******************************************************************************* JPL/HORIZONS Lemmon (C/2021 T4) 2025-Dec-12 18:02:55 Rec #:90004719 (+COV) Soln.date: 2025-Apr-14_09:29:19 # obs: 1259 (2021-2025) IAU76/J2000 helio. ecliptic osc. elements (au, days, deg., period=Julian yrs): EPOCH= 2460048.5 ! 2023-Apr-14.0000000 (TDB) RMSW= n.a. EC= .9999181935018592 QR= 1.483297977245064 TP= 2460157.0270268307 OM= 257.8823122014759 W= 329.8139299963154 IN= 160.777408841796 A= 18131.78672789139 MA= 359.9999561892108 ADIST= 36262.09015780554 PER= 2441569.5803825 N= 4.04E-7 ANGMOM= .029627961 DAN= 1.59118 DDN= 21.86478 L= 286.6604281 B= -9.528872099999999 MOID= .49752799 TP= 2023-Jul-31.5270268307 Comet physical (GM= km^3/s^2; RAD= km): GM= n.a. RAD= n.a. M1= 12.4 M2= n.a. k1= 4.5 k2= n.a. PHCOF= n.a. Comet non-gravitational force model (AMRAT=m^2/kg;A1-A3=au/d^2;DT=days;R0=au): AMRAT= 0. DT= 0. A1= 9.208681583405E-9 A2= -3.958460986614E-9 A3= 0. Standard model: ALN= .1112620426 NK= 4.6142 NM= 2.15 NN= 5.093 R0= 2.808 COMET comments 1: soln ref.= JPL#98, data arc: 2021-08-07 to 2025-03-24 2: k1=4.5; ******************************************************************************* ******************************************************************************* Ephemeris / WWW_USER Fri Dec 12 18:02:55 2025 Pasadena, USA / Horizons ******************************************************************************* Target body name: Lemmon (C/2021 T4) {source: JPL#98} Center body name: Earth (399) {source: DE441} Center-site name: GEOCENTRIC ******************************************************************************* Start time : A.D. 2023-Jul-20 00:00:00.0000 UT Stop time : A.D. 2023-Jul-21 00:00:00.0000 UT Step-size : 60 minutes ******************************************************************************* Target pole/equ : undefined Target radii : undefined Center geodetic : 0.0, 0.0, -6378.137 {E-lon(deg),Lat(deg),Alt(km)} Center cylindric: 0.0, 0.0, 0.0 {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 : Sun Vis. interferer : MOON (R_eq= 1737.400) km {source: DE441} Rel. light bend : Sun {source: DE441} Rel. lght bnd GM: 1.3271E+11 km^3/s^2 Small-body perts: Yes {source: SB441-N16} Atmos refraction: NO (AIRLESS) RA format : HMS Time format : CAL Calendar mode : Mixed Julian/Gregorian EOP file : eop.251212.p260310 EOP coverage : DATA-BASED 1962-JAN-20 TO 2025-DEC-12. PREDICTS-> 2026-MAR-09 Units conversion: 1 au= 149597870.700 km, c= 299792.458 km/s, 1 day= 86400.0 s Table cut-offs 1: Elevation (-90.0deg=NO ),Airmass (>38.000=NO), Daylight (NO ) Table cut-offs 2: Solar elongation ( 0.0,180.0=NO ),Local Hour Angle( 0.0=NO ) Table cut-offs 3: RA/DEC angular rate ( 0.0=NO ) ******************************************************************************* Initial IAU76/J2000 heliocentric ecliptic osculating elements (au, days, deg.): EPOCH= 2460048.5 ! 2023-Apr-14.0000000 (TDB) RMSW= n.a. EC= .9999181935018592 QR= 1.483297977245064 TP= 2460157.0270268307 OM= 257.8823122014759 W= 329.8139299963154 IN= 160.777408841796 Equivalent ICRF heliocentric cartesian coordinates (au, au/d): X= 1.968197185783401E+00 Y= 7.785134019091711E-02 Z=-7.145498016163827E-01 VX=-1.020770758015099E-02 VY=-1.303107474548769E-02 VZ=-2.902693214611334E-03 Comet physical (GM= km^3/s^2; RAD= km): GM= n.a. RAD= n.a. M1= 12.4 M2= n.a. k1= 4.5 k2= n.a. PHCOF= n.a. Comet non-gravitational force model (AMRAT=m^2/kg;A1-A3=au/d^2;DT=days;R0=au): AMRAT= 0. DT= 0. A1= 9.208681583405E-9 A2= -3.958460986614E-9 A3= 0. Standard model: ALN= .1112620426 NK= 4.6142 NM= 2.15 NN= 5.093 R0= 2.808 ************************************************************************************************************************** Date__(UT)__HR:MN r rdot delta deldot S-O-T /r Cnst RNG_3sigma RNGRT_3sig ************************************************************************************************************************** $$SOE 2023-Jul-20 00:00 1.492179890031 -2.6649116 0.54164199317149 -2.3759343 144.8798 /L Tel 1146.6915 0.0001264 2023-Jul-20 