API VERSION: 1.2 API SOURCE: NASA/JPL Horizons API ****************************************************************************** Revised: Jun 06, 2025 Hera / (Sun) -91 https://www.dlr.de/en/ar/topics-missions/space-safety/hera https://esamultimedia.esa.int/docs/HERA_Launch_Kit.pdf Launch Date: Didymos Arrival Date: 2024-Oct-07 14:52 UTC Late 2026 Launch Vehicle: Launch Site: SpaceX Falcon 9 Cape Canaveral, SFS MILESTONES 2024-Nov : DSM-1 2025-Mar : Mars flyby (~6000 km from Mars, ~1000 km from Deimos) 2026-Feb : DSM-2 2026-Oct : Rendevous maneuver Late 2026 : Didymos/Dimorphos system arrival OBJECTIVES: Assess the size and depth of the crater on the 151-m diameter asteroidal moon Dimorphos, created by NASA's DART (Double Asteroid Redirection Test) spacecraft 2022-Sep-26, and determine whether the impact reshaped the rubble pile object that orbits 65803 Didymos at a distance of 1.1 km every 11h 22m, as preliminary results indicate. Once deployed, two CubeSats ("Milani" and "Juventas") will be used to assess Dimorphos' internal structure, surface minerals, as well as gravity. The data will help correctly reproduce the asteroid's final structure and inform future planetary defense missions. SPACECRAFT PHYSICAL PROPERTIES: 1.6 x 1.6 x 1.7 m box Two 5-m solar panel arms (deployed) 1801 kg fully fueled (hydrazine bipropellant) 3-axis stabilization 4 reaction wheels, gyroscopes, star trackers, solar sensors SCIENCE INSTRUMENTS Asteroid Framing Camera (AFC) Thermal Infrared Imager (TIRI) HyperScout-H camera Spacecraft Monitoring Camera (SMC) Laser Rangefinder X-band antenna radio science Gravimeter for the Investigation of Small Solar System Two deployable CubeSats (eventual landing) Juventas: Radar Juventas: Narrow Angle Camera Milani : Narrow Angle Camera Milani : Asteroid Spectral Imager Milani : Volatile In-Situ Thermogravimetre Analyser SPACECRAFT TRAJECTORY: Post-launch tracking-data based trajectory from ESA 2025-May-27. Prediction thereafter. Name Start (TDB) Stop (TDB) --------------------------------------- ----------------- ----------------- hera_fcp_000051_241007_261118_v01 2024-Oct-07 16:10 2026-Nov-18 01:59 ******************************************************************************* ******************************************************************************* Ephemeris / API_USER Sun Jun 22 10:07:45 2025 Pasadena, USA / Horizons ******************************************************************************* Target body name: Hera (spacecraft) (-91) {source: hera_current} Center body name: Earth (399) {source: DE441} Center-site name: El Berrueco ******************************************************************************* 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 : 356.4134, 40.8833094, 1.06361 {E-lon(deg),Lat(deg),Alt(km)} Center cylindric: 