API VERSION: 1.2 API SOURCE: NASA/JPL Horizons API ****************************************************************************** Revised: Oct 28, 2024 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 trajectory from ESA 2024-Oct-27, prediction thereafter Name Start (TDB) Stop (TDB) --------------------------------------- ----------------- ----------------- hera_fcp_000025_241007_261118_v01 2024-Oct-07 16:10 2026-Nov-18 01:59 ******************************************************************************* ******************************************************************************* Ephemeris / API_USER Mon Nov 4 02:20:26 2024 Pasadena, USA / Horizons ******************************************************************************* Target body name: Hera (spacecraft) (-91) {source: hera_fcp_000025_241007_2} 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.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 2024-Oct-31 00:00 08 32 48.42 +33 41 17.8 62.070614 19.631824 n.a. n.a. 1.002716943828 2.5917061 0.07471742597584 4.9955995 95.4395 /L 80.3074 80.1/ 2.0496 n.a. n.a. 0.1884379 5.2837547 88.048778 2024-Oct-31 00:10 08 32 48.43 +33 41 19.6 63.386812 21.316709 n.a. n.a. 1.002727341098 2.5930783 0.07473745859152 4.9950877 95.4463 /L 80.2995 80.2/ 2.0248 n.a. n.a. 0.1877573 0.0492327 88.055100 2024-Oct-31 00:20 08 32 48.42 +33 41 21.5 64.689205 23.021027 n.a. n.a. 1.002737743871 2.5944504 0.07475749028042 4.9951373 95.4533 /L 80.2915 80.3/ 2.0002 n.a. n.a. 0.1882350 354.81377 88.049653 2024-Oct-31 00:30 08 32 48.40 +33 41 23.4 65.979481 24.743710 n.a. n.a. 1.002748152146 2.5958224 0.07477752329327 4.9957478 95.4603 /L 80.2835 80.4/ 1.9759 n.a. n.a. 0.1898550 349.63942 88.032595 2024-Oct-31 00:40 08 32 48.37 +33 41 25.3 67.259407 26.483728 n.a. n.a. 1.002758565924 2.5971943 0.07479755987641 4.9969175 95.4673 /L 80.2754 80.5/ 1.9518 n.a. n.a. 0.1925731 344.58346 88.004382 2024-Oct-31 00:50 08 32 48.32 +33 41 27.1 68.530841 28.240089 n.a. n.a. 1.002768985205 2.5985661 0.07481760226745 4.9986437 95.4744 /L 80.2673 80.6/ 1.9279 n.a. n.a. 0.1963211 339.69443 87.965733 2024-Oct-31 01:00 08 32 48.26 +33 41 28.9 69.795748 30.011835 n.a. n.a. 1.002779409987 2.5999379 0.07483765269095 5.0009227 95.4815 /L 80.2591 80.7/ 1.9044 n.a. n.a. 0.2010113 335.00972 87.917566 2024-Oct-31 01:10 08 32 48.18 +33 41 30.7 71.056215 31.798037 n.a. n.a. 1.002789840270 2.6013096 0.07485771335433 5.0037496 95.4886 /L 80.2509 80.8/ 1.8811 n.a. n.a. 0.2065435 330.55471 87.860941 2024-Oct-31 01:20 08 32 48.10 +33 41 32.5 72.314482 33.597793 n.a. n.a. 1.002800276055 2.6026812 0.07487778644342 5.0071185 95.4958 /L 80.2427 80.9/ 1.8580 n.a. n.a. 0.2128104 326.34348 87.796993 2024-Oct-31 01:30 08 32 47.99 +33 41 34.3 73.572963 35.410223 n.a. n.a. 1.002810717340 2.6040527 0.07489787411844 5.0110225 95.5031 /L 80.2344 81.0/ 1.8353 n.a. n.a. 0.2197026 322.38028 87.726879 2024-Oct-31 01:40 08 32 47.88 +33 41 36.0 74.834288 37.234469 n.a. n.a. 1.002821164126 