condition.
        * When specifying custom objects, one may define an 'area-to-mass'
           ratio (AMRAT= 'X', where X is m^2/kg), activating a solar pressure
           model. A spherical body is assumed. The SRP model assumes total 
           light absorption, so scale AMRAT by multipliers between 1 and 2 to 
           account for reflectivity. For example, if the albedo is 15%, multiply
           the actual area-to-mass ratio by 1.15 and supply the resulting value
           as AMRAT. Once activated, the model is turned off by setting AMRAT=0.

    -- Comets were relocated in the database to RECORD numbers > 400000,
        since unnumbered asteroids exceeded 100000 in count. Summary:

                                    Formerly          Now
                                 -------------   -------------
           Numbered asteroids         1-100000        1-100000 
           Unnumbered asteroids  100001-200000   100001-400000
           Comets                200000-300000   400001-500000

        This is unrelated to SPICE or NAIF ID's numbers, which are unchanged. 
        If you don't know what any of this means, it doesn't matter.

 Nov 07, 2002:
    -- Jovian satellites 529-539 have had their orbits updated.
    -- Horizons usage summary 2002-09-15 to 2002-10-15
        Connections:               Products:
          Telnet          2962        Telnet         14779
          WWW            16060        WWW            16908
          E-mail         50122        E-mail        102461
                                      SPK obj/fil       65/22
          --------------------        --------------------
          Total(month)   69144        Total(month)  134213
         >TOTAL(Oct96)  721152       >TOTAL(Oct96) 1174144

 Nov 04, 2002:
    -- Jovian satellites 517-527 were updated to use the new IAU names and
        numberings, as per IAUC 7998.

 Oct 29, 2002:
    -- The ESA INTEGRAL spacecraft trajectory has been added to Horizons.
        Access by name ('INTEGRAL') or numeric ID: -198.

 Oct 01, 2002:
    -- Newly recognized Uranian satellite S/2001 U 1 (IAUC 7980) has been
        installed in Horizons as object "721" and "2001U1".

 Sep 27, 2002:
    -- A bug that caused some e-mail batch jobs containing user-input errors 
        to halt without returning an explanatory error message (resulting in a
        non-response) has been fixed. One should now always receive a response 
        to an e-mailed job.
    -- The object J002E3, possibly an Apollo 12 3rd stage temporarily
        captured into Earth orbit, may be requested under the name J002E3
        or by it's "temporary" numeric ID, -998.
    -- The three CONTOUR spacecraft fragment trajectories (CONTOUR-A, 
        CONTOUR-B, and CONTOUR-C are available by name or numeric ID
        (-204, -205, -206). CONTOUR-C has two possible trajectory variations
        on-line: -206 (long arc) and -207 (short-arc). None of the objects
        was observed beyond Aug 21.
 
 Aug 13, 2002:
    -- A character filter was installed to screen user input. This aids those 
        users whose connections send non-printing garble to standard input.

 Aug 12, 2002:
    -- The 1,000,000th product was generated by Horizons today at 11:22:33 a.m.

 Jul 11, 2002:
    -- A search filter has been added to Horizons that guarantees only
       one apparition will be returned for each comet. It is called "CAP;"
       and can be used three ways:

           CAP;        (returns last apparition before the current date)
           CAP < JD#   (returns last apparition before the specified Julian
                        Day Number)
           CAP < YEAR  (returns last apparition before the given integer year)

       If the number after a '<' is less than 10000, it is assumed to be
       a year integer. Otherwise, the number is taken to be a Julian Day
       Number.  If "CAP;" is specified, the search is automatically 
       recognized as being a comets-only search.

       Note that comet apparition records that are integrator propagations 
       of the same orbit epoch solution have been removed from DASTCOM3. 
       There remain instances in which the same comet may have different 
       orbit solutions. This is because measurements indicate out-gassing
       (non-gravitational forces) changed for the different approaches to 
       the Sun, requiring different orbit solutions for the same object at
       the different approach times.

    -- The CONTOUR spacecraft trajectory is being updated in Horizons as the 
        JPL navigation team releases new trajectory solutions. Type CONTOUR or
        "-200" (the spacecraft ID number) at the main prompt.

 May 26, 2002:
    -- The Horizons small-body database has been updated with 1447 spectral
        type classifications using the SMASS-II taxonomic system. This replaces
        783 Tholen-system classifications previously available.

        REFERENCE: 
         "Phase II of the Small Main-Belt Asteroid Spectroscopic Survey: 
          A Feature-Based Taxonomy", S. J. Bus, R. P. Binzel, Icarus (in press)
    -- Uranian satellites 716-720 were extended 22 years to 2024-Mar-30
        (Caliban, Sycorax, Prospero, Setebos and Stephano) 

 May 22, 2002:
    -- Elevation cut-off may now be a decimal value instead of integer.
       Confirmation output displays to the nearest 0.1 degree, but the full
       input value is used for determining table limits.

 May 17, 2002:
    -- 11 newly discovered Jovian satellites have been added (IDs 529-539).
    -- The Cassini trajectory was updated to reflect the new tour design.

 Jan 15, 2002:
    -- Asteroid and comet database updates now occur on an hourly basis. 
    -- DS-1 final trajectory, with predicts to 2004, is now on-line.

