API VERSION: 1.2 API SOURCE: NASA/JPL Horizons API ******************************************************************************* Revised: Dec 06, 2024 TESS / (Earth) -95 https://tess.gsfc.nasa.gov/index.html http://spaceflight101.com/tess/tess-orbit-design/ BACKGROUND: The NASA Transiting Exoplanet Survey Satellite (TESS) mission is to detect exoplanets transiting nearby bright stars, targets for followup characterization with large ground telescopes such as the Hubble Space Telescope and the future James Webb Space Telescope. Launched : 2018-Apr-18 22:51 UTC Launch vehicle : Falcon 9 Block 4 Launch site : SLC-40, Cape Canaveral Payload mass : 362 kg Ascent duration : 49 minutes, then TESS deployment A SpaceX Falcon 9 launched the 362-kilogram TESS spacecraft into a Suprasynchronous Transfer Orbit of 200 by 270,000 kilometers at an inclination of 28.5 degrees. The operational orbit chosen for TESS is a highly eccentric, 2:1 lunar resonance orbit of 108,400 by 376,300 kilometers at an inclination of 37 degrees, timed so that the spacecraft reaches apogee with the moon at a phasing of 90 degrees. 11 maneuvering engine burns, 3.5 phasing loops, and a lunar flyby will be used during the first 60 days to go from the inital transfer orbit to the operational orbit. TESS is designed to: - Monitor 200,000 nearby stars for planets - Detect and characterize Earth and Super-Earth size planets - Cover 400X larger sky area than Kepler - Span stellar spectral types of F5 to M5 Transiting exoplanets allow determination of the following: - Fundamental properties: mass, radius, orbit - Dynamics: planet-planet interactions, mutual inclinations, moons, tides - Atmospheric composition & structure: transmission spectrum, emission spectrum, MISSION OVERVIEW: All-sky, two year photometric exoplanet discovery mission. TESS will tile the sky with 26 observation sectors: - At least 27 days staring at each 24 deg. x 96 deg. sector - Brightest 100,000 stars at 1-minute cadence - Full frame images with 30-minute cadence - Map Northern hemisphere in first year - Map Southern hemisphere in second year - Sectors overlap at ecliptic poles for sensitivity to smaller and longer period planets in JWST Continuous Viewing Zone (CVZ) TESS observes from unique High Earth Orbit (HEO): - Unobstructed view for continuous observation - Two 13.7 day orbits per observation sector - Stable 2:1 resonance with Moon's orbit (P/2) - Thermally stable, low-radiation SPACECRAFT: Designed for photometric stability. Heritage Orbital LEOStar-2 spacecraft bus: - 3-axis stabilized pointing, with <= 3 arcsecong performance - Two-headed star tracker; 4 wheel zero-momentum system - 400W single-axis articulating solar array - Passive thermal control - Mono-propellant propulsion system - Ka-band 100 Mbps science downlink - Hexagonal 3.9 x 1.2 x 1.5 meter dimensions when fully deployed - Two 1.1 x 0.89 m solar panels SCIENCE INSTRUMENT: Four wide field-of-view CCD cameras. Each of the four cameras has: - 24 deg. x 24 deg. Field-of-View - 100 mm effective pupil diameter - Lens assembly with 7 optical elements - Athermal design - 600nm - 1000nm bandpass - 16.8 Megapixel, low-noise, low-power, MIT Lincoln Lab CCID-80 detector Trajectory: Post-launch trajectory (starts after launch ascent, L+00:49 min.). Concatenated short-term tag-up predictions, each covering ~3-4 days: Last tracking data used is 2024-Dec-01, predicts thereafter. Trajectory name Start (TDB) Stop (TDB) ------------------------------------ ----------------- ----------------- Concatenated trajectory files (615) 2018-Apr-18 23:37 2026-Jun-03 13:00 ******************************************************************************* ******************************************************************************* Ephemeris / API_USER Thu Dec 12 03:20:36 2024 Pasadena, USA / Horizons ******************************************************************************* Target body name: TESS (spacecraft) (-95) {source: TESS_merged} Center body name: Earth (399) {source: TESS_merged} Center-site name: SATINO Remote Observatory, Haute Provence ******************************************************************************* Start time : A.D. 2024-Nov-30 00:00:00.0000 UT Stop time : A.D. 2024-Dec-01 00:00:00.0000 UT Step-size : 10 minutes ******************************************************************************* Target pole/equ : undefined Target radii : undefined Center geodetic : 5.7124, 43.9320269, .703985 {E-lon(deg),Lat(deg),Alt(km)} Center cylindric: 5.7124, 4601.22659, 4403.14405 {E-lon(deg),Dxy(km),Dz(km)} Center pole/equ : ITRF93 {East-longitude positive} Center radii : 6378.137, 6378.137, 6356.752 km {Equator_a, b, pole_c} Target primary : Earth Vis. interferer : MOON (R_eq= 1737.400) km {source: DE441} Rel. light bend : Sun {source: TESS_merged} Rel. lght bnd GM: 1.3271E+11 km^3/s^2 Atmos refraction: NO (AIRLESS) RA format : HMS Time format : CAL Calendar mode : Mixed Julian/Gregorian RTS-only print : NO EOP file : eop.241211.p250309 EOP coverage : DATA-BASED 1962-JAN-20 TO 2024-DEC-11. PREDICTS-> 2025-MAR-08 Units conversion: 1 au= 149597870.700 km, c= 299792.458 km/s, 1 day= 86400.0 s Table cut-offs 1: Elevation ( 0.0deg=YES),Airmass (>38.000=NO), Daylight (YES) Table cut-offs 2: Solar elongation ( 12.0,180.0=YES),Local Hour Angle( 0.0=NO ) Table cut-offs 3: RA/DEC angular rate ( 0.0=NO ) *************************************************************************************************************************************************************************************************************************************************** Date__(UT)__HR:MN R.A._____(ICRF)_____DEC Azi____(a-app)___Elev APmag S-brt r rdot delta deldot S-O-T /r S-T-O T-O-M/MN_Illu% RA_3sigma DEC_3sigma Sky_motion Sky_mot_PA RelVel-ANG *************************************************************************************************************************************************************************************************************************************************** $$SOE 2024-Nov-30 00:00 02 00 02.97 -32 23 30.2 216.633013 3.542342 n.a. n.a. 0.987257643792 0.3406280 0.00215813033095 -0.0280760 115.8832 /T 64.0040 121.5/ 1.6154 n.a. n.a. 31.472439 26.208291 -1.957742 2024-Nov-30 00:10 02 00 14.07 -32 18 46.6 218.455731 2.529833 n.a. n.a. 0.987259008208 0.3397506 0.00215803308228 -0.0204730 115.9647 /T 63.9226 121.5/ 1.5939 n.a. n.a. 31.841291 26.671480 -1.411116 2024-Nov-30 00:20 02 00 25.47 -32 14 00.8 220.252813 1.473557 n.a. n.a. 0.987260369098 0.3388695 0.00215796561956 -0.0132265 116.0473 /T 63.8401 121.6/ 1.5727 n.a. n.a. 32.210129 27.157110 -0.900994 2024-Nov-30 00:30 02 00 37.18 -32 09 13.0 222.024478 0.375245 n.a. n.a. 0.987261726447 0.3379849 0.00215792648253 -0.0063515 116.1310 /T 63.7565 121.6/ 1.5518 n.a. n.a. 32.578729 27.663425 -0.427304 >..... Elevation Cut-off Requested .....