API VERSION: 1.2 API SOURCE: NASA/JPL Horizons API ******************************************************************************* Revised: Mar 13, 2025 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 2025-Mar-10. 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_241018-250130-dco2411082133-cru002-fin-OD018-v14 2024-Oct-18 2024-Nov-23 trj_241123-250315-dco2412031638-cru003-fin-OD020-v1 2024-Nov-23 2024-Dec-04 trj_241204-250311-dco2501221611-MGATRGa-OD034-v1 2024-Dec-04 2025-Jan-04 trj_250104-250614-dco2502250958-cru005-fin-OD042-v1 2025-Jan-04 2025-Feb-15 trj_250215-250614-dco2503101633-MGACU1-FIN-OD046-v1 2025-Feb-15 2025-Jun-14 *21F31_MEGA_L241014_A300411_LP05_V7 2025-Jun-14 2031-Feb-07 ******************************************************************************* ******************************************************************************* Ephemeris / API_USER Fri Apr 18 18:18:25 2025 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.250418.p250715 EOP coverage : DATA-BASED 1962-JAN-20 TO 2025-APR-18. PREDICTS-> 2025-JUL-14 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 51.157548 0.851332 n.a. n.a. 0.999108707537 2.1582974 0.06039667905528 5.8155494 94.2596 /L 82.2854 80.9/ 1.5226 n.a. n.a. 0.3177800 39.470753 87.715503 2024-Oct-31 06:00 08 35 56.84 +30 25 12.6 52.656306 2.411651 n.a. n.a. 0.999117367008 2.1599144 0.06041998894890 5.8096166 94.2661 /L 82.2776 81.0/ 1.5008 n.a. n.a. 0.3087968 36.028340 87.776896 2024-Oct-31 06:10 08 35 56.97 +30 25 15.1 54.123674 4.003130 n.a. n.a. 0.999126032965 2.1615313 0.06044327616883 5.8042434 94.2727 /L 82.2698 81.2/ 1.4792 n.a. n.a. 0.3004204 32.382955 87.834308 2024-Oct-31 06:20 08 35 57.09 +30 25 17.7 55.561186 5.624095 n.a. n.a. 0.999134705406 2.1631481 0.06046654297994 5.7994398 94.2794 /L 82.2619 81.3/ 1.4577 n.a. n.a. 0.2927721 28.534032 87.886833 2024-Oct-31 06:30 08 35 57.19 +30 25 20.3 56.970420 7.272947 n.a. n.a. 0.999143384331 2.1647649 0.06048979168435 5.7952146 94.2861 /L 82.2539 81.4/ 1.4363 n.a. n.a. 0.2859738 24.486759 87.933562 2024-Oct-31 06:40 08 35 57.27 +30 25 22.9 58.352988 8.948163 n.a. n.a. 0.999152069741 2.1663815 0.06051302461777 5.7915756 94.2928 /L 82.2459 81.5/ 1.4151 n.a. n.a. 0.2801437 20.253292 87.973606 2024-Oct-31 06:50 08 35 57.34 +30 25 25.5 59.710534 10.648289 n.a. n.a. 0.999160761635 2.1679981 0.06053624414410 5.7885293 94.2996 /L 82.2378 81.6/ 1.3940 n.a. n.a. 0.2753917 15.853637 88.006140 2024-Oct-31 07:00 08 35 57.39 +30 25 28.2 61.044730 12.371942 n.a. n.a. 0.999169460012 2.1696147 0.06055945265142 5.7860811 94.3065 /L 82.2296 81.7/ 1.3731 n.a. n.a. 0.2718139 11.315963 88.030436 2024-Oct-31 07:10 08 35 57.42 +30 25 30.9 62.357278 14.117803 n.a. n.a. 0.999178164873 2.1712311 0.06058265254752 5.7842353 94.3135 /L 82.2214 