 Nov 05, 2001:
    -- Version 3.0 (NEW FUNCTIONS FOR ASTEROID AND COMETS ONLY):
         * Added 12 new statistical quantities to observer tables (#36-#40):
             RA_3sigma,  DEC_3sigma, SMAA_3sig,  SMIA_3sig, Theta,     
             Area_3sig,  POS_3sigma, RNG_3sigma, RNGRT_3sig, DOP_S-sig, 
             DOP_X-sig,  RT_delay-sig
           The above describe orbit uncertainties in the plane-of-sky.
         * New close-approach table-type:
            - Efficiently detect asteroid and comet approaches to planetary
              bodies (and Ceres, Pallas, Vesta). Computes up to 12 parameters:
                 Nominal date of approach, Body approaches, CA Dist,
                 MinDist, MaxDist, Vrel, TCA3sg (uncertainty in time of
                 close-approach), B-plane SMAA, B-plane SMIA, orientation 
                 angle, Nsigs, P_i/p (impact probability). 
         * The small-body database has been expanded to include additional
            information. Objects with a +COV notation on their data-sheet
            have covariances available, thus uncertainties can be computed.
            Displays now include orbit solution residual RMS and apparent
            magnitude (H) RMS, among other things.
         * 'TDB' (Barycentric Dynamical Time) is replaced by the preferable 
            Coordinate Time (CT) nomenclature.
    -- The L2 point (Sun & Earth-Moon Barycenter Lagrange-2) is now available
        over the time-span 1959-Dec-10 to 2020-Jan-16. To select the dynamical
        point, type "L2" or it's numeric code "392" at the main prompt. To 
        produce ephemerides with respect to L2, specify the coordinate center
        as "@L2"

 Oct 18, 2001:
    -- The L1 point (Sun & Earth-Moon Barycenter Lagrange-1) is now available
        over the time-span 1959-Dec-10 to 2020-Jan-16. To select the dynamical
        point, type "L1" or it's numeric code "391" at the main prompt. To 
        produce ephemerides with respect to L1, specify the coordinate center
        as "@L1"
    -- Version 2.93b:
        Added atmospheric refraction option to quantity #31 (observer-centered 
        apparent ecliptic longitude and latitude).

 Aug 21, 2001:
    -- Galileo spacecraft trajectory updated to include tracking data through 
        Aug 9, 2001. Predicts now extend to Sep, 2003 Jupiter impact.

 Aug 15, 2001:
    -- The Genesis spacecraft trajectory (halo orbit around L1) is now
        available on Horizons. Spacecraft ID is -47. Type that or 'Genesis'
        at the main prompt to select.

 Jul 11, 2001:
    -- Saturnian satellites 619-630 have been updated to the new SAT122
        solution of Bob Jacobson (JPL).

 Jun 26, 2001:
    -- Satellite osculating elements output by Horizons should NOT be used to 
        initialize a separate integration or extrapolation. Such elements 
        assume Keplerian motion (two point masses, etc.) which usually DOES NOT
        MATCH the kinematic model of the satellite orbit (which could be a 
        precessing ellipse, for example). One would be better off extrapolating 
        with mean orbital elements at http://ssd.jpl.nasa.gov/sat_elem.html

 Mar 28, 2001:
    -- Version 2.91
         * Dropped semi-colon requirement for single-parameter small-body 
            search.  For example, enter '2000 EE104' instead of '2000 EE104;'
            to look up a designation. Or 'A > 35' instead of 'A > 35;'.
            Multiple-parameter searches still require semi-colon separator. 
         * Removed cause of some (neutral) integration warning messages.

 Jan 25, 2001:
    -- Version 2.90.b
         North pole distance from target disk center (quantity #17) has been
         altered to use target's polar radius instead of equatorial. For 
         notably oblate planets, such as Jupiter, this can make a 1-2" 
         difference in "NP.dis". 

 Jan 10, 2001:
    -- Post-maneuver update to Stardust trajectory now on-line. Use this for
        any of the Jan 15 Earth gravity-assist flyby observations.

 Jan 06, 2001:
    -- 10 new Jovian satellites on-line: 519 (2000J2), 520 (2000J3), 
        521 (2000J4), 522 (2000J5), 523 (2000J6), 524 (2000J7), 525 (2000J8),
        526 (2000J9), 527 (2000J10), 528 (2000J11)

 Dec 29, 2000:
    -- New Saturnian satellite on-line: 630 (2000S12)

 Dec 19, 2000:
    -- New Saturnian satellite on-line: 629 (2000S11)

 Dec 10, 2000:
    -- Four new Saturnian satellites on-line: 2000S7, 2000S8, 2000S9, 2000S10.
    -- Version 2.90.a: fixed topocentric velocity output corrupted in Dec 8
        release.  Thanks to Christian Glowinski for being alert.

 Dec 08, 2000: 
    -- Version 2.90:
         * Perturbations due to small bodies (currently Ceres, Pallas & Vesta)
            were added to asteroid & comet integrator equations of motion, for 
            improved long-term accuracy.
         * Asteroid/comet integrator error tolerances tightened for long-term 
            propagation accuracy. Typical main-belt accumulated integration
            error after 400 years is ~0.5 km now. Previously was ~2-3 km.
         * GM computation improved for osculating element tables. SSB elements
            now use sum of planet-system GM's out to and including target body.
            (asteroids and comets, out to Earth). Proper barycentric mass
            parameters are now used for object motion wrt barycenter.
         * System execution speed roughly doubled again due to now completely 
            native system build on new hardware/software platform. Searches 
            that, in September, took 20 sec, now take ~1.5 seconds (one user). 