< 2024-Nov-30 17:20 Ar 02 36 28.30 -24 54 49.2 125.589437 -0.034908 n.a. n.a. 0.987377862196 0.2283448 0.00205270366265 -0.5826730 126.0946 /T 53.8090 126.2/ 0.5322 n.a. n.a. 28.819958 38.113742 -39.17191 2024-Nov-30 17:30 A 02 36 41.17 -24 51 01.3 127.264060 1.435265 n.a. n.a. 0.987378775408 0.2270354 0.00205037571713 -0.5780338 126.1696 /T 53.7342 126.3/ 0.5234 n.a. n.a. 28.656435 37.126874 -39.13916 2024-Nov-30 17:40 A 02 36 53.67 -24 47 11.6 128.968571 2.875882 n.a. n.a. 0.987379683359 0.2257212 0.00204806736270 -0.5729059 126.2442 /T 53.6598 126.3/ 0.5146 n.a. n.a. 28.514729 36.135558 -39.05991 2024-Nov-30 17:50 02 37 05.81 -24 43 20.1 130.704554 4.285108 n.a. n.a. 0.987380586029 0.2244020 0.00204578054033 -0.5672990 126.3186 /T 53.5856 126.3/ 0.5058 n.a. n.a. 28.395153 35.143632 -38.93342 2024-Nov-30 18:00 02 37 17.61 -24 39 26.7 132.473511 5.661039 n.a. n.a. 0.987381483398 0.2230779 0.00204351714953 -0.5612241 126.3927 /T 53.5117 126.4/ 0.4969 n.a. n.a. 28.297901 34.155050 -38.75912 2024-Nov-30 18:10 02 37 29.07 -24 35 31.3 134.276851 7.001697 n.a. n.a. 0.987382375446 0.2217489 0.00204127904456 -0.5546928 126.4666 /T 53.4379 126.4/ 0.4881 n.a. n.a. 28.223045 33.173830 -38.53666 2024-Nov-30 18:20 02 37 40.20 -24 31 33.7 136.115871 8.305032 n.a. n.a. 0.987383262154 0.2204149 0.00203906803076 -0.5477178 126.5404 /T 53.3644 126.4/ 0.4792 n.a. n.a. 28.170533 32.204011 -38.26592 2024-Nov-30 18:30 02 37 51.02 -24 27 34.0 137.991741 9.568929 n.a. n.a. 0.987384143502 0.2190759 0.00203688586085 -0.5403126 126.6140 /T 53.2909 126.5/ 0.4703 n.a. n.a. 28.140195 31.249605 -37.94699 2024-Nov-30 18:40 02 38 01.53 -24 23 32.1 139.905482 10.791209 n.a. n.a. 0.987385019469 0.2177319 0.00203473423139 -0.5324918 126.6876 /T 53.2176 126.5/ 0.4615 n.a. n.a. 28.131746 30.314548 -37.58022 2024-Nov-30 18:50 02 38 11.75 -24 19 27.8 141.857946 11.969637 n.a. n.a. 0.987385890035 0.2163828 0.00203261477934 -0.5242706 126.7611 /T 53.1442 126.5/ 0.4527 n.a. n.a. 28.144792 29.402654 -37.16620 2024-Nov-30 19:00 02 38 21.69 -24 15 21.2 143.849793 13.101925 n.a. n.a. 0.987386755181 0.2150287 0.00203052907863 -0.5156651 126.8346 /T 53.0709 126.6/ 0.4439 n.a. n.a. 28.178838 28.517573 -36.70573 2024-Nov-30 19:10 02 38 31.37 -24 11 12.2 145.881465 14.185750 n.a. n.a. 0.987387614885 0.2136696 0.00202847863692 -0.5066922 126.9082 /T 52.9975 126.6/ 0.4351 n.a. n.a. 28.233298 27.662754 -36.19989 2024-Nov-30 19:20 02 38 40.80 -24 07 00.7 147.953163 15.218757 n.a. n.a. 0.987388469129 0.2123054 0.00202646489244 -0.4973697 126.9818 /T 52.9241 126.6/ 0.4264 n.a. n.a. 28.307503 26.841411 -35.64997 2024-Nov-30 19:30 02 38 49.99 -24 02 46.6 150.064820 16.198579 n.a. n.a. 0.987389317890 0.2109361 0.00202448921096 -0.4877159 127.0556 /T 52.8505 126.7/ 0.4177 n.a. n.a. 28.400715 26.056499 -35.05751 2024-Nov-30 19:40 02 38 58.96 -23 58 30.0 152.216076 17.122848 n.a. n.a. 0.987390161149 0.2095616 0.00202255288286 -0.4777501 127.1295 /T 52.7767 126.7/ 0.4091 n.a. n.a. 28.512137 25.310687 -34.42423 2024-Nov-30 19:50 02 39 07.72 -23 54 10.7 154.406259 17.989217 n.a. n.a. 0.987390998885 0.2081821 0.00202065712049 -0.4674919 127.2037 /T 52.7028 126.7/ 0.4006 n.a. n.a. 28.640925 24.606351 -33.75208 2024-Nov-30 20:00 02 39 16.29 -23 49 48.8 156.634361 18.795378 n.a. n.a. 0.987391831078 0.2067973 0.00201880305537 -0.4569619 127.2780 /T 52.6286 126.7/ 0.3921 n.a. n.a. 28.786201 23.945561 -33.04320 2024-Nov-30 20:10 02 39 24.69 -23 45 24.1 158.899026 19.539083 n.a. n.a. 0.987392657707 0.2054074 0.00201699173590 -0.4461811 127.3527 /T 52.5541 126.8/ 0.3837 n.a. n.a. 28.947061 23.330079 -32.29991 2024-Nov-30 20:20 02 39 32.94 -23 40 56.8 161.198535 20.218170 n.a. n.a. 0.987393478750 0.2040124 0.00201522412501 -0.4351711 127.4277 /T 52.4793 126.8/ 0.3754 n.a. n.a. 29.122593 22.761366 -31.52467 2024-Nov-30 20:30 02 39 41.04 -23 36 26.7 163.530805 20.830585 n.a. n.a. 0.987394294188 0.2026121 0.00201350109800 -0.4239539 127.5030 /T 52.4041 126.8/ 0.3672 n.a. n.a. 29.311882 22.240580 -30.72009 2024-Nov-30 20:40 02 39 49.02 -23 31 53.8 165.893389 21.374408 n.a. n.a. 0.987395103999 0.2012066 0.00201182344067 -0.4125521 127.5788 /T 52.3285 126.9/ 0.3592 n.a. n.a. 29.514019 21.768596 -29.88891 2024-Nov-30 20:50 02 39 56.90 -23 27 18.1 168.283489 21.847880 n.a. n.a. 0.987395908163 0.1997958 0.00201019184750 -0.4009887 127.6550 /T 52.2525 126.9/ 0.3512 n.a. n.a. 29.728115 21.346014 -29.03397 2024-Nov-30 21:00 02 40 04.69 -23 22 39.6 170.697973 22.249425 n.a. n.a. 0.987396706657 0.1983798 0.00200860692003 -0.3892870 127.7317 /T 52.1760 126.9/ 0.3433 n.a. n.a. 29.953307 20.973175 -28.15819 2024-Nov-30 21:10 02 40 12.41 -23 17 58.4 173.133404 22.577673 n.a. n.a. 0.987397499462 0.1969585 0.00200706916561 -0.3774706 127.8089 /T 52.0989 126.9/ 0.3356 n.a. n.a. 30.188760 20.650181 -27.26455 2024-Nov-30 21:20 02 40 20.08 -23 13 14.3 175.586078 22.831485 n.a. n.a. 0.987398286556 0.1955319 0.00200557899605 -0.3655636 127.8867 /T 52.0213 127.0/ 0.3281 n.a. n.a. 30.433680 20.376910 -26.35608 2024-Nov-30 21:30 02 40 27.73 -23 08 27.5 178.052071 23.009966 n.a. n.a. 0.987399067917 0.1940999 0.00200413672676 -0.3535901 127.9650 /T 51.9431 127.0/ 0.3206 n.a. n.a. 30.687313 20.153037 -25.43586 2024-Nov-30 21:40 t 02 40 35.35 -23 03 37.8 180.527287 23.112484 n.a. n.a. 0.987399843524 0.1926627 0.00200274257584 -0.3415743 128.0440 /T 51.8643 127.0/ 0.3134 n.a. n.a. 30.948953 19.978051 -24.50693 2024-Nov-30 21:50 e 02 40 42.99 -22 58 45.4 183.007517 23.138680 n.a. n.a. 0.987400613356 0.1912200 0.00200139666361 -0.3295408 128.1237 /T 51.7848 127.0/ 0.3062 n.a. n.a. 31.217941 19.851270 -23.57236 2024-Nov-30 22:00 02 40 50.64 -22 53 50.2 185.488506 23.088474 n.a. n.a. 0.987401377391 0.1897720 0.00200009901215 -0.3175140 128.2040 /T 51.7046 127.1/ 0.2993 n.a. n.a. 31.493670 19.771866 -22.63517 2024-Nov-30 22:10 02 40 58.34 -22 48 52.3 187.966011 22.962065 n.a. n.a. 0.987402135608 0.1883186 0.00199884954514 -0.3055185 128.2851 /T 51.6237 127.1/ 0.2925 n.a. n.a. 31.775582 19.738872 -21.69834 2024-Nov-30 22:20 02 41 06.10 -22 43 51.7 190.435867 22.759930 n.a. n.a. 0.987402887984 0.1868598 0.00199764808800 -0.2935788 128.3670 /T 51.5420 127.1/ 0.2859 n.a. n.a. 32.063172 19.751203 -20.76479 2024-Nov-30 22:30 02 41 13.94 -22 38 48.4 192.894046 22.482818 n.a. n.a. 0.987403634498 0.1853955 0.00199649436801 -0.2817193 128.4496 /T 51.4595 127.1/ 0.2795 n.a. n.a. 32.355986 19.807666 -19.83736 2024-Nov-30 22:40 02 41 21.88 -22 33 42.5 195.336718 22.131734 n.a. n.a. 0.987404375129 0.1839258 0.00199538801482 -0.2699642 128.5331 /T 51.3762 127.2/ 0.2732 n.a. n.a. 32.653619 19.906979 -18.91881 2024-Nov-30 22:50 02 41 29.93 -22 28 34.0 197.760296 21.707925 n.a. n.a. 0.987405109854 0.1824506 0.00199432856119 -0.2583376 128.6174 /T 51.2921 127.2/ 0.2672 n.a. n.a. 32.955714 20.047774 -18.01178 2024-Nov-30 23:00 02 41 38.11 -22 23 23.0 200.161481 21.212862 n.a. n.a. 0.987405838651 0.1809698 0.00199331544374 -0.2468634 128.7025 /T 51.2071 127.2/ 0.2613 n.a. n.a. 33.261957 