81.8/ 1.3524 n.a. n.a. 0.2694875 6.6760871 88.045911 2024-Oct-31 07:20 08 35 57.44 +30 25 33.6 63.649910 15.884615 n.a. n.a. 0.999186876216 2.1728475 0.06060584625517 5.7829952 94.3205 /L 82.2131 81.9/ 1.3319 n.a. n.a. 0.2684651 1.9760221 88.052156 2024-Oct-31 07:30 08 35 57.43 +30 25 36.2 64.924392 17.671180 n.a. n.a. 0.999195594042 2.1744638 0.06062903620743 5.7823626 94.3275 /L 82.2048 82.0/ 1.3116 n.a. n.a. 0.2687718 357.26166 88.048973 2024-Oct-31 07:40 08 35 57.42 +30 25 38.9 66.182531 19.476356 n.a. n.a. 0.999204318351 2.1760800 0.06065222484311 5.7823386 94.3346 /L 82.1964 82.1/ 1.2915 n.a. n.a. 0.2704030 352.57986 88.036384 2024-Oct-31 07:50 08 35 57.38 +30 25 41.6 67.426178 21.299052 n.a. n.a. 0.999213049141 2.1776962 0.06067541460208 5.7829226 94.3418 /L 82.1880 82.2/ 1.2716 n.a. n.a. 0.2733246 347.97538 88.014626 2024-Oct-31 08:00 08 35 57.33 +30 25 44.3 68.657243 23.138224 n.a. n.a. 0.999221786413 2.1793122 0.06069860792034 5.7841133 94.3491 /L 82.1795 82.3/ 1.2519 n.a. n.a. 0.2774760 343.48814 87.984141 2024-Oct-31 08:10 08 35 57.26 +30 25 46.9 69.877707 24.992874 n.a. n.a. 0.999230530167 2.1809282 0.06072180722561 5.7859079 94.3564 /L 82.1709 82.4/ 1.2325 n.a. n.a. 0.2827740 339.15120 87.945537 2024-Oct-31 08:20 08 35 57.17 +30 25 49.5 71.089633 26.862042 n.a. n.a. 0.999239280401 2.1825442 0.06074501493271 5.7883027 94.3637 /L 82.1623 82.5/ 1.2133 n.a. n.a. 0.2891179 334.98970 87.899553 2024-Oct-31 08:30 08 35 57.07 +30 25 52.2 72.295191 28.744805 n.a. n.a. 0.999248037117 2.1841600 0.06076823343888 5.7912927 94.3711 /L 82.1536 82.6/ 1.1944 n.a. n.a. 0.2963955 331.02063 87.847019 2024-Oct-31 08:40 08 35 56.95 +30 25 54.7 73.496676 30.640273 n.a. n.a. 0.999256800312 2.1857758 0.06079146511910 5.7948717 94.3786 /L 82.1449 82.8/ 1.1757 n.a. n.a. 0.3044878 327.25343 87.788815 2024-Oct-31 08:50 08 35 56.81 +30 25 57.3 74.696537 32.547582 n.a. n.a. 0.999265569988 2.1873915 0.06081471232164 5.7990326 94.3861 /L 82.1361 82.9/ 1.1573 n.a. n.a. 0.3132738 323.69098 87.725840 2024-Oct-31 09:00 08 35 56.66 +30 25 59.8 75.897414 34.465892 n.a. n.a. 0.999274346144 2.1890071 0.06083797736354 5.8037670 94.3937 /L 82.1272 83.0/ 1.1391 n.a. n.a. 0.3226337 320.33093 87.658982 2024-Oct-31 09:10 08 35 56.49 +30 26 02.2 77.102175 36.394380 n.a. n.a. 0.999283128779 2.1906227 0.06086126252624 5.8090655 94.4013 /L 82.1183 83.1/ 1.1213 n.a. n.a. 0.3324518 317.16693 87.589101 2024-Oct-31 09:20 08 35 56.31 +30 26 04.6 78.313971 38.332237 n.a. n.a. 0.999291917893 2.1922381 0.06088457005104 5.8149175 94.4090 /L 82.1094 83.2/ 1.1037 n.a. n.a. 0.3426181 314.18989 87.517016 2024-Oct-31 09:30 08 35 56.11 +30 26 07.0 79.536296 40.278658 n.a. n.a. 0.999300713486 2.1938535 0.06090790213464 5.8213114 94.4167 /L 82.1004 83.3/ 1.0864 n.a. n.a. 