 Nov 29, 2000:
    -- Two newly-identified Saturnian satellites are available:
             623 (2000S5), 624 (2000S6).
       Other recently discovered Saturnians updated to solution SAT111:
             619 (2000S1), 620 (2000S2), 621 (2000S3), 622 (2000S4)
    -- There may be fairly rapid updates on these discovery-satellite 
         solutions that are implemented but not called out each time here. 
         See source notation in output ephemeris.
    -- As of today, Horizons has 63125 asteroids, 315 comets, 75 satellites, 
         9 planet centers and 9 system barycenters, the Sun, Solar System 
         Barycenter and 16 spacecraft. 
    -- Horizons usage summary 2000-10-15 to 2000-11-15
          Connections:               Products:
            Telnet          2827        Telnet          9954
            WWW             8982        WWW             9291
            E-mail          1347        E-mail          2334
                                        SPK obj/fil        5/5
            --------------------        --------------------
            Total(month)   13156        Total(month)   21584
           >TOTAL(Oct96)  273343       >TOTAL(Oct96)  421575
           
 Nov 28, 2000:
    -- A newly-identified Jovian satellite is available: 518 (2000J1)

 Nov 16, 2000:
    -- Orbit solutions for Uranian satellites 716-720 updated to URA055. 
       System ID codes were altered to conform to new IAU satellite numbering.

        Was:          Now is:                 Change
        -----------   ----------------------  --------------------------------
        721, 1999U3   718, Prospero (1999U3)  Different object. Formerly #721.
        719, 1999U1   719, Setebos  (1999U1)  Now named
        720, 1999U2   720, Stephano (1999U2)  Now named
        718, 1986U10     UNAVAILABLE          Not officially numbered

 Nov 13, 2000:
    -- Four new Saturnian satellites are available (SAT110 solution):	
          619 (2000S1), 620 (2000S2), 621 (2000S3), 622 (2000S4)

 Oct 25, 2000:
    -- Ephemerides for the Galilean satellites (Io, Europa, Ganymede and
         Callisto) were upgraded to the new JUP166 (JPL) solution.

 Oct 04, 2000:
    -- Server hardware/OS upgraded (new machine) for improved performance.

 Aug 18, 2000:
    -- Version 2.82 (e-mail batch files updated):
         * New true batch-mode allows e-mail request of up to 200 ephemerides 
             (or commands) within a single e-mailing. That is, the variable 
             assignment "COMMAND=" can now be a list. Example usage:

                  COMMAND= '2;' 
                           '3;' '499'
                           'A>5.2; A< 5.3'
                           'Mimas'
           
           This method is now strongly preferred over mailing in 200 separate 
           requests, as had to be done previously.

         * A list of up to 200 discrete times (JD or MJD) may now be requested 
             for ephemeris output using the new variable "TLIST=". Example:

                   TLIST= '2451454.8937833' '2451455.11256351'
                          '2451456.45576728'
                          '2451459.65778822'

           Output will occur only at the specified times, not just at fixed 
           time or angular-motion steps previously available.

           For more details on the new COMMAND and TLIST e-mail functions, see 
           descriptive comments in the updated example batch file available at 
           the FTP site:

              ftp://ssd.jpl.nasa.gov/pub/ssd/horizons_batch_example.long 

           ... or e-mail a blank message to "horizons@ssd.jpl.nasa.gov" with
           the subject "BATCH-LONG".

      -- The Galileo spacecraft and probe trajectories are now available
           ID numbers are -77 for the orbiter, -344 for the probe.

 Jul 23, 2000:
    -- Newly recognized Jupiter satellite 1999J1 (IAU Circ 7460) is now
        available through Horizons. Object code number is 517.
 
 Jul 10, 2000:
    -- Stardust and Ulysses spacecraft trajectories are available. Many thanks
        to Mark Ryne (Ulysses Navigation) for assembling the Ulysses data.
    -- Newly discovered Uranian satellites (719-721) ephemerides updated.

 Jun 14, 2000: 
    -- Version 2.81 (documentation updated)
         * A new marker has been added to observer table quantity #23, solar 
            elongation. If the field contains a /T, the target trails the Sun 
            (evening sky). If /L, the target leads the Sun (morning sky). The 
            marker is not output if the observer is a spacecraft or has no 
            rotation model.
    -- The Infrared Space Observatory (ISO) trajectory, an ESA mission, is 
         now online. 