356.4134,4829.88693,4153.33056 {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: DE441} 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.250620.p250916 EOP coverage : DATA-BASED 1962-JAN-20 TO 2025-JUN-20. PREDICTS-> 2025-SEP-15 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-Oct-31 00:00 08 32 48.43 +33 41 17.8 62.070596 19.631832 n.a. n.a. 1.002716945466 2.5917111 0.07471742665293 4.9956000 95.4395 /L 80.3074 80.1/ 2.0496 n.a. n.a. 0.1884438 5.2822963 88.048717 2024-Oct-31 00:10 08 32 48.43 +33 41 19.7 63.386794 21.316717 n.a. n.a. 1.002727342756 2.5930833 0.07473745927066 4.9950882 95.4463 /L 80.2995 80.2/ 2.0248 n.a. n.a. 0.1877636 0.0479367 88.055035 2024-Oct-31 00:20 08 32 48.43 +33 41 21.6 64.689187 23.021035 n.a. n.a. 1.002737745549 2.5944554 0.07475749096162 4.9951378 95.4533 /L 80.2915 80.3/ 2.0002 n.a. n.a. 0.1882416 354.81266 88.049584 2024-Oct-31 00:30 08 32 48.40 +33 41 23.5 65.979462 24.743717 n.a. n.a. 1.002748153845 2.5958274 0.07477752397655 4.9957483 95.4603 /L 80.2835 80.4/ 1.9759 n.a. n.a. 0.1898619 349.63850 88.032523 2024-Oct-31 00:40 08 32 48.37 +33 41 25.3 67.259388 26.483735 n.a. n.a. 1.002758567643 2.5971993 0.07479756056173 4.9969180 95.4673 /L 80.2754 80.5/ 1.9518 n.a. n.a. 0.1925804 344.58273 88.004308 2024-Oct-31 00:50 08 32 48.32 +33 41 27.2 68.530822 28.240096 n.a. n.a. 1.002768986943 2.5985712 0.07481760295483 4.9986442 95.4744 /L 80.2673 80.6/ 1.9279 n.a. n.a. 0.1963285 339.69390 87.965656 2024-Oct-31 01:00 08 32 48.26 +33 41 29.0 69.795728 30.011842 n.a. n.a. 1.002779411746 2.5999429 0.07483765338042 5.0009232 95.4815 /L 80.2591 80.7/ 1.9044 n.a. n.a. 0.2010188 335.00937 87.917488 2024-Oct-31 01:10 08 32 48.18 +33 41 30.8 71.056195 31.798044 n.a. n.a. 1.002789842050 2.6013146 0.07485771404587 5.0037500 95.4886 /L 80.2509 80.8/ 1.8811 n.a. n.a. 0.2065511 330.55454 87.860862 2024-Oct-31 01:20 08 32 48.10 +33 41 32.6 72.314461 33.597799 n.a. n.a. 1.002800277855 2.6026862 0.07487778713700 5.0071190 95.4958 /L 80.2427 80.9/ 1.8580 n.a. n.a. 0.2128180 326.34345 87.796914 2024-Oct-31 01:30 08 32 48.00 +33 41 34.3 73.572942 35.410230 n.a. n.a. 1.002810719160 2.6040578 0.07489787481411 5.0110231 95.5031 /L 80.2344 81.0/ 1.8353 n.a. n.a. 0.2197102 322.38039 87.726801 2024-Oct-31 01:40 08 32 47.88 +33 41 36.1 74.834266 37.234475 n.a. n.a. 1.002821165967 2.6054292 0.07491797920751 5.0154543 95.5104 /L 80.2261 81.1/ 1.8128 n.a. n.a. 0.2271204 318.66190 87.651661 2024-Oct-31 01:50 08 32 47.75 +33 41 37.7 76.101320 39.069687 n.a. n.a. 1.002831618273 2.6068006 0.07493810241369 5.0204037 95.5177 /L 80.2177 81.2/ 1.7907 n.a. n.a. 0.2349458 315.17890 87.572586 2024-Oct-31 02:00 08 32 47.62 +33 41 39.4 77.377300 40.915029 n.a. n.a. 1.002842076079 2.6081719 0.07495824649125 5.0258614 95.5250 /L 80.2093 81.3/ 1.7688 n.a. n.a. 0.2430898 311.91853 