API VERSION: 1.2 API SOURCE: NASA/JPL Horizons API ******************************************************************************* Revised: Oct 31, 2024 Europa Clipper (Spacecraft) / (Sun, Jupiter) -159 https://science.nasa.gov/mission/europa-clipper/ https://europa.nasa.gov/ BACKGROUND: NASA's Europa Clipper spacecraft will carry a suite of science instruments to assess habitability of Jupiter's ice-covered moon Europa (502) while confirming the existence and nature of an expected sub-surface ocean. Launched : 2024-Oct-14 16:06 UTC (SpaceX Falcon Heavy, KSC LC-39A) Mars gravity assist : 2025-Mar-01 Earth gravity assist: 2026-Dec-03 Arrival : 2030-Apr-11 (5.50 year time-of-flight) Mission length : 4.12 years (prime mission, JOI to E49) End-of-mission : 2034-Sep (directed to Ganymede impact ~30d after E49) The spacecraft is expected to orbit Jupiter 75 times and conduct 49 flybys of Europa at altitudes as low as 25 km. This will reduce exposure to the high levels of radiation Europa moves within. Gravity-assists from Europa (49), Ganymede (7), and Callisto (9) will be used to target different Europa close approach points on each flyby. SPACECRAFT: Considering solar arrays and radar antennas, Europa Clipper will be the largest spacecraft NASA has developed to-date for an interplanetary mission. When arrays are deployed, the spacecraft will span 30.5 meters. Main body (bus): 3 x 4.7 x 4 meters Dry mass (no propellant): 3241 kg Propellant: 2750 kg Solar power arrays: 2 x 14.2 x 4.1 meters SCIENCE INSTRUMENTS Europa Imaging System (EIS) Europa Thermal Emission Imaging System (E-THEMIS) Europa Ultraviolet Spectrograph (Europa-UVS) Mapping Imaging Spectrometer for Europa (MISE) Europa Clipper Magnetometer (ECM) Plasma Instrument for Magnetic Sounding (PIMS) Gravity/Radio Science Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) MAss Spectrometer for Planetary EXploration/Europa (MASPEX) SUrface Dust Analyzer (SUDA) SPACECRAFT TRAJECTORY (from JPL navigation): Segments marked by '*' below are pre-launch predictions. Based on tracking data through 2024-Oct-30, data thereafter is predicted: Trajectory files (JPL mission design/nav) Start End --------------------------------------------------- ----------- ----------- *21F31_MEGA_L241014_A300411_LP05_V7 (16:13 - 17:08) 2024-Oct-14 2024-Oct-14 trj_241014-241103-dco2410142047-postLaunch-OD001-v1 2024-Oct-14 2024-Oct-18 trj_241018-250101-dco2410291636-OD016-v1_wfimp 2024-Oct-18 2025-Jan-01 *21F31_MEGA_L241014_A300411_LP05_V7 2025-Jan-01 2031-Feb-07 ******************************************************************************* ******************************************************************************* Ephemeris / API_USER Mon Nov 4 02:41:03 2024 Pasadena, USA / Horizons ******************************************************************************* Target body name: Europa Clipper (spacecraft) (-159) {source: Europa_Clipper_merged} Center body name: Earth (399) {source: Europa_Clipper_merged} Center-site name: iTelescope Obs.,Beryl Junc. (Sato) ******************************************************************************* Start time : A.D. 2024-Oct-31 00:00:00.0000 UT Stop time : A.D. 2024-Nov-01 00:00:00.0000 UT Step-size : 10 minutes ******************************************************************************* Target pole/equ : undefined Target radii : undefined Center geodetic : 246.3025, 37.7377919, 1.56349 {E-lon(deg),Lat(deg),Alt(km)} Center cylindric: 246.3025,5051.53114,3883.42609 {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: Europa_Clipper_merge Rel. light bend : Sun {source: Europa_Clipper_merge 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.241101.p250128 EOP coverage : DATA-BASED 1962-JAN-20 TO 2024-NOV-01. PREDICTS-> 2025-JAN-27 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 >..... Elevation Cut-off Requested .....< 2024-Oct-31 05:50 08 35 56.69 +30 25 10.1 51.157547 0.851333 n.a. n.a. 0.999108708177 2.1582975 0.06039667879993 5.8155489 94.2596 /L 82.2854 80.9/ 1.5226 n.a. n.a. 0.3177803 39.470720 87.715501 2024-Oct-31 06:00 08 35 56.84 +30 25 12.6 52.656305 2.411652 n.a. n.a. 0.999117367648 2.1599144 0.06041998869148 5.8096160 94.2661 /L 82.2776 81.0/ 1.5008 n.a. n.a. 0.3087971 36.028310 87.776893 2024-Oct-31 06:10 08 35 56.97 +30 25 15.1 54.123673 4.003131 n.a. n.a. 0.999126033604 2.1615313 0.06044327590941 5.8042429 94.2727 /L 82.2698 81.2/ 1.4792 n.a. n.a. 0.3004207 32.382929 87.834305 2024-Oct-31 06:20 08 35 57.09 +30 25 17.7 55.561185 5.624096 n.a. n.a. 0.999134706045 2.1631481 0.06046654271854 5.7994393 94.2794 /L 82.2619 81.3/ 1.4577 n.a. n.a. 0.2927725 28.534010 87.886831 2024-Oct-31 06:30 08 35 57.19 +30 25 20.3 56.970419 7.272948 n.a. n.a. 0.999143384971 2.1647649 0.06048979142107 5.7952142 94.2861 /L 82.2539 81.4/ 1.4363 n.a. n.a. 0.2859742 24.486741 87.933559 2024-Oct-31 06:40 08 35 57.27 +30 25 22.9 58.352987 8.948164 n.a. n.a. 0.999152070381 2.1663815 0.06051302435241 5.7915751 94.2928 /L 82.2459 81.5/ 1.4151 n.a. n.a. 0.2801441 20.253277 87.973603 2024-Oct-31 06:50 08 35 57.34 +30 25 25.6 59.710533 10.648291 n.a. n.a. 0.999160762274 2.1679981 0.06053624387663 5.7885288 94.2996 /L 82.2378 81.6/ 1.3940 n.a. n.a. 0.2753920 15.853628 88.006137 2024-Oct-31 07:00 08 35 57.39 +30 25 28.2 61.044729 12.371943 n.a. n.a. 0.999169460652 2.1696147 0.06055945238192 5.7860806 94.3065 /L 82.2296 81.7/ 1.3731 n.a. n.a. 0.2718143 11.315960 88.030434 2024-Oct-31 07:10 08 35 57.42 +30 25 30.9 62.357277 14.117804 n.a. n.a. 0.999178165512 2.1712311 0.06058265227605 5.7842348 