 Jun 09, 2000:
    -- Three newly identified Uranian satellites are now available:
           1999U1 (719), 1999U2 (720), 1999U3 (721)
    -- Version 2.80.E (e-mail batch files updated)
         * Allowed ephemeris length has been doubled.
         * Long e-mailed output will no longer be segmented into so many
             pieces. Only extremely long search result output may be split.
       OBSERVER TABLES ONLY:
        |* Solar elongation cut-off is now available.
        |    Enter a minimum/maximum separation angle (in degrees). The table 
        |    will contain requested data only when target is inside bounds.
        |       Batch variable: SOLAR_ELONG= "0,180" (default is DISABLED)
        |* Optionally suppress range-rate output to obtain range only.
        |       Batch variable: SUPPRESS_RANGE_RATE= "NO" {or "YES"}
        |* Toggle units on range quantities to be either KM or AU.
        |       Batch variable: RANGE_UNITS= "AU" {or "KM"}
       TELNET ACCESS ONLY:
        |* A problem causing connection delays for those telneting in from
        |    behind a firewall has been identified and corrected.
        |* Personalized program-settings saved between sessions:
        | 
        |    Tired of plugging through the beautifully designed prompt
        |    structure to change default settings every time you connect?
        |    It's now possible to do it only once, then save the settings
        |    for future sessions.
        |
        |    Once you have gone through the prompts and defined the output, 
        |    return to the main "Horizons>" prompt. 
        |
        |      - Type "SAVE {NAME}", where {NAME} contains 1-12 characters.  
        |      - Next time you telnet to Horizons, type "LOAD {NAME}".
        |
        |    Your output preferences will then be loaded in as new defaults.
        |    The idea is to save time; you need not customize your output anew
        |    each time you return to the system. Others in your organization 
        |    can use the same pre-defined format settings by name. 
        | 
        |    What if you make a mistake or want to change a setting later?
        |    Not to worry.
        |
        |    DELETE a macro with command "DELETE {NAME}". Or change specific
        |    settings manually and replace the stored  macro with a SAVE to
        |    an existing name.  Delete and replace operations require input of 
        |    a confirming password. LOAD does not. Thus, anyone can use your
        |    settings if they know the macro name. Only those who know the
        |    password can change or delete a macro.
        |
        |    Note that start/stop dates are also saved in the macro, as is
        |    observing location, etc. You need only load the macro and select
        |    the target. Remaining defaults will be as defined in the format 
        |    macro. If the macro is for an individual (personal use), you may 
        |    want to set the e-mail address. Otherwise don't, so users of the
        |    macro will be prompted for it in the future.
        |
        |    A macro may be loaded, then specific settings overruled by
        |    responding to the program prompts.
        |
        |    For example, if your last table prior to saving the macro was a 
        |    "vector" table, that table type will be saved as the default. 
        |    Settings for the other table types are saved as well so, to access
        |    them, you would manually respond to the prompt requesting table 
        |    type, over-riding the macro's "vector" default on that issue.
        |    Start and stop times are also macro settings that may commonly be 
        |    overruled as necessary. 
        |
        |    For macro names, I recommend something clean and logical:
        |      "OBS670-1" for macro #1 for Observatory Code 670, etc. 
        |
        |    ... but call them what you want.
        |
        |    The use of macros may make it less likely to stumble upon new
        |    capabilities as they are added, though they will described here
        |    and in the system documentation, as appropriate. 

 Jun 01, 2000:
    -- Version 2.80.D (e-mail batch files updated)
         * Designation & name search time reduced by half. Faster server  
             hardware will be obtained later this year.
         * New format options for ELEMENT and VECTOR tables (telnet & email).
             - Optionally request labelling on or off for each output number. 
                Batch variable: ELM_LABELS = 'YES' (or 'NO')
                                VEC_LABELS = 'NO'  (or 'YES')
             - Perihelion Time (Tp, ELEMENT table) may now optionally be
                an absolute Julian day number OR relative to element Epoch.
                Batch variable: TP_TYPE = 'ABSOLUTE' (or 'RELATIVE')

 May 17, 2000:
    -- Send any desired system changes to "Jon.Giorgini@jpl.nasa.gov". 
        Next year, if not sooner, there will be resources available for 
        major revisions or extensions to the system. (NOTE: the database
        of asteroids/comets is routinely updated ~ daily, as always) 
    -- System activity last month:
         Horizons usage summary 2000-04-15 to 2000-05-15
          Connections:               Products:
           Telnet          2385        Telnet          7067
           WWW            14497        WWW            14790
           E-mail          2286        E-mail          4496
                                       SPK obj/fil      678/678
           --------------------        --------------------
           Total(month)   19168        Total(month)   27031
          >TOTAL(Oct96)  217149       >TOTAL(Oct96)  322609

 Apr 24, 2000:
    -- Version 2.80.C
          Special-case magnitude computations implemented for comets:
          2P/Encke, 95P/Chiron, 107P/Wilson-Harrington, 133P/Elst-Pizarro
    -- It's now possible to search on the packed form (MPC) of an object's
        primary designation. For example, "DES= K00E26H;" is the same as a 
        search for "DES= 2000 EH26;".
    -- Trans-Neptunian objects (a >= 30 AU) are now in the database.
    -- Last month's usage (typical except for large # SPK files requested):

            Horizons usage summary 2000-03-15 to 2000-04-15
             Connections:               Products:
               Telnet          2961        Telnet          7542
               WWW             4794        WWW             5004
               E-mail           616        E-mail          1054
                                           SPK obj/fil     1375/1375
               --------------------        --------------------
               Total(month)    8371        Total(month)   14975
              >TOTAL(Oct96)  197981       >TOTAL(Oct96)  295578

 Mar 11, 2000:
    -- The NEAR spacecraft trajectory has been added. It covers 1996 to the
        present, being a concatenation of JPL navigation deliveries to the
        Project with planning prediction to May 2000. 

        NEAR-centered or Eros-centered output may be requested. For example, 
        select 2000433 as the target (the SPICE ID of Eros) & use "@NEAR" for 
        the coordinate center to obtain the lat/long of the intercept point 
        on the reference surface for a vector directed from NEAR to the 
        center of Eros.  Note this is NOT the "sub-spacecraft" point, which
        would be the point on Eros closest to the spacecraft.

    -- Trajectories for Voyager 1 & 2 from launch through 2049 are now
        available. Type "Voyager 1" (-31) or "Voyager 2" (-32).