0.3530291 311.38891 87.443493 2024-Oct-31 09:40 08 35 55.90 +30 26 09.3 80.773066 42.232840 n.a. n.a. 0.999309515557 2.1954689 0.06093126092547 5.8282347 94.4245 /L 82.0914 83.4/ 1.0693 n.a. n.a. 0.3635885 308.75214 87.369248 2024-Oct-31 09:50 08 35 55.67 +30 26 11.5 82.028719 44.193966 n.a. n.a. 0.999318324107 2.1970841 0.06095464851915 5.8356736 94.4323 /L 82.0823 83.5/ 1.0526 n.a. n.a. 0.3742074 306.26737 87.294937 2024-Oct-31 10:00 08 35 55.43 +30 26 13.7 83.308338 46.161205 n.a. n.a. 0.999327139134 2.1986993 0.06097806695469 5.8436135 94.4402 /L 82.0732 83.6/ 1.0362 n.a. n.a. 0.3848035 303.92245 87.221166 2024-Oct-31 10:10 08 35 55.18 +30 26 15.8 84.617809 48.133689 n.a. n.a. 0.999335960639 2.2003144 0.06100151821007 5.8520388 94.4481 /L 82.0640 83.7/ 1.0200 n.a. n.a. 0.3953018 301.70558 87.148486 2024-Oct-31 10:20 08 35 54.91 +30 26 17.8 85.964028 50.110508 n.a. n.a. 0.999344788622 2.2019294 0.06102500419923 5.8609330 94.4560 /L 82.0548 83.8/ 1.0042 n.a. n.a. 0.4056330 299.60556 87.077399 2024-Oct-31 10:30 08 35 54.63 +30 26 19.8 87.355167 52.090680 n.a. n.a. 0.999353623081 2.2035444 0.06104852676756 5.8702785 94.4640 /L 82.0455 83.9/ 0.9886 n.a. n.a. 0.4157342 297.61181 87.008360 2024-Oct-31 10:40 08 35 54.34 +30 26 21.7 88.801027 54.073133 n.a. n.a. 0.999362464017 2.2051593 0.06107208768908 5.8800573 94.4720 /L 82.0363 84.0/ 0.9734 n.a. n.a. 0.4255474 295.71448 86.941782 2024-Oct-31 10:50 08 35 54.04 +30 26 23.5 90.313513 56.056670 n.a. n.a. 0.999371311429 2.2067741 0.06109568866267 5.8902500 94.4800 /L 82.0269 84.1/ 0.9584 n.a. n.a. 0.4350201 293.90443 86.878035 2024-Oct-31 11:00 08 35 53.73 +30 26 25.2 91.907269 58.039921 n.a. n.a. 0.999380165317 2.2083888 0.06111933130887 5.9008368 94.4881 /L 82.0176 84.2/ 0.9438 n.a. n.a. 0.4441040 292.17323 86.817454 2024-Oct-31 11:10 08 35 53.40 +30 26 26.8 93.600557 60.021280 n.a. n.a. 0.999389025681 2.2100035 0.06114301716678 5.9117969 94.4962 /L 82.0082 84.3/ 0.9295 n.a. n.a. 0.4527554 290.51310 86.760337 2024-Oct-31 11:20 08 35 53.07 +30 26 28.3 95.416486 61.998820 n.a. n.a. 0.999397892521 2.2116180 0.06116674769119 5.9231091 94.5043 /L 81.9988 84.4/ 0.9155 n.a. n.a. 0.4609343 288.91689 86.706952 2024-Oct-31 11:30 08 35 52.73 +30 26 29.8 97.384743 63.970165 n.a. n.a. 0.999406765835 2.2132325 0.06119052424957 5.9347511 94.5124 /L 81.9894 84.5/ 0.9018 n.a. n.a. 0.4686046 287.37802 86.657533 2024-Oct-31 11:40 08 35 52.38 +30 26 31.1 99.544099 65.932304 n.a. n.a. 0.999415645624 2.2148470 0.06121434811939 5.9467003 94.5206 /L 81.9799 84.5/ 0.8884 n.a. n.a. 0.4757335 285.89040 86.612289 2024-Oct-31 11:50 08 35 52.02 +30 26 32.4 101.946078 67.881318 n.a. n.a. 0.999424531887 2.2164613 0.06123822048602 5.9589334 94.5288 /L 81.9705 84.6/ 0.8752 n.a. n.a. 0.4822915 284.44844 86.571401 