20.228615 -17.11881 2024-Nov-30 23:10 02 41 46.44 -22 18 09.5 202.537297 20.648214 n.a. n.a. 0.987406561498 0.1794836 0.00199234800413 -0.2355651 128.7886 /T 51.1211 127.2/ 0.2556 n.a. n.a. 33.572080 20.448005 -16.24232 2024-Nov-30 23:20 02 41 54.95 -22 12 53.5 204.885117 20.015833 n.a. n.a. 0.987407278373 0.1779918 0.00199142549032 -0.2244658 128.8756 /T 51.0343 127.3/ 0.2502 n.a. n.a. 33.885851 20.704393 -15.38458 2024-Nov-30 23:30 02 42 03.63 -22 07 35.2 207.202678 19.317719 n.a. n.a. 0.987407989254 0.1764945 0.00199054705801 -0.2135884 128.9635 /T 50.9465 127.3/ 0.2450 n.a. n.a. 34.203074 20.996187 -14.54775 2024-Nov-30 23:40 02 42 12.52 -22 02 14.5 209.488088 18.556002 n.a. n.a. 0.987408694118 0.1749916 0.00198971177237 -0.2029551 129.0524 /T 50.8578 127.3/ 0.2399 n.a. n.a. 34.523585 21.321754 -13.73380 2024-Nov-30 23:50 02 42 21.62 -21 56 51.6 211.739830 17.732915 n.a. n.a. 0.987409392943 0.1734830 0.00198891860985 -0.1925880 129.1423 /T 50.7680 127.4/ 0.2351 n.a. n.a. 34.847250 21.679436 -12.94461 2024-Dec-01 00:00 02 42 30.95 -21 51 26.4 213.956755 16.850772 n.a. n.a. 0.987410085706 0.1719689 0.00198816646026 -0.1825083 129.2332 /T 50.6773 127.4/ 0.2305 n.a. n.a. 35.173954 22.067547 -12.18187 $$EOE *************************************************************************************************************************************************************************************************************************************************** Column meaning: TIME Times PRIOR to 1962 are UT1, a mean-solar time closely related to the prior but now-deprecated GMT. Times AFTER 1962 are in UTC, the current civil or "wall-clock" time-scale. UTC is kept within 0.9 seconds of UT1 using integer leap-seconds for 1972 and later years. Conversion from the internal Barycentric Dynamical Time (TDB) of solar system dynamics to the non-uniform civil UT time-scale requested for output has not been determined for UTC times after the next July or January 1st. Therefore, the last known leap-second is used as a constant over future intervals. Time tags refer to the UT time-scale conversion from TDB on Earth regardless of observer location within the solar system, although clock rates may differ due to the local gravity field and no analog to "UT" may be defined for that location. Any 'b' symbol in the 1st-column denotes a B.C. date. First-column blank (" ") denotes an A.D. date. CALENDAR SYSTEM Mixed calendar mode was active such that calendar dates after AD 1582-Oct-15 (if any) are in the modern Gregorian system. Dates prior to 1582-Oct-5 (if any) are in the Julian calendar system, which is automatically extended for dates prior to its adoption on 45-Jan-1 BC. The Julian calendar is useful for matching historical dates. The Gregorian calendar more accurately corresponds to the Earth's orbital motion and seasons. A "Gregorian-only" calendar mode is available if such physical events are the primary interest. NOTE: "n.a." in output means quantity "not available" at the print-time. SOLAR PRESENCE (OBSERVING SITE) Time tag is followed by a blank, then a solar-presence condition code: '*' Daylight (refracted solar upper-limb on or above apparent horizon) 'C' Civil twilight/dawn 'N' Nautical twilight/dawn 'A' Astronomical twilight/dawn ' ' Night OR geocentric ephemeris LUNAR PRESENCE WITH TARGET RISE/TRANSIT/SET EVENT MARKER (OBSERVING SITE) The solar-presence code column is immediately followed by another marker: 'm' Refracted