              Name       ID#    START          END
              --------- -----   -----------    -----------
              NEAR       -93    1996-Jun-01    2000-May-04
              Voyager 1  -31    1977-Sep-06    2049-Dec-30
              Voyager 2  -32    1977-Aug-21    2049-Dec-30

 Jan 14, 2000:
    -- There is an example script on the FTP site that demonstrates how to
       transparently automate Horizons small-body SPK file production: 

                   ftp://ssd.jpl.nasa.gov/pub/ssd/smb_spk

       The method can be adapted to automate other system activity, allowing 
       Horizons to be embedded in scripts or programs running at your site.
       To install the "Expect" language the script is written in, also download
       
                   ftp://ssd.jpl.nasa.gov/pub/ssd/expect-5.18.tar.gz
                   ftp://ssd.jpl.nasa.gov/pub/ssd/tcl7.4.tar.gz

       "gunzip" the files and follow installation directions.
           
 Sep 09, 1999: 
    -- The Chandra X-ray Observatory is now available. Type "Chandra" at the
       main prompt or select by menu on the web. The trajectory will be updated
       monthly. Many thanks to George Lewis (JPL) for securing authorization 
       to make this spacecraft available here.

 Aug 24, 1999:
    -- Newly identified Uranian satellite 1986U10 is now available over the
       time span 1980-JAN-1 to 2010-JAN-3. Type "1986U10" or "718" at main
       prompt to select the object.

 Aug 03, 1999:
    -- The Cassini trajectory was updated to the new reference for the Earth
       flyby Aug 18. The change is for Earth orbiting debris collision 
       avoidance.  Earth periapsis time is 14 seconds later than the nominal 
       to increase the miss distance of the worst "bad guy" from about 3-4 km 
       to about 90 km.

 Jul 17, 1999:
    -- The DS-1 trajectory has been updated to the current Nav Team release 
       in preparation for the 1992 KD flyby Jul 28, 1999.  
    -- Asteroid 1992 KD has been redefined as a major body, so it may be used 
       as an "observing" center to generate tables as seen from the asteroid 
       when DS-1 flys by.
       
 Jul 16, 1999:
    -- Version 2.80.A
         Apparent visual magnitude and solar phase angle correction parameters
         used by Horizons for the Galilean satellites (Io, Europa, Ganymede,
         Callisto) have been changed to those published in "Planetary 
         Satellites" (ed. Burns,1977), Table 16.2 & 16.4 (Morrison & Morrison).
 
         Jay Goguen (JPL) noted the Ganymedian magnitudes output by Horizons
         were off. This was traced to an erroneous phase correction coefficient
         published in the "Explanatory Supplement to the Astronomical Almanac",
         USNO, Table 7.52.1 (1992), which Horizons had previously incorporated.
    -- To request heliocentric vectors, enter "@sun" when prompted for the
       coordinate center.

 Jun 28, 1999:
    -- Version 2.80 (MAJOR EXTENSION, documentation revised):
        A) The system has been generalized to allow observing sites on
           other planets, satellites and spacecraft. 
        B) Users may define their own sites on other planets and satellites;
           Example applications: 
             - when does the Earth rise as seen from a site on Io?
             - what are the eclipse circumstances of Deimos as seen from a
                landing site on Phobos?
             - When is sun rise as seen from the Viking 1 landing site?
             - What is the azimuth and elevation of asteroid Ceres from
                a site on the Moon (or Europa)?
        C) A database of spacecraft landing sites on Venus, the Moon and Mars
           has been predefined. 
        D) New observer table quantities:
             #34: Local Apparent Solar Time
             #35: Instantaneous Earth to Site Light Time
        E) This is a big change. Recommend reviewing documentation of new
           capabilities (section#4): 
                ftp://ssd.jpl.nasa.gov/pub/ssd/Horizons_doc.ps

 Apr 19, 1999:
    -- Version 2.79 (documentation updated):
        A) Observer tables are now generated 1 to 2.8 times faster, depending
            on the quantities requested, due to restructuring of the program.
        B) Program has been updated to use current IAU 1997 rotational & 
            cartographic coordinate models.
        C) Reminder: as always, one can obtain output at less than 1 minute 
            intervals (telnet & e-mail interfaces only) by specifying a time
            step WITHOUT UNITS. For example, "10" will output at 10 evenly
            spaced intervals between the start and stop. If start and stop are
            one hour apart (3600 seconds), then "240" will output at 15 second 
            intervals (3600/15 = 240 intervals). Rise/set and satellite eclipse
            circumstances may not be accurate to less than a minute since 
            factors such as the primary's oblateness and atmosphere are not 
            currently modelled. 

 Apr 02, 1999:
    -- Version 2.78c (documentation updated):
        For observer tables, galactic latitude (#33) is now available. 

 Mar 18, 1999:
    -- SYSTEM MAY BE DOWN: Within the span Fri Mar 19, 4:00 p.m. to Sat Mar 20 
       Noon (PST) for building maintenance power-shut-off.
    -- Saturn satellites Atlas (615), Prometheus (616) & Pandora (617) were 
       extended in time to 1980-Jan-1 through 2009-Dec-19.
    -- Database inclusion: 

         There have been queries about which objects are included in the 
         system's database of asteroids and comets.  Excluded are: single 
         opposition asteroids with observational data arcs less than 30 
         days, unless they are NEO's, "PHA's" or radar targets (which ARE 
         included). Everything else is in. 

         Except for "PHA's", which are usually included within 24 hours of 
         announcement, there can be a delay of a few days to a couple weeks 
         before newly discovered objects (that meet the filter) criteria are 
         added. The database is updated almost daily with new objects and 
         orbit solutions. 