94.3135 /L 82.2214 81.8/ 1.3524 n.a. n.a. 0.2694878 6.6760903 88.045908 2024-Oct-31 07:20 08 35 57.44 +30 25 33.6 63.649909 15.884616 n.a. n.a. 0.999186876856 2.1728475 0.06060584598176 5.7829947 94.3205 /L 82.2131 81.9/ 1.3319 n.a. n.a. 0.2684654 1.9760320 88.052153 2024-Oct-31 07:30 08 35 57.43 +30 25 36.2 64.924391 17.671181 n.a. n.a. 0.999195594682 2.1744638 0.06062903593214 5.7823622 94.3275 /L 82.2048 82.0/ 1.3116 n.a. n.a. 0.2687722 357.26168 88.048971 2024-Oct-31 07:40 08 35 57.42 +30 25 38.9 66.182529 19.476357 n.a. n.a. 0.999204318990 2.1760800 0.06065222456595 5.7823381 94.3347 /L 82.1964 82.1/ 1.2915 n.a. n.a. 0.2704033 352.57988 88.036381 2024-Oct-31 07:50 08 35 57.38 +30 25 41.6 67.426176 21.299053 n.a. n.a. 0.999213049781 2.1776961 0.06067541432291 5.7829221 94.3418 /L 82.1880 82.2/ 1.2716 n.a. n.a. 0.2733249 347.97541 88.014624 2024-Oct-31 08:00 08 35 57.33 +30 25 44.3 68.657242 23.138225 n.a. n.a. 0.999221787053 2.1793122 0.06069860763918 5.7841128 94.3491 /L 82.1795 82.3/ 1.2519 n.a. n.a. 0.2774763 343.48817 87.984139 2024-Oct-31 08:10 08 35 57.26 +30 25 46.9 69.877706 24.992875 n.a. n.a. 0.999230530806 2.1809282 0.06072180694254 5.7859075 94.3564 /L 82.1709 82.4/ 1.2325 n.a. n.a. 0.2827742 339.15124 87.945534 2024-Oct-31 08:20 08 35 57.17 +30 25 49.6 71.089632 26.862043 n.a. n.a. 0.999239281041 2.1825441 0.06074501464779 5.7883022 94.3637 /L 82.1623 82.5/ 1.2133 n.a. n.a. 0.2891182 334.98974 87.899551 2024-Oct-31 08:30 08 35 57.07 +30 25 52.2 72.295190 28.744806 n.a. n.a. 0.999248037756 2.1841600 0.06076823315211 5.7912922 94.3711 /L 82.1536 82.6/ 1.1944 n.a. n.a. 0.2963958 331.02067 87.847017 2024-Oct-31 08:40 08 35 56.95 +30 25 54.7 73.496674 30.640274 n.a. n.a. 0.999256800952 2.1857758 0.06079146483056 5.7948713 94.3786 /L 82.1449 82.8/ 1.1757 n.a. n.a. 0.3044881 327.25347 87.788813 2024-Oct-31 08:50 08 35 56.81 +30 25 57.3 74.696535 32.547583 n.a. n.a. 0.999265570627 2.1873915 0.06081471203138 5.7990322 94.3861 /L 82.1361 82.9/ 1.1573 n.a. n.a. 0.3132740 323.69103 87.725838 2024-Oct-31 09:00 08 35 56.66 +30 25 59.8 75.897412 34.465893 n.a. n.a. 0.999274346783 2.1890071 0.06083797707163 5.8037666 94.3937 /L 82.1272 83.0/ 1.1391 n.a. n.a. 0.3226339 320.33098 87.658980 2024-Oct-31 09:10 08 35 56.49 +30 26 02.2 77.102173 36.394381 n.a. n.a. 0.999283129418 2.1906227 0.06086126223259 5.8090651 94.4013 /L 82.1183 83.1/ 1.1213 n.a. n.a. 0.3324520 317.16698 87.589099 2024-Oct-31 09:20 08 35 56.31 +30 26 04.6 78.313969 38.332238 n.a. n.a. 0.999291918532 2.1922381 0.06088456975554 5.8149171 94.4090 /L 82.1094 83.2/ 1.1037 n.a. n.a. 0.3426183 314.18994 87.517014 2024-Oct-31 09:30 08 35 56.11 +30 26 07.0 79.536294 40.278659 n.a. n.a. 0.999300714125 2.1938535 0.06090790183737 5.8213110 94.4167 /L 82.1004 83.3/ 1.0864 