87.490600 2024-Oct-31 02:10 08 32 47.46 +33 41 41.0 78.665777 42.769665 n.a. n.a. 1.002852539385 2.6095431 0.07497841345688 5.0318164 95.5324 /L 80.2008 81.4/ 1.7473 n.a. n.a. 0.2514631 308.86572 87.406650 2024-Oct-31 02:20 08 32 47.30 +33 41 42.5 79.970785 44.632754 n.a. n.a. 1.002863008189 2.6109142 0.07499860528156 5.0382569 95.5399 /L 80.1923 81.5/ 1.7261 n.a. n.a. 0.2599838 306.00437 87.321604 2024-Oct-31 02:30 08 32 47.13 +33 41 44.0 81.296922 46.503444 n.a. n.a. 1.002873482493 2.6122853 0.07501882388676 5.0451701 95.5473 /L 80.1838 81.6/ 1.7052 n.a. n.a. 0.2685772 303.31821 87.236251 2024-Oct-31 02:40 08 32 46.94 +33 41 45.5 82.649485 48.380857 n.a. n.a. 1.002883962295 2.6136562 0.07503907114076 5.0525422 95.5548 /L 80.1753 81.7/ 1.6846 n.a. n.a. 0.2771756 300.79135 87.151301 2024-Oct-31 02:50 08 32 46.74 +33 41 46.9 84.034639 50.264081 n.a. n.a. 1.002894447595 2.6150271 0.07505934885502 5.0603586 95.5624 /L 80.1667 81.8/ 1.6644 n.a. n.a. 0.2857176 298.40865 87.067398 2024-Oct-31 03:00 08 32 46.54 +33 41 48.2 85.459637 52.152149 n.a. n.a. 1.002904938392 2.6163979 0.07507965878082 5.0686039 95.5699 /L 80.1580 81.9/ 1.6445 n.a. n.a. 0.2941478 296.15594 86.985117 2024-Oct-31 03:10 08 32 46.32 +33 41 49.4 86.933114 54.044024 n.a. n.a. 1.002915434688 2.6177686 0.07510000260571 5.0772619 95.5775 /L 80.1494 82.0/ 1.6249 n.a. n.a. 0.3024160 294.02010 86.904972 2024-Oct-31 03:20 08 32 46.09 +33 41 50.6 88.465460 55.938567 n.a. n.a. 1.002925936480 2.6191393 0.07512038195049 5.0863153 95.5851 /L 80.1407 82.1/ 1.6056 n.a. n.a. 0.3104770 291.98906 86.827425 2024-Oct-31 03:30 08 32 45.86 +33 41 51.7 90.069337 57.834502 n.a. n.a. 1.002936443769 2.6205098 0.07514079836592 5.0957465 95.5928 /L 80.1320 82.2/ 1.5867 n.a. n.a. 0.3182899 290.05179 86.752886 2024-Oct-31 03:40 08 32 45.62 +33 41 52.8 91.760371 59.730369 n.a. n.a. 1.002946956554 2.6218803 0.07516125332983 5.1055369 95.6005 /L 80.1233 82.2/ 1.5682 n.a. n.a. 0.3258177 288.19825 86.681717 2024-Oct-31 03:50 08 32 45.36 +33 41 53.8 93.558106 61.624456 n.a. n.a. 1.002957474835 2.6232507 0.07518174824424 5.1156672 95.6081 /L 80.1145 82.3/ 1.5500 n.a. n.a. 0.3330272 286.41929 86.614242 2024-Oct-31 04:00 08 32 45.10 +33 41 54.7 95.487336 63.514702 n.a. n.a. 1.002967998612 2.6246210 0.07520228443273 5.1261176 95.6158 /L 80.1058 82.4/ 1.5321 n.a. n.a. 0.3398881 284.70658 86.550745 2024-Oct-31 04:10 08 32 44.84 +33 41 55.5 97.579998 65.398561 n.a. n.a. 1.002978527885 2.6259913 0.07522286313787 5.1368675 95.6236 /L 80.0970 82.5/ 1.5146 n.a. n.a. 0.3463736 283.05253 86.491472 2024-Oct-31 04:20 08 32 44.56 +33 41 56.2 99.877896 67.272805 n.a. n.a. 1.002989062652 2.6273614 0.07524348551872 5.1478958 95.6313 /L 80.0882 82.6/ 1.4974 n.a. n.a. 0.3524595 281.45019 86.436638 2024-Oct-31 04:30 08 32 44.28 +33 41 56.9 102.436698 69.133217 