 Mar 10, 1999:
    -- SYSTEM WILL BE DOWN: Fri Mar 12 in the afternoon (PST) for ~3 hrs 
       to perform Y2K operating system upgrade.
    -- Uranian satellites Caliban (716) and Sycorax (717) have been updated
       to the new URA045 solution from Bob Jacobson (JPL):

         Ephemeris Accuracy (km,sec) - 1 sigma:
            Name               Radial    Downtrack       Normal       Period
            Caliban          2000.000    10000.000     3000.000  1500.000000
            Sycorax         15000.000    30000.000     6000.000  6000.000000
         Chebyshev interpolation accuracy: 600 m

 Mar 05, 1999:
    -- Version 2.78b:
        A) E-mail batch mode variable type inconsistencies were eliminated.
        B) An automatic filter was installed to permit processing of e-mail 
           batch files sent by some mailing systems (AOL), that insert extra 
           characters in the command file before transmission. If you had
           trouble mailing commands from AOL in the past, try again now.
           
 Feb 23, 1999:
    -- Spacecraft ephemerides
         New     : Lunar Prospector (transfer & LOI only), Planet-B
         Updated : NEAR, DS-1
             
 Feb 11, 1999:
    -- All satellite and planet-center ephemerides have been updated to a 
       DE-405 basis. For a PostScript table listed current orbit determination 
       uncertainties for all satellite ephemerides, see: 

          ftp://ssd.jpl.nasa.gov/pub/ssd/satellite_accuracy_table.ps

 Jan 03, 1999:
    -- Version 2.78:
        A) Target body North Pole RA & DEC were added as requestable observer 
            table output (quantity #32).
        B) Phase corrections are now included for Galilean satellite apparent
            magnitude calculations.
    -- The Cassini trajectory was updated from May 1998 -> 2004 encounter.

 Dec 07, 1998:
    -- The on-line NEAR spacecraft trajectory has been updated through Dec 3 
       and includes predicted rendevous and orbit insertions maneuvers until
       Jan 15.  It is possible to compute Eros centered vector tables.

 Nov 04, 1998:
    -- The trajectory for Deep Space 1 (DS-1 spacecraft) has been added. By
       telnet or e-mail, request "DS1" or "Deep", etc., at the prompt. For
       the web interface, a menu line will be added shortly.

 Sep 24, 1998:
    -- Version 2.77 (documentation updated, batch/email command files updated):
        A) New time-varying output mode for OBSERVER TABLES via telnet/e-mail.
            Instead of producing a table at uniform time steps, output can be 
            at possibly varying time-steps based on when the object has moved 
            at least #### arcsec in the plane-of-sky of the observer. When 
            specifying output STEP_SIZE, respond with "var ####", where #### 
            is an integer from 60 to 3600 arcsec.
        B) New 'PAGE' command at main-prompt (telnet). Turns paging ON or OFF.
        C) New "[A]gain" option after ephemeris display. Returns to last data 
            screen prompt, permitting generation of another ephemeris for the 
            same object without having to select the object again.
        D) Additional digit for app. mag. & surface brightness (now 10^-2).

 Aug 28, 1998:
    -- Version 2.76 (documentation updated):
        A) New directives for small-body searches (telnet/e-mail interfaces):
             LIST;   (display values of matching parameters)
             AST;    (limit search to asteroids only)
             COM;    (limit search to comets only)
        B) "LIST" is also a new toggle switch from the main command prompt,
           setting the display-parameter behavior for subsequent searches.
 
        EXAMPLE: "QR < 1; ADIST < 1.1; LIST;" will search for 
           all comets & asteroids with perihelion distance less than 1 AU,
           aphelion distance less than 1.1 AU and SHOW the numeric values
           for the objects that match.

 Aug 24, 1998:
    -- Satellite orbits UPDATED (additional obs. data) & EXTENDED in time for:
        *Jupiter: Amalthea (505), Thebe (514), Adrastea (515), Metis (516)
        *Uranus : Cordelia (706), Ophelia (707), Bianca (708), Cressida (709),
                  Desdemona (710), Juliet (711), Portia (712), Rosalind (713),
                  Belinda (714), Puck (715)
       Satellite orbits EXTENDED in time for:
        *Saturn : Janus (610), Epimetheus (611), Helene (612), Telesto (613),
                  Calypso (614), Atlas (615), Prometheus (616), Pandora (617), 
                  Pan (618)
        *Neptune: Naiad (803), Thalassa (804), Despina (805), Galatea (806), 
                  Larissa (807), Proteus (808)
    -- The Cassini baseline trajectory was updated for the time after Venus 
       flyby through Saturn encounter (1998-MAY-03 12:00 to 2004-JUL-01 12:00).
    -- The announced +1 leap-second for Jan 1, 1999 is now reflected in UT 
       output.
           
 Aug 13, 1998:
    -- Version 2.75:
       A) Due to increased rate of asteroid numberings, it was necessary to
          restructure the small-body database. There are now more than 21000
          objects available. Record number assignments are:

    Record # range    Object type
    ----------------  -------------------------------------------------------
         1 -> 100000  Reserved for NUMBERED asteroids (record # = asteroid #)
    100001 -> 200000  Reserved for UNNUMBERED asteroids
    200001 -> 300000  Reserved for COMET APPARITIONS

       B) Search behavior was altered slightly. For NAME, COMNAM, ASTNAM or
          DES searches, terminating the match string with a '*' will look for
          a sub-string match. If there is no '*', an exact match is required.

       Example:   DES=1998 ML*;  (match any designation containing "1998 ML")
                  DES=1998 ML;   (match EXACT designation "1998 ML")
 
         As always, the '*' must be in the last position and does NOT control
         any sort of specific pattern specification.