n.a. n.a. 0.3530293 311.38896 87.443492 2024-Oct-31 09:40 08 35 55.90 +30 26 09.3 80.773064 42.232840 n.a. n.a. 0.999309516196 2.1954689 0.06093126062636 5.8282342 94.4245 /L 82.0914 83.4/ 1.0693 n.a. n.a. 0.3635887 308.75219 87.369246 2024-Oct-31 09:50 08 35 55.67 +30 26 11.5 82.028718 44.193967 n.a. n.a. 0.999318324746 2.1970841 0.06095464821814 5.8356731 94.4323 /L 82.0823 83.5/ 1.0526 n.a. n.a. 0.3742075 306.26742 87.294936 2024-Oct-31 10:00 08 35 55.43 +30 26 13.7 83.308336 46.161206 n.a. n.a. 0.999327139773 2.1986993 0.06097806665152 5.8436130 94.4402 /L 82.0732 83.6/ 1.0362 n.a. n.a. 0.3848037 303.92249 87.221165 2024-Oct-31 10:10 08 35 55.18 +30 26 15.8 84.617807 48.133690 n.a. n.a. 0.999335961278 2.2003144 0.06100151790475 5.8520383 94.4481 /L 82.0640 83.7/ 1.0200 n.a. n.a. 0.3953019 301.70563 87.148485 2024-Oct-31 10:20 08 35 54.91 +30 26 17.8 85.964026 50.110508 n.a. n.a. 0.999344789261 2.2019294 0.06102500389161 5.8609324 94.4560 /L 82.0548 83.8/ 1.0042 n.a. n.a. 0.4056332 299.60561 87.077398 2024-Oct-31 10:30 08 35 54.63 +30 26 19.8 87.355165 52.090680 n.a. n.a. 0.999353623720 2.2035444 0.06104852645772 5.8702780 94.4640 /L 82.0455 83.9/ 0.9886 n.a. n.a. 0.4157343 297.61186 87.008359 2024-Oct-31 10:40 08 35 54.34 +30 26 21.7 88.801025 54.073134 n.a. n.a. 0.999362464656 2.2051593 0.06107208737704 5.8800567 94.4720 /L 82.0363 84.0/ 0.9734 n.a. n.a. 0.4255475 295.71453 86.941781 2024-Oct-31 10:50 08 35 54.04 +30 26 23.5 90.313511 56.056671 n.a. n.a. 0.999371312068 2.2067741 0.06109568834848 5.8902494 94.4800 /L 82.0269 84.1/ 0.9584 n.a. n.a. 0.4350202 293.90448 86.878034 2024-Oct-31 11:00 08 35 53.73 +30 26 25.2 91.907266 58.039922 n.a. n.a. 0.999380165956 2.2083888 0.06111933099259 5.9008362 94.4881 /L 82.0176 84.2/ 0.9438 n.a. n.a. 0.4441041 292.17328 86.817453 2024-Oct-31 11:10 08 35 53.40 +30 26 26.8 93.600555 60.021281 n.a. n.a. 0.999389026320 2.2100034 0.06114301684847 5.9117964 94.4962 /L 82.0082 84.3/ 0.9295 n.a. n.a. 0.4527555 290.51315 86.760336 2024-Oct-31 11:20 08 35 53.07 +30 26 28.3 95.416483 61.998821 n.a. n.a. 0.999397893159 2.2116180 0.06116674737078 5.9231086 94.5043 /L 81.9988 84.4/ 0.9155 n.a. n.a. 0.4609344 288.91694 86.706951 2024-Oct-31 11:30 08 35 52.73 +30 26 29.8 97.384740 63.970166 n.a. n.a. 0.999406766473 2.2132325 0.06119052392697 5.9347506 94.5124 /L 81.9894 84.5/ 0.9018 n.a. n.a. 0.4686047 287.37806 86.657533 2024-Oct-31 11:40 08 35 52.38 +30 26 31.1 99.544096 65.932305 n.a. n.a. 0.999415646262 2.2148469 0.06121434779468 5.9466998 94.5206 /L 81.9799 84.5/ 0.8884 n.a. n.a. 0.4757335 285.89045 86.612289 2024-Oct-31 11:50 08 35 52.02 +30 26 32.4 101.946075 67.881319 n.a. n.a. 0.999424532526 2.2164613 0.06123822015918 5.9589329 94.5288 /L 81.9705 84.6/ 0.8752 n.a. n.a. 0.4822915 284.44849 