n.a. n.a. 1.002999602914 2.6287315 0.07526415264886 5.1591810 95.6390 /L 80.0794 82.7/ 1.4805 n.a. n.a. 0.3581242 279.89322 86.386429 2024-Oct-31 04:40 08 32 44.00 +33 41 57.4 105.331875 70.974129 n.a. n.a. 1.003010148671 2.6301015 0.07528486551400 5.1707009 95.6468 /L 80.0705 82.8/ 1.4640 n.a. n.a. 0.3633485 278.37575 86.340998 2024-Oct-31 04:50 08 32 43.71 +33 41 57.9 108.667610 72.787693 n.a. n.a. 1.003020699921 2.6314714 0.07530562501042 5.1824329 95.6546 /L 80.0617 82.9/ 1.4479 n.a. n.a. 0.3681157 276.89239 86.300476 2024-Oct-31 05:00 08 32 43.41 +33 41 58.3 112.590214 74.562693 n.a. n.a. 1.003031256666 2.6328412 0.07532643194297 5.1943542 95.6624 /L 80.0528 83.0/ 1.4321 n.a. n.a. 0.3724113 275.43810 86.264964 2024-Oct-31 05:10 08 32 43.11 +33 41 58.6 117.307876 76.282606 n.a. n.a. 1.003041818903 2.6342110 0.07534728702368 5.2064413 95.6701 /L 80.0439 83.1/ 1.4166 n.a. n.a. 0.3762228 274.00818 86.234543 2024-Oct-31 05:20 A 08 32 42.81 +33 41 58.8 123.117700 77.922366 n.a. n.a. 1.003052386634 2.6355807 0.07536819087033 5.2186706 95.6779 /L 80.0351 83.1/ 1.4014 n.a. n.a. 0.3795398 272.59822 86.209268 2024-Oct-31 05:30 A 08 32 42.50 +33 41 58.9 130.434505 79.443109 n.a. n.a. 1.003062959858 2.6369503 0.07538914400530 5.2310181 95.6857 /L 80.0262 83.2/ 1.3866 n.a. n.a. 0.3823540 271.20402 86.189175 2024-Oct-31 05:40 Am 08 32 42.20 +33 41 58.9 139.791275 80.784379 n.a. n.a. 1.003073538574 2.6383198 0.07541014685456 5.2434598 95.6935 /L 80.0173 83.3/ 1.3721 n.a. n.a. 0.3846590 269.82159 86.174278 2024-Oct-31 05:50 Nm 08 32 41.89 +33 41 58.9 151.715142 81.855841 n.a. n.a. 1.003084122781 2.6396892 0.07543119974681 5.2559713 95.7013 /L 80.0085 83.4/ 1.3579 n.a. n.a. 0.3864502 268.44708 86.164571 2024-Oct-31 06:00 Nm 08 32 41.58 +33 41 58.7 166.305818 82.539428 n.a. n.a. 1.003094712481 2.6410585 0.07545230291286 5.2685281 95.7090 /L 79.9996 83.5/ 1.3441 n.a. n.a. 0.3877251 267.07675 86.160029 2024-Oct-31 06:10 Nt 08 32 41.27 +33 41 58.5 182.583759 82.724447 n.a. n.a. 1.003105307672 2.6424278 0.07547345648525 5.2811056 95.7168 /L 79.9907 83.5/ 1.3305 n.a. n.a. 0.3884829 265.70696 86.160609 2024-Oct-31 06:20 Cm 08 32 40.96 +33 41 58.1 198.518261 82.374391 n.a. n.a. 1.003115908354 2.6437970 0.07549466049793 5.2936794 95.7246 /L 79.9819 83.6/ 1.3173 n.a. n.a. 0.3887248 264.33411 86.166250 2024-Oct-31 06:30 Cm 08 32 40.65 +33 41 57.7 212.316109 81.555762 n.a. n.a. 1.003126514527 2.6451661 0.07551591488619 5.3062247 95.7323 /L 79.9730 83.7/ 1.3044 n.a. n.a. 0.3884538 262.95462 86.176873 >..... Daylight Cut-off Requested .....< >..... Elevation Cut-off Requested .....