2.6054241 0.07491797850976 5.0154538 95.5104 /L 80.2261 81.1/ 1.8128 n.a. n.a. 0.2271128 318.66167 87.651739 2024-Oct-31 01:50 08 32 47.75 +33 41 37.7 76.101343 39.069681 n.a. n.a. 1.002831616412 2.6067955 0.07493810171387 5.0204032 95.5177 /L 80.2177 81.2/ 1.7907 n.a. n.a. 0.2349382 315.17857 87.572664 2024-Oct-31 02:00 08 32 47.61 +33 41 39.3 77.377323 40.915023 n.a. n.a. 1.002842074198 2.6081668 0.07495824578936 5.0258609 95.5250 /L 80.2093 81.3/ 1.7688 n.a. n.a. 0.2430823 311.91811 87.490677 2024-Oct-31 02:10 08 32 47.46 +33 41 40.9 78.665801 42.769659 n.a. n.a. 1.002852537483 2.6095380 0.07497841275292 5.0318159 95.5324 /L 80.2008 81.4/ 1.7473 n.a. n.a. 0.2514558 308.86522 87.406726 2024-Oct-31 02:20 08 32 47.30 +33 41 42.5 79.970810 44.632749 n.a. n.a. 1.002863006267 2.6109091 0.07499860457554 5.0382564 95.5399 /L 80.1923 81.5/ 1.7261 n.a. n.a. 0.2599766 306.00382 87.321679 2024-Oct-31 02:30 08 32 47.13 +33 41 44.0 81.296948 46.503439 n.a. n.a. 1.002873480550 2.6122801 0.07501882317869 5.0451696 95.5473 /L 80.1838 81.6/ 1.7052 n.a. n.a. 0.2685701 303.31760 87.236323 2024-Oct-31 02:40 08 32 46.94 +33 41 45.4 82.649512 48.380852 n.a. n.a. 1.002883960331 2.6136511 0.07503907043064 5.0525417 95.5548 /L 80.1753 81.7/ 1.6846 n.a. n.a. 0.2771686 300.79070 87.151373 2024-Oct-31 02:50 08 32 46.74 +33 41 46.8 84.034667 50.264076 n.a. n.a. 1.002894445610 2.6150219 0.07505934814288 5.0603581 95.5624 /L 80.1667 81.8/ 1.6644 n.a. n.a. 0.2857108 298.40796 87.067468 2024-Oct-31 03:00 08 32 46.54 +33 41 48.1 85.459667 52.152144 n.a. n.a. 1.002904936387 2.6163927 0.07507965806663 5.0686034 95.5699 /L 80.1580 81.9/ 1.6445 n.a. n.a. 0.2941411 296.15522 86.985185 2024-Oct-31 03:10 08 32 46.32 +33 41 49.4 86.933144 54.044019 n.a. n.a. 1.002915432661 2.6177634 0.07510000188947 5.0772613 95.5775 /L 80.1494 82.0/ 1.6249 n.a. n.a. 0.3024094 294.01935 86.905039 2024-Oct-31 03:20 08 32 46.09 +33 41 50.6 88.465492 55.938562 n.a. n.a. 1.002925934433 2.6191341 0.07512038123220 5.0863148 95.5851 /L 80.1407 82.1/ 1.6056 n.a. n.a. 0.3104706 291.98829 86.827491 2024-Oct-31 03:30 08 32 45.86 +33 41 51.7 90.069370 57.834497 n.a. n.a. 1.002936441701 2.6205046 0.07514079764559 5.0957460 95.5928 /L 80.1320 82.2/ 1.5867 n.a. n.a. 0.3182836 290.05100 86.752949 2024-Oct-31 03:40 08 32 45.61 +33 41 52.7 91.760406 59.730364 n.a. n.a. 1.002946954465 2.6218751 0.07516125260747 5.1055364 95.6005 /L 80.1233 82.2/ 1.5682 n.a. n.a. 0.3258116 288.19745 86.681780 2024-Oct-31 03:50 08 32 45.36 +33 41 53.7 93.558144 61.624451 n.a. n.a. 1.002957472725 2.6232455 0.07518174751986 5.1156667 95.6081 /L 80.1145 82.3/ 1.5500 n.a. n.a. 0.3330211 286.41847 86.614303 2024-Oct-31 04:00 08 32 45.10 +33 41 54.6 95.487376 63.514696 n.a. n.a. 1.002967996482 2.6246158 0.07520228370632 5.1261171 95.6158 /L 80.1058 82.4/ 1.5321 n.a. n.a. 0.3398822 284.70575 86.550804 2024-Oct-31 04:10 08 32 44.84 +33 41 55.4 97.580041 65.398556 n.a. n.a. 1.002978525733 2.6259860 0.07522286240944 5.1368670 95.6236 /L 80.0970 82.5/ 1.5146 n.a. n.a. 0.3463679 283.05169 86.491530 2024-Oct-31 04:20 08 32 44.56 +33 41 56.1 99.877942 67.272800 n.a. n.a. 1.002989060479 2.6273562 0.07524348478829 5.1478953 95.6313 /L 80.0882 82.6/ 1.4974 n.a. n.a. 0.3524539 281.44934 86.436695 2024-Oct-31 04:30 08 32 44.28 +33 41 56.8 102.436748 69.133211 n.a. n.a. 1.002999600721 2.6287262 0.07526415191643 5.1591805 95.6390 /L 80.0794 82.7/ 1.4805 n.a. n.a. 0.3581187 279.89236 86.386484 2024-Oct-31 04:40 08 32 44.00 +33 41 57.4 105.331929 70.974123 n.a. n.a. 1.003010146456 2.6300962 0.07528486477960 5.1707004 95.6468 /L 80.0705 82.8/ 1.4640 n.a. n.a. 0.3633431 278.37488 86.341052 2024-Oct-31 04:50 08 32 43.71 +33 41 57.8 108.667669 72.787685 n.a. n.a. 1.003020697685 2.6314661 0.07530562427401 5.1824324 95.6546 /L 80.0617 82.9/ 1.4479 n.a. n.a. 0.3681105 276.89151 86.300528 2024-Oct-31 05:00 08 32 43.41 +33 41 58.2 112.590278 74.562685 n.a. n.a. 1.003031254409 2.6328360 0.07532643120458 5.1943537 95.6624 /L 80.0528 83.0/ 1.4321 n.a. n.a. 0.3724062 275.43721 86.265015 2024-Oct-31 05:10 08 32 43.11 +33 41 58.5 117.307947 76.282597 n.a. n.a. 1.003041816625 2.6342057 0.07534728628333 5.2064408 95.6701 /L 80.0440 83.1/ 1.4166 n.a. n.a. 0.3762178 274.00728 86.234592 2024-Oct-31 05:20 A 08 32 42.81 +33 41 58.7 123.117777 77.922356 n.a. n.a. 1.003052384335 2.6355754 0.07536819012801 5.2186701 95.6779 /L 80.0351 83.1/ 1.4014 n.a. n.a. 0.3795350 272.59731 86.209316 2024-Oct-31 05:30 A 08 32 42.50 +33 41 58.9 130.434586 79.443097 n.a. n.a. 1.003062957537 2.6369449 0.07538914326101 5.2310176 95.6857 /L 80.0262 83.2/ 1.3866 n.a. n.a. 0.3823493 271.20311 86.189221 2024-Oct-31 05:40 Am 08 32 42.20 +33 41 58.9 139.791357 80.784365 n.a. n.a. 1.003073536231 2.6383144 0.07541014610834 5.2434593 95.6935 /L 80.0173 83.3/ 1.3721 n.a. n.a. 0.3846544 269.82067 86.174322 2024-Oct-31 05:50 Nm 08 32 41.89 +33 41 58.8 151.715216 81.855825 n.a. n.a. 1.003084120418 2.6396839 0.07543119899861 5.2559708 95.7013 /L 80.0085 83.4/ 1.3579 n.a. n.a. 0.3864458 268.44614 86.164614 2024-Oct-31 06:00 Nm 08 32 41.58 +33 41 58.6 166.305869 82.539410 n.a. n.a. 1.003094710096 2.6410532 0.07545230216272 5.2685276 95.7090 /L 79.9996 83.5/ 1.3441 n.a. n.a. 0.3877209 267.07580 86.160070 2024-Oct-31 06:10 Nt 08 32 41.27 +33 41 58.4 182.583774 82.724428 n.a. n.a. 1.003105305266 2.6424225 0.07547345573318 5.2811052 95.7168 /L 79.9907 83.5/ 1.3305 n.a. n.a. 0.3884788 265.70600 86.160649 2024-Oct-31 06:20 Cm 08 32 40.96 +33 41 58.0 198.518239 82.374373 n.a. n.a. 1.003115905926 2.6437916 0.07549465974393 5.2936789 95.7246 /L 79.9819 83.6/ 1.3173 n.a. n.a. 0.3887209 264.33314 86.166288 2024-Oct-31 06:30 Cm 08 32 40.65 +33 41 57.6 212.316063 81.555745 n.a. n.a. 1.003126512078 2.6451607 0.07551591413026 5.3062242 95.7323 /L 79.9730 83.7/ 1.3044 n.a. n.a. 0.3884500 262.95363 86.176910 >..... Daylight Cut-off Requested .....< >..... Elevation Cut-off Requested .....