 Aug 10, 1998:
    -- Version 2.74:
       A) Additional observer table quantity (#31):
             Observer-centered true ecliptic-of-date latitude & longitude
       B) Old observer table quantity (#18) CHANGED to ... geometric 
          heliocentric ecliptic longitude & latitude at the time light 
          reflected from the object to be observed at print-time. 
       C) The small-body integrator was upgraded. 

 Jul 15, 1998:
    -- Recently discovered Uranian satellites "Caliban" (S/1997U1) and 
       "Sycorax" (S/1997U2) are now available. No rotation or brightness models
       are currently implemented.

 Jun 25, 1998:
    -- This system will be unavailable Friday, Jun 26, 5:00 p.m. to at least
       Saturday, Jun 27, 8:00 p.m. due to building maintenance power shut-down.

 Jun 14, 1998:
    -- The telnet screen display no longer wraps lines; instead, use the arrow 
       keys to scroll the display left/right (and up/down). This should make 
       large tables easier to read by maintaining the columns.

 May 22, 1998:
    -- Version 2.73:
         A source of numerical noise was eliminated. The improved computational
       accuracy affects some comet & asteroid integrated positions at a level 
       less than 10 meters.

 May 19, 1998:
    -- Satellite orbital updates from Bob Jacobson (JPL):
         Phobos (401), Deimos (402), 
         Phoebe (609),
         Triton (801), Nereid (802), Neptune (899).

 May 15, 1998:
    -- Version 2.72 (documentation updated):
         Satellite visibility (eclipse) codes now indicate whether the object
         is also in occultation, during the eclipse, by using capital letters:

      /t = Transitting primary body disk, /O = Occulted by primary body disk,
      /p = Partial umbral eclipse,        /P = Occulted partial umbral eclipse,
      /u = Total umbral eclipse,          /U = Occulted total umbral eclipse,
      /- = Target is the primary body,    /* = None of above ("free and clear")

 Apr 28, 1998:
    -- Version 2.71 (documentation updated): 
        * Planetographic latitudes are now that of the center of the target 
          disk, not the intersection of shortest normal vector (altitude) with 
          the reference ellipsoid that was previously output. This should be 
          more useful to optical observers. The prior output point was more 
          relevant to radar and spacecraft.
        * Unnecessary keys are no longer embedded in output. $$SOE & $$EOE 
          remain to mark the start and end of ephemeris data.

 Mar 03, 1998:
    -- Version 2.70:
        Review latest documentation for description of new capabilities:
                ftp://ssd.jpl.nasa.gov/pub/ssd/Horizons_doc.ps

        Primary changes:
         * SPK binary file output option (comets/asteroids, telnet only).
         * Local civil time for observer tables (time zones).
         * TT & UT time scales now toggled only with START time specification.
         * GEOMETRIC state light-times now = geometric_range/speed-of-light.
         * Example batch mode files updated (new: TIME_ZONE, gone: TIME_TYPE)

 Jan 20, 1998:
    -- Observe the NEAR spacecraft on its Earth flyby Jan 22-23.
       The trajectory is now on-line; compute ephemerides for your site. 
       Type "NEAR" at the main prompt.

 Jan 12, 1998:
    -- Version 2.60:
        Review latest documentation for description of new capabilities:
                ftp://ssd.jpl.nasa.gov/pub/ssd/Horizons_doc.ps

        Primary changes:
         * Solar System models extended to cover 3000 B.C. to A.D. 3000 (Sun, 
            Moon, planet barycenters and their equivalents from DE-406/LE-406).
         * UT prior to 1972, TDB-UT (Delta-T) output option on observer tables.
         * Heliocentric ecliptic lat/long now with respect to ecliptic of date
            at the instant light leaves object to be observed at print time.
         * Behavior change on major-body selection; specifying a planet name
            will not be considered unique if there is a barycenter available. 
            Use the unique numeric ID numbers when possible. 
         * New rise-transit-set control options.
         * Miscellaneous output format changes; LC headers, geodetic station
            coordinates confirmed, first column space for "BC" marker. 
         * More digits output for 1-way light-time, phase & solar elongation
            angles.

 Nov 07, 1997:
    -- The nominal Cassini spacecraft trajectory through 2004 is available. 
       Type "Cassini" at the main prompt.
    -- Short-cut reminders:
         * Move backward through the prompts by typing "-".
         * Quit from any prompt by entering 'q'.
         * To use a default or previously entered value, press return.
         * After selecting an object, enter "e+" to produce an ephemeris
           format like the last one, without any prompting. 

 Nov 03, 1997:
    -- The comet and asteroid database (DASTCOM3) was updated with more than
       750 asteroid rotation periods received from Alan Harris (JPL). Binary 
       and tumbling asteroids were noted where appropriate.

 Oct 18, 1997:
    -- Units on RA & DEC rates have been changed to arcsec/HOUR.

 Oct 10, 1997:
    -- The latest solar system model of DE-405 replaces DE-403.  

 Oct 02, 1997:
    -- Version 2.51:
       Observer tables
         -- Constellation identification added as option #29. This displays
            a three character abbreviation for the name of the constellation
            (IAU, 1930) background for the target's astrometric position.
         -- Documentation updated
 
 Sep 23, 1997:
    -- The rotation angle W for Jupiter's satellite Metis in the 1994 IAU
       report (Davies et al, 1996) is incorrect. In the J2000 system, the 
       initial value of Wo at epoch J2000 should be 346.09 deg rather than
       the published 355.09 degrees (JPL IOM 312.F-97-059). This program 
       now uses the recently corrected value.
    -- RTS-only print was generalized to work for all cases, but will now
       take much longer to complete.