< 2024-Oct-31 21:50 08 32 46.46 +33 40 20.7 43.691856 0.574572 n.a. n.a. 1.004125729292 2.7707704 0.07750081678736 5.0113880 96.3228 /L 79.2785 90.3/ 0.4243 n.a. n.a. 0.2461352 52.024272 87.365564 2024-Oct-31 22:00 08 32 46.61 +33 40 22.2 45.302878 1.902946 n.a. n.a. 1.004136844710 2.7721318 0.07752089934748 5.0041898 96.3292 /L 79.2711 90.4/ 0.4136 n.a. n.a. 0.2383668 49.017518 87.444273 2024-Oct-31 22:10 08 32 46.75 +33 40 23.8 46.883796 3.268473 n.a. n.a. 1.004147965589 2.7734931 0.07754095399624 4.9974703 96.3356 /L 79.2637 90.5/ 0.4031 n.a. n.a. 0.2307976 45.815613 87.521362 2024-Oct-31 22:20 08 32 46.87 +33 40 25.4 48.435520 4.669435 n.a. n.a. 1.004159091927 2.7748543 0.07756098267830 4.9912418 96.3421 /L 79.2562 90.6/ 0.3927 n.a. n.a. 0.2235101 42.404951 87.595921 2024-Oct-31 22:30 08 32 46.99 +33 40 27.1 49.959049 6.104166 n.a. n.a. 1.004170223724 2.7762154 0.07758098738608 4.9855157 96.3486 /L 79.2486 90.7/ 0.3824 n.a. n.a. 0.2165928 38.773988 87.666966 2024-Oct-31 22:40 08 32 47.09 +33 40 28.8 51.455459 7.571055 n.a. n.a. 1.004181360981 2.7775765 0.07760097015599 4.9803026 96.3551 /L 79.2410 90.8/ 0.3722 n.a. n.a. 0.2101401 34.914578 87.733448 2024-Oct-31 22:50 08 32 47.18 +33 40 30.6 52.925899 9.068546 n.a. n.a. 1.004192503697 2.7789374 0.07762093306450 4.9756120 96.3617 /L 79.2334 90.9/ 0.3622 n.a. n.a. 0.2042500 30.823592 87.794272 2024-Oct-31 23:00 08 32 47.26 +33 40 32.3 54.371578 10.595140 n.a. n.a. 1.004203651870 2.7802983 0.07764087822410 4.9714523 96.3683 /L 79.2258 91.0/ 0.3523 n.a. n.a. 0.1990227 26.504699 87.848320 2024-Oct-31 23:10 08 32 47.32 +33 40 34.1 55.793766 12.149393 n.a. n.a. 1.004214805502 2.7816591 0.07766080777946 4.9678310 96.3750 /L 79.2180 91.1/ 0.3425 n.a. n.a. 0.1945565 21.970110 87.894490 2024-Oct-31 23:20 08 32 47.37 +33 40 36.0 57.193784 13.729914 n.a. n.a. 1.004225964591 2.7830198 0.07768072390314 4.9647546 96.3818 /L 79.2103 91.2/ 0.3329 n.a. n.a. 0.1909440 17.241957 87.931742 2024-Oct-31 23:30 08 32 47.41 +33 40 37.8 58.573005 15.335369 n.a. n.a. 1.004237129138 2.7843804 0.07770062879152 4.9622286 96.3885 /L 79.2025 91.3/ 0.3234 n.a. n.a. 0.1882671 12.352920 87.959153 2024-Oct-31 23:40 08 32 47.44 +33 40 39.6 59.932852 16.964475 n.a. n.a. 1.004248299142 2.7857409 0.07772052466057 4.9602572 96.3953 /L 79.1946 91.4/ 0.3141 n.a. n.a. 0.1865918 7.3456961 87.975977 2024-Oct-31 23:50 08 32 47.45 +33 40 41.5 61.274799 18.616000 n.a. n.a. 1.004259474602 2.7871013 0.07774041374164 4.9588437 96.4022 /L 79.1868 91.5/ 0.3050 n.a. n.a. 0.1859633 2.2711204 87.981698 2024-Nov-01 00:00 08 32 47.45 +33 40 43.3 62.600372 20.288758 n.a. n.a. 1.004270655518 2.7884617 0.07776029827719 4.9579905 96.4091 /L 79.1788 91.6/ 0.2960 n.a. n.a. 0.1864026 357.18499 87.976069 $$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 ***************************************************************************************************************************************************************************************************************************************************