< 2024-Oct-31 21:50 08 32 46.46 +33 40 20.6 43.691869 0.574557 n.a. n.a. 1.004125724707 2.7707642 0.07750081583733 5.0113873 96.3228 /L 79.2785 90.3/ 0.4243 n.a. n.a. 0.2461356 52.026155 87.365560 2024-Oct-31 22:00 08 32 46.61 +33 40 22.2 45.302892 1.902931 n.a. n.a. 1.004136840100 2.7721256 0.07752089839479 5.0041891 96.3292 /L 79.2711 90.4/ 0.4136 n.a. n.a. 0.2383667 49.019465 87.444273 2024-Oct-31 22:10 08 32 46.75 +33 40 23.7 46.883810 3.268458 n.a. n.a. 1.004147960954 2.7734869 0.07754095304089 4.9974696 96.3356 /L 79.2637 90.5/ 0.4031 n.a. n.a. 0.2307971 45.817622 87.521367 2024-Oct-31 22:20 08 32 46.87 +33 40 25.4 48.435535 4.669421 n.a. n.a. 1.004159087267 2.7748481 0.07756098172029 4.9912411 96.3421 /L 79.2562 90.6/ 0.3927 n.a. n.a. 0.2235091 42.407016 87.595931 2024-Oct-31 22:30 08 32 46.99 +33 40 27.0 49.959064 6.104152 n.a. n.a. 1.004170219039 2.7762092 0.07758098642540 4.9855150 96.3486 /L 79.2486 90.7/ 0.3824 n.a. n.a. 0.2165913 38.776099 87.666981 2024-Oct-31 22:40 08 32 47.09 +33 40 28.8 51.455474 7.571041 n.a. n.a. 1.004181356271 2.7775702 0.07760096919266 4.9803019 96.3551 /L 79.2410 90.8/ 0.3722 n.a. n.a. 0.2101380 34.916723 87.733470 2024-Oct-31 22:50 08 32 47.18 +33 40 30.5 52.925914 9.068533 n.a. n.a. 1.004192498961 2.7789312 0.07762093209844 4.9756113 96.3617 /L 79.2334 90.9/ 0.3622 n.a. n.a. 0.2042475 30.825755 87.794300 2024-Oct-31 23:00 08 32 47.26 +33 40 32.3 54.371594 10.595127 n.a. n.a. 1.004203647110 2.7802920 0.07764087725534 4.9714516 96.3683 /L 79.2258 91.0/ 0.3523 n.a. n.a. 0.1990196 26.506858 87.848354 2024-Oct-31 23:10 08 32 47.32 +33 40 34.1 55.793783 12.149380 n.a. n.a. 1.004214800717 2.7816528 0.07766080680798 4.9678303 96.3750 /L 79.2181 91.1/ 0.3425 n.a. n.a. 0.1945527 21.972240 87.894530 2024-Oct-31 23:20 08 32 47.37 +33 40 35.9 57.193801 13.729902 n.a. n.a. 1.004225959781 2.7830135 0.07768072292893 4.9647540 96.3817 /L 79.2103 91.2/ 0.3329 n.a. n.a. 0.1909397 17.244030 87.931788 2024-Oct-31 23:30 08 32 47.41 +33 40 37.7 58.573022 15.335357 n.a. n.a. 1.004237124302 2.7843741 0.07770062781456 4.9622279 96.3885 /L 79.2025 91.3/ 0.3234 n.a. n.a. 0.1882622 12.354904 87.959205 2024-Oct-31 23:40 08 32 47.44 +33 40 39.6 59.932870 16.964464 n.a. n.a. 1.004248294280 2.7857346 0.07772052368089 4.9602565 96.3953 /L 79.1946 91.4/ 0.3141 n.a. n.a. 0.1865864 7.3475616 87.976036 2024-Oct-31 23:50 08 32 47.45 +33 40 41.4 61.274817 18.615988 n.a. n.a. 1.004259469715 2.7870950 0.07774041275922 4.9588431 96.4022 /L 79.1868 91.5/ 0.3050 n.a. n.a. 0.1859573 2.2728387 87.981763 2024-Nov-01 00:00 08 32 47.45 +33 40 43.3 62.600390 20.288747 n.a. n.a. 1.004270650606 2.7884554 0.07776029729203 4.9579898 96.4091 /L 79.1788 91.6/ 0.2960 n.a. n.a. 0.1863962 357.18654 87.976138 $$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 ***************************************************************************************************************************************************************************************************************************************************