01:00 1.492115873705 -2.6554396 0.54158704611377 -2.1906365 144.8770 /L Tel 1143.2872 0.0001264 2023-Jul-20 02:00 1.492052085377 -2.6459661 0.54153655885107 -2.0052885 144.8732 /L Tel 1139.8918 0.0001265 2023-Jul-20 03:00 1.491988525085 -2.6364909 0.54149053253009 -1.8198951 144.8683 /L Tel 1136.5056 0.0001266 2023-Jul-20 04:00 1.491925192869 -2.6270142 0.54144896818244 -1.6344612 144.8624 /L Tel 1133.1289 0.0001267 2023-Jul-20 05:00 1.491862088766 -2.6175358 0.54141186672454 -1.4489915 144.8554 /L Tel 1129.7618 0.0001267 2023-Jul-20 06:00 1.491799212815 -2.6080558 0.54137922895743 -1.2634907 144.8474 /L Tel 1126.4048 0.0001268 2023-Jul-20 07:00 1.491736565054 -2.5985742 0.54135105556675 -1.0779638 144.8383 /L Tel 1123.0580 0.0001269 2023-Jul-20 08:00 1.491674145522 -2.5890911 0.54132734712259 -0.8924155 144.8282 /L Tel 1119.7216 0.0001270 2023-Jul-20 09:00 1.491611954255 -2.5796063 0.54130810407942 -0.7068505 144.8170 /L Tel 1116.3960 0.0001270 2023-Jul-20 10:00 1.491549991292 -2.5701200 0.54129332677608 -0.5212738 144.8048 /L Tel 1113.0814 0.0001271 2023-Jul-20 11:00 1.491488256670 -2.5606321 0.54128301543565 -0.3356902 144.7916 /L Tel 1109.7780 0.0001272 2023-Jul-20 12:00 1.491426750428 -2.5511427 0.54127717016550 -0.1501043 144.7774 /L Tel 1106.4862 0.0001273 2023-Jul-20 13:00 1.491365472601 -2.5416516 0.54127579095721 0.0354789 144.7621 /L Tel 1103.2061 0.0001273 2023-Jul-20 14:00 1.491304423228 -2.5321590 0.54127887768660 0.2210546 144.7457 /L Tel 1099.9381 0.0001274 2023-Jul-20 15:00 1.491243602345 -2.5226649 0.54128643011373 0.4066181 144.7283 /T Tel 1096.6823 0.0001275 2023-Jul-20 16:00 1.491183009990 -2.5131692 0.54129844788292 0.5921645 144.7100 /T Tel 1093.4392 0.0001276 2023-Jul-20 17:00 1.491122646199 -2.5036720 0.54131493052280 0.7776890 144.6905 /T Tel 1090.2088 0.0001276 2023-Jul-20 18:00 1.491062511009 -2.4941733 0.54133587744636 0.9631868 144.6701 /T Tel 1086.9915 0.0001277 2023-Jul-20 19:00 1.491002604457 -2.4846730 0.54136128795100 1.1486531 144.6486 /T Tel 1083.7875 0.0001278 2023-Jul-20 20:00 1.490942926578 -2.4751712 0.54139116121864 1.3340832 144.6261 /T Tel 1080.5972 0.0001278 2023-Jul-20 21:00 1.490883477410 -2.4656679 0.54142549631580 1.5194721 144.6026 /T Tel 1077.4207 0.0001279 2023-Jul-20 22:00 1.490824256988 -2.4561631 0.54146429219372 1.7048152 144.5780 /T Tel 1074.2583 0.0001280 2023-Jul-20 23:00 1.490765265348 -2.4466568 0.54150754768846 1.8901077 144.5525 /T Tel 1071.1103 0.0001280 2023-Jul-21 00:00 1.490706502527 -2.4371489 0.54155526152108 2.0753447 144.5259 /T Tel 1067.9769 0.0001281 $$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. STATISTICAL UNCERTAINTIES Output includes formal +/- 3 standard-deviation statistical orbit uncertainty quantities. There is a 99.7% (1-D) or 98.9% (2-D) chance the actual value is within given bounds. These statistical calculations assume observational data errors are random. If there are systematic biases (such as timing, reduction or star-catalog errors), results can be optimistic. Because the epoch covariance is mapped using linearized variational partial derivatives, results can also be optimistic for times far from the solution epoch, particularly for objects having close planetary encounters. '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 'Cnst' = Constellation ID; the 3-letter abbreviation for the name of the constellation containing the target centers' astrometric position, as defined by IAU (1930) boundary delineation. See documentation for list of abbreviations. 'RNG_3sigma RNGRT_3sig' = Range and range rate (radial velocity) formal 3-standard-deviation uncertainties. Units: KM, KM/S 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/horizons_batch.txt scripts https://ssd.jpl.nasa.gov/ftp/ssd/SCRIPTS Author : Jon.D.Giorgini@jpl.nasa.gov ************************************************************************************************************************** !$$SOF COMMAND = '2021 T4' QUANTITIES = '19,20,23,29,39' START_TIME = '2023-07-20' STEP_SIZE = '1 hour' STOP_TIME = '2023-07-21'