upper-limb of Moon on or above apparent horizon ' ' Refracted upper-limb of Moon below apparent horizon OR geocentric The lunar presence marker (an ongoing state) can be over-ridden by a target event marker if an event has occurred since the last output step: 'r' Rise (target body on or went above cut-off RTS elevation) 'e' Elevation max (target body maximum elevation angle has occurred) 't' Transit (target body at or passed through observer meridian) 's' Set (target body on or went below cut-off RTS elevation) RTS MARKERS (TVH) Rise and set are with respect to the reference ellipsoid true visual horizon defined by the elevation cut-off angle. Horizon dip and yellow-light refraction (Earth only) are considered. Accuracy is < or = to twice the requested search step-size. 'R.A._____(ICRF)_____DEC' = Astrometric right ascension and declination of the target center with respect to the observing site (coordinate origin) in the reference frame of the planetary ephemeris (ICRF). Compensated for down-leg light-time delay aberration. Units: RA in hours-minutes-seconds of time, HH MM SS.ff{ffff} DEC in degrees-minutes-seconds of arc, sDD MN SC.f{ffff} 'Azi____(a-app)___Elev' = Airless apparent azimuth and elevation of target center. Compensated for light-time, the gravitational deflection of light, stellar aberration, precession and nutation. Azimuth is measured clockwise from north: North(0) -> East(90) -> South(180) -> West(270) -> North (360) Elevation angle is with respect to a plane perpendicular to the reference surface local zenith direction. TOPOCENTRIC ONLY. Units: DEGREES 'APmag S-brt' = The targets' approximate apparent visual magnitude and surface brightness. For planets and natural satellites, output is restricted to solar phase angles covered by observational data. Outside the observed phase angle range, "n.a." may be output to avoid extrapolation beyond the limit of model validity. For Earth-based observers, the estimated dimming due to atmospheric absorption (extinction) is available as a separate, requestable quantity. Surface brightness is the average airless visual magnitude of a square-arcsecond of the illuminated portion of the apparent disk. It is computed only if the target radius is known. Units: MAGNITUDES & MAGNITUDES PER SQUARE ARCSECOND 'r rdot' = The Sun's apparent range ("r", light-time aberrated) and range-rate ("rdot") relative to the target center, as seen by the observer. A positive "rdot" means the target center was moving away from the Sun, negative means moving toward the Sun. Units: AU and KM/S 'delta deldot' = Apparent range ("delta", light-time aberrated) and range-rate ("delta-dot") of the target center relative to the observer. A positive "deldot" means the target center is moving away from the observer, negative indicates movement toward the observer. Units: AU and KM/S 'S-O-T /r' = Sun-Observer-Target apparent SOLAR ELONGATION ANGLE seen from the observers' location at print-time. The '/r' column provides a code indicating the targets' apparent position relative to the Sun in the observers' sky, as described below: Case A: For an observing location on the surface of a rotating body, that body rotational sense is considered: /T indicates target TRAILS Sun (evening sky: rises and sets AFTER Sun) /L indicates target LEADS Sun (morning sky: rises and sets BEFORE Sun) Case B: For an observing point that does not have a rotational model (such as a spacecraft), the "leading" and "trailing" condition is defined by the observers' heliocentric ORBITAL motion: * If continuing in the observers' current direction of heliocentric motion would encounter the targets' apparent longitude first, followed by the Sun's, the target LEADS the Sun as seen by the observer. * If the Sun's apparent longitude would be encountered first, followed by the targets', the target TRAILS the Sun. Two other codes can be output: /* indicates observer is Sun-centered (undefined) /? Target is aligned with Sun center (no lead or trail) The S-O-T solar elongation angle is numerically the minimum separation angle of the Sun and target in the sky in any direction. It does NOT indicate the amount of separation in the leading or trailing directions, which would be defined along the equator of a spherical coordinate system. Units: DEGREES 'S-T-O' = The Sun-Target-Observer angle; the interior vertex angle at target center formed by a vector from the target to the apparent center of the Sun (at reflection time on the target) and the apparent vector from target to the observer at print-time. Slightly different from true PHASE ANGLE (requestable separately) at the few arcsecond level in that it includes stellar aberration on the down-leg from target to observer. Units: DEGREES 'T-O-M/MN_Illu%' = Target-Observer-Moon LUNAR ELONGATION angle and illuminated percentage. The apparent lunar elongation angle between target body center and Moon center, seen from the observing site, along with fraction of the lunar disk illuminated by the Sun. A negative lunar elongation angle indicates the target center is behind the Moon. Units: DEGREES & PERCENT 'RA_3sigma DEC_3sigma' = Uncertainty in Right-Ascension and Declination. Output values are the formal +/- 3 standard-deviations (sigmas) around nominal position. Units: ARCSECONDS 'Sky_motion Sky_mot_PA RelVel-ANG' = Total apparent angular rate of the target in the plane-of-sky. "Sky_mot_PA" is the position angle of the target's direction of motion in the plane-of-sky, measured counter-clockwise from the apparent of-date north pole direction. "RelVel-ANG" is the flight path angle of the target's relative motion with respect to the observer's line-of-sight, in the range [-90,+90], where positive values indicate motion away from the observer, negative values are toward the observer: -90 = target is moving directly toward the observer 0 = target is moving at right angles to the observer's line-of-sight +90 = target is moving directly away from the observer UNITS: ARCSECONDS/MINUTE, DEGREES, DEGREES Computations by ... Solar System Dynamics Group, Horizons On-Line Ephemeris System 4800 Oak Grove Drive, Jet Propulsion Laboratory Pasadena, CA 91109 USA General site: https://ssd.jpl.nasa.gov/ Mailing list: https://ssd.jpl.nasa.gov/email_list.html System news : https://ssd.jpl.nasa.gov/horizons/news.html User Guide : https://ssd.jpl.nasa.gov/horizons/manual.html Connect : browser https://ssd.jpl.nasa.gov/horizons/app.html#/x API https://ssd-api.jpl.nasa.gov/doc/horizons.html command-line telnet ssd.jpl.nasa.gov 6775 e-mail/batch https://ssd.jpl.nasa.gov/ftp/ssd/hrzn_batch.txt scripts https://ssd.jpl.nasa.gov/ftp/ssd/SCRIPTS Author : Jon.D.Giorgini@jpl.nasa.gov ***************************************************************************************************************************************************************************************************************************************************