 Sep 04, 1997:
    -- Version 2.50 changes:
       Observer tables 
        - Specify start times to second or fractional seconds level.
        - Quantity #6 (RA/DEC offset) replaced with X & Y satellite 
            differential coordinates AND satellite position angle.
        - New rise/transit/set indicator when print step less than 30 minutes.
        - New rise/transit/set print-ONLY mode with 1 minute resolution.
       Searching
        - New keyword: "COMNUM" (e.g. COMNUM = 1; to find numbered comet 1).
        - Designations now appear in search results (if stored in DASTCOM3).
       Vector tables
        - User-specified units retained between runs.
        - Start times may be specified to fractional second precision.
       Miscellaneous
        - Comet designations shown for record display.
        - Example batch files updated with new controls.   
        - On-line documentation updated, expanded.
          
 Jul 25, 1997:
    -- Version 2.01
         It is now possible to enter main-prompt commands at the data screen
       display prompt. Practical upshot: if your search returns a list of
       objects, you can pick out the one you want without having to go back to
       the main command line. Just enter the record number -> 2; (for example)
       A new search formulation could be entered as well.

    -- A subset of Horizons can be accessed, along with some other nifty
       observer tools you should check out (sky search & discovery 
       confirmation), by WEB PAGE (!). Find out what's visible from your
       location at any given time and check if there is any known object
       at some location:

                          http://ssd.jpl.nasa.gov/

 Jul 21, 1997:
    -- Version 2.00:
        a) New batch mode; users may now run Horizons NON-INTERACTIVELY by 
           e-mail. To start, send mail to "horizons@ssd.jpl.nasa.gov" with 
           subject "HORIZONS-BATCH-LONG". A commented run-stream will be sent
           back. Edit the text file & mail back with subject "JOB-SUBMITTAL".
        b) Vector and osculating element output can now be with respect to
           the following reference planes: Ecliptic of J2000 or B1950, 
           Central body mean-equator of-date or Equator of reference frame 
           (J2000 or B1950). 
        c) Telnet interface now recognizes "backspace" and "delete" keys as
           being equivalent.
        d) All documentation has been updated.

 Jun 13, 1997:
    -- Switch-over to new server is complete. 

 Mar 04, 1997:
    -- IMPORTANT! New access address: "ssd.jpl.nasa.gov 6775". Please replace
       any macros or aliases that connect using any other address. This program
       will be migrated to a new, faster machine in the months ahead. At some
       point, the old address will no longer work, so switch now and make a
       note in your documentation. Postscript doc. file has been updated. 
    -- New observing sites have been added to the station location database.
    -- The asteroid/comet database has been updated with many new objects.

 Feb 17, 1997:
    -- VERSION 1.12 PROGRAM UPDATE
         NEW QUANTITY for small-body observer tables: orbit plane angle (#28)
         (Angle between observer and target orbital plane, measured from center
         of target at the moment light seen at observation time leaves the 
         target.  Positive values indicate observer is above the object's 
         orbital plane, in the direction of J2000 +z axis.)

 Jan 20, 1997:
    -- VERSION 1.11 PROGRAM UPDATE
         Three more digits of precision were added to sub-observer/sub-solar
         latitude and longitude output (for the Moon only). This reflects the
         published accuracy in the 1994 IAU Lunar model.
    -- The comet/asteroid database monthly update was performed.

 Dec 16, 1996: 
    -- The comet and asteroid database was updated with new objects and some
       improved orbits. Normally done monthly, this particular update also 
       includes 7000 newly determined magnitude parameters and several dozen 
       comet orbit updates.

    -- VERSION 1.10 PROGRAM UPDATE
         a) Now allows observer tables for planetary barycenter targets.
         b) New quick-run option. After setting up & producing first table, 
            similar tables are automatically produced by responding "e+" at 
            the prompt after the object's data screen. This skips prompting 
            for characteristics previously specified (date range, output 
            interval, etc.) and immediately produces a table format like the 
            last one you defined. 
         c) Alternatively, you can step through each prompt, hitting a blank
            carriage-return to use the previously input value.
         d) Confirmation of e-mail address on initial input. 

 Oct 30, 1996:
    -- Try this search to get a list of comets reaching perihelion in the first
       half of 1997:     CALTP > 19970101.; CALTP < 19970701.; M1 > -10.;

 Oct 29, 1996:
    -- Welcome new user!  We hope this system is useful to you. Feedback is
       important. It will be used when considering additional capabilities. 
       Send to Jon.D.Giorgini@jpl.nasa.gov

    -- A post-script version of primary documentation is stored in the system's
       anonymous ftp directory 
 
                ftp://ssd.jpl.nasa.gov:/pub/ssd/Horizons_doc.ps

 Oct 22, 1996: 
    -- Horizons will be made available to the astronomical community at the
       DPS meeting in Tucson this week. The abstract may be referenced as:

         Giorgini, J.D., Yeomans, D.K., Chamberlin, A.B., Chodas, P.W.,
         Jacobson, R.A., Keesey, M.S., Lieske, J.H., Ostro, S.J., 
         Standish, E.M., Wimberly, R.N., "JPL's On-Line Solar System Data 
         Service", Bulletin of the American Astronomical Society, Vol 28, 
         No. 3, p. 1158, 1996.

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