86.571400 2024-Oct-31 12:00 08 35 51.65 +30 26 33.5 104.660421 69.811950 n.a. n.a. 0.999433425263 2.2180756 0.06126214211122 5.9714260 94.5369 /L 81.9610 84.7/ 0.8624 n.a. n.a. 0.4882522 283.04698 86.535023 2024-Oct-31 12:10 08 35 51.28 +30 26 34.5 107.783358 71.716936 n.a. n.a. 0.999442324474 2.2196898 0.06128611464482 5.9841547 94.5452 /L 81.9515 84.8/ 0.8500 n.a. n.a. 0.4935921 281.68110 86.503289 2024-Oct-31 12:20 08 35 50.91 +30 26 35.5 111.450141 73.585923 n.a. n.a. 0.999451230159 2.2213039 0.06131013865544 5.9970943 94.5534 /L 81.9420 84.9/ 0.8378 n.a. n.a. 0.4982905 280.34631 86.476308 2024-Oct-31 12:30 08 35 50.53 +30 26 36.3 115.854001 75.403677 n.a. n.a. 0.999460142317 2.2229179 0.06133421493817 6.0102196 94.5616 /L 81.9324 85.0/ 0.8258 n.a. n.a. 0.5023295 279.03838 86.454168 2024-Oct-31 12:40 A 08 35 50.14 +30 26 37.0 121.273380 77.147071 n.a. n.a. 0.999469060948 2.2245319 0.06135834418633 6.0235048 94.5698 /L 81.9229 85.1/ 0.8142 n.a. n.a. 0.5056937 277.75330 86.436938 2024-Oct-31 12:50 A 08 35 49.75 +30 26 37.7 128.105438 78.780065 n.a. n.a. 0.999477986051 2.2261458 0.06138252699001 6.0369243 94.5781 /L 81.9133 85.2/ 0.8029 n.a. n.a. 0.5083702 276.48725 86.424665 2024-Oct-31 13:00 A 08 35 49.36 +30 26 38.2 136.885261 80.245807 n.a. n.a. 0.999486917627 2.2277596 0.06140676383500 6.0504518 94.5863 /L 81.9038 85.3/ 0.7919 n.a. n.a. 0.5103487 275.23657 86.417380 2024-Oct-31 13:10 Nm 08 35 48.96 +30 26 38.6 148.211686 81.456664 n.a. n.a. 0.999495855674 2.2293733 0.06143105510180 6.0640611 94.5945 /L 81.8943 85.3/ 0.7811 n.a. n.a. 0.5116212 273.99775 86.415096 2024-Oct-31 13:20 Nm 08 35 48.57 +30 26 38.9 162.395654 82.290695 n.a. n.a. 0.999504800193 2.2309870 0.06145540106495 6.0777255 94.6027 /L 81.8847 85.4/ 0.7707 n.a. n.a. 0.5121822 272.76733 86.417807 2024-Oct-31 13:30 Nm 08 35 48.17 +30 26 39.0 178.747481 82.618479 n.a. n.a. 0.999513751184 2.2326006 0.06147980189248 6.0914185 94.6109 /L 81.8752 85.5/ 0.7605 n.a. n.a. 0.5120285 271.54196 86.425494 2024-Oct-31 13:40 Ct 08 35 47.78 +30 26 39.1 195.274937 82.374254 n.a. n.a. 0.999522708645 2.2342141 0.06150425764559 6.1051134 94.6191 /L 81.8657 85.6/ 0.7506 n.a. n.a. 0.5111590 270.31829 86.438120 2024-Oct-31 13:50 Cm 08 35 47.38 +30 26 39.1 209.859218 81.607945 n.a. n.a. 0.999531672578 2.2358276 0.06152876827854 6.1187836 94.6273 /L 81.8561 85.7/ 0.7409 n.a. n.a. 0.5095754 269.09297 86.455631 >..... Daylight Cut-off Requested .....< >..... Elevation Cut-off Requested .....< $$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 ***************************************************************************************************************************************************************************************************************************************************