2024-Oct-31 12:00 08 35 51.65 +30 26 33.5 104.660425 69.811949 n.a. n.a. 0.999433424625 2.2180756 0.06126214244010 5.9714265 94.5369 /L 81.9610 84.7/ 0.8624 n.a. n.a. 0.4882522 283.04694 86.535023 2024-Oct-31 12:10 08 35 51.28 +30 26 34.5 107.783362 71.716935 n.a. n.a. 0.999442323836 2.2196898 0.06128611497571 5.9841553 94.5452 /L 81.9515 84.8/ 0.8500 n.a. n.a. 0.4935921 281.68105 86.503290 2024-Oct-31 12:20 08 35 50.91 +30 26 35.5 111.450146 73.585922 n.a. n.a. 0.999451229521 2.2213039 0.06131013898850 5.9970949 94.5534 /L 81.9420 84.9/ 0.8378 n.a. n.a. 0.4982905 280.34627 86.476308 2024-Oct-31 12:30 08 35 50.53 +30 26 36.3 115.854006 75.403676 n.a. n.a. 0.999460141679 2.2229179 0.06133421527342 6.0102201 94.5616 /L 81.9324 85.0/ 0.8258 n.a. n.a. 0.5023295 279.03834 86.454168 2024-Oct-31 12:40 A 08 35 50.14 +30 26 37.0 121.273385 77.147070 n.a. n.a. 0.999469060310 2.2245319 0.06135834452369 6.0235054 94.5698 /L 81.9229 85.1/ 0.8142 n.a. n.a. 0.5056937 277.75326 86.436938 2024-Oct-31 12:50 A 08 35 49.75 +30 26 37.6 128.105443 78.780064 n.a. n.a. 0.999477985413 2.2261458 0.06138252732956 6.0369249 94.5780 /L 81.9133 85.2/ 0.8029 n.a. n.a. 0.5083702 276.48721 86.424665 2024-Oct-31 13:00 A 08 35 49.36 +30 26 38.2 136.885266 80.245806 n.a. n.a. 0.999486916989 2.2277596 0.06140676417677 6.0504524 94.5863 /L 81.9038 85.3/ 0.7919 n.a. n.a. 0.5103487 275.23653 86.417380 2024-Oct-31 13:10 Nm 08 35 48.96 +30 26 38.6 148.211690 81.456662 n.a. n.a. 0.999495855037 2.2293734 0.06143105544578 6.0640616 94.5945 /L 81.8943 85.3/ 0.7811 n.a. n.a. 0.5116213 273.99771 86.415096 2024-Oct-31 13:20 Nm 08 35 48.57 +30 26 38.8 162.395656 82.290693 n.a. n.a. 0.999504799556 2.2309870 0.06145540141109 6.0777260 94.6027 /L 81.8847 85.4/ 0.7707 n.a. n.a. 0.5121823 272.76729 86.417807 2024-Oct-31 13:30 Nm 08 35 48.17 +30 26 39.0 178.747480 82.618477 n.a. n.a. 0.999513750546 2.2326006 0.06147980224073 6.0914190 94.6109 /L 81.8752 85.5/ 0.7605 n.a. n.a. 0.5120285 271.54192 86.425494 2024-Oct-31 13:40 Ct 08 35 47.78 +30 26 39.1 195.274932 82.374252 n.a. n.a. 0.999522708008 2.2342141 0.06150425799595 6.1051139 94.6191 /L 81.8657 85.6/ 0.7506 n.a. n.a. 0.5111591 270.31825 86.438119 2024-Oct-31 13:50 Cm 08 35 47.38 +30 26 39.1 209.859212 81.607944 n.a. n.a. 0.999531671940 2.2358276 0.06152876863087 6.1187841 94.6273 /L 81.8561 85.7/ 0.7409 n.a. n.a. 0.5095755 269.09293 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/horizons_batch.txt scripts https://ssd.jpl.nasa.gov/ftp/ssd/SCRIPTS Author : Jon.D.Giorgini@jpl.nasa.gov ***************************************************************************************************************************************************************************************************************************************************