API VERSION: 1.2 API SOURCE: NASA/JPL Horizons API ******************************************************************************* Revised: Nov 09, 2025 MMS-4 Spacecraft / (Earth) -140485 https://www.nasa.gov/mission_pages/mms/index.html MMS 4 Magnetospheric Multiscale (MMS) mission: the fourth of four identically instrumented space physics spacecraft studying the Earth's magnetosphere. Octagonal in shape; 2.5-m wide, 1.2-m high, spinning at 3 rpm during science operations. Eight deployable booms: four 60-meter wire booms, two 12.5 meter booms, two 5-m booms. Mass: 1250 kg; 318 W power generation; S-band communications. NOTE: The spacecraft may be maneuvered frequently. Therefore, the JSpOC TLE-based trajectory provided here may at times depart from the actual trajectory. This can happen because TLEs do not model thruster firings; the TLE trajectory solutions must be reinitialized after each event. Launched: 2015-Mar-13 02:44 UTC (Atlas V, Cape Canaveral, USA) ******************************************************************************* ******************************************************************************* Ephemeris / API_USER Sun Nov 9 14:55:13 2025 Pasadena, USA / Horizons ******************************************************************************* Target body name: MMS-4 (spacecraft) (-140485) {source: MMS-4} Center body name: Earth (399) {source: DE441} Center-site name: VdS Remote Observatory, Hakos ******************************************************************************* 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 : 16.3613, -23.2365766, 1.8515 {E-lon(deg),Lat(deg),Alt(km)} Center cylindric: 16.3613,5865.52307,-2501.54567 {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.251107.p260203 EOP coverage : DATA-BASED 1962-JAN-20 TO 2025-NOV-07. PREDICTS-> 2026-FEB-02 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 00 23 01.95 +13 00 41.5 301.393872 28.985309 n.a. n.a. 0.993215449488 -2.3175228 0.00040893321924 -2.1980711 151.2330 /T 28.7554 166.0/ 2.0498 n.a. n.a. 249.72740 15.003462 -60.68065 2024-Oct-31 00:10 00 23 48.15 +13 41 49.2 300.530663 26.760220 n.a. n.a. 0.993206054314 -2.3704524 0.00040005684369 -2.2299950 151.4725 /T 28.5162 165.9/ 2.0246 n.a. n.a. 261.59752 15.504945 -60.43358 2024-Oct-31 00:20 00 24 38.26 +14 24 50.3 299.766920 24.523707 n.a. n.a. 0.993196441049 -2.4263201 0.00039104776648 -2.2643018 151.7142 /T 28.2748 165.8/ 1.9998 n.a. n.a. 274.52808 15.996828 -60.18202 2024-Oct-31 00:30 00 25 32.66 +15 09 55.0 299.099927 22.278168 n.a. n.a. 0.993186597354 -2.4854089 0.00038189613540 -2.3011427 151.9568 /T 28.0326 165.6/ 1.9753 n.a. n.a. 288.65936 16.476134 -59.92491 2024-Oct-31 00:40 00 26 31.73 +15 57 14.9 298.528219 20.025874 n.a. n.a. 0.993176509677 -2.5480419 0.00037259146422 -2.3406831 152.1986 /T 27.7911 165.5/ 1.9512 n.a. n.a. 304.15634 16.939938 -59.66103 2024-Oct-31 00:50 00 27 35.93 +16 47 03.2 298.051594 17.769028 n.a. n.a. 0.993166163082 -2.6145886 0.00036312257162 -2.3831048 152.4374 /T 27.5526 165.2/ 1.9275 n.a. n.a. 321.21437 17.385379 -59.38894 2024-Oct-31 01:00 00 28 45.79 +17 39 35.5 297.671158 15.509810 n.a. n.a. 0.993155541040 -2.6854747 0.00035347750959 -2.4286091 152.6706 /T 27.3198 165.0/ 1.9041 n.a. n.a. 340.06635 17.809661 -59.10701 2024-Oct-31 01:10 00 30 01.89 +18 35 09.3 297.389415 13.250442 n.a. n.a. 0.993144625185 -2.7611926 0.00034364347959 -2.4774198 152.8943 /T 27.0963 164.7/ 1.8811 n.a. n.a. 360.99217 18.210061 -58.81331 2024-Oct-31 01:20 00 31 24.93 +19 34 05.6 297.210395 10.993246 n.a. n.a. 0.993133395021 -2.8423159 0.00033360673372 -2.5297873 153.1041 /T 26.8869 164.3/ 1.8585 n.a. n.a. 384.33093 18.583941 -58.50561 2024-Oct-31 01:30 00 32 55.70 +20 36 48.4 297.139845 8.740726 n.a. n.a. 0.993121827561 -2.9295162 0.00032335245828 -2.5859940 153.2938 /T 26.6975 163.8/ 1.8362 n.a. n.a. 410.49713 18.928745 -58.18127 2024-Oct-31 01:40 00 34 35.14 +21 43 46.4 297.185488 6.495661 n.a. n.a. 0.993109896889 -3.0235859 0.00031286463639 -2.6463589 153.4558 /T 26.5359 163.3/ 1.8144 n.a. n.a. 440.00238 19.242019 -57.83719 2024-Oct-31 01:50 00 36 24.40 +22 55 33.7 297.357377 4.261223 n.a. n.a. 0.993097573628 -3.1254663 0.00030212588544 -2.7112455 153.5800 /T 26.4120 162.7/ 1.7929 n.a. n.a. 473.48486 19.521415 -57.46968 2024-Oct-31 02:00 00 38 24.83 +24 12 51.3 297.668363 2.041138 n.a. n.a. 0.993084824266 -3.2362842 0.00029111726503 -2.7810693 153.6537 /T 26.3386 161.9/ 1.7719 n.a. n.a. 511.74982 19.764720 -57.07430 2024-Oct-31 02:10 00 40 38.12 +25 36 28.6 298.134733 -0.160102 n.a. n.a. 0.993071610323 -3.3574000 0.00027981805053 -2.8563066 153.6604 /T 26.3322 161.1/ 1.7512 n.a. n.a. 555.82634 19.969893 -56.64572 >..... Elevation Cut-off Requested .....< >..... Daylight Cut-off Requested .....< >..... Elevation Cut-off Requested .....< 2024-Oct-31 17:20 C 22 07 48.96 -38 26 48.4 142.393912 69.953374 n.a. n.a. 0.992774295496 0.4874783 0.00074840491464 1.3636990 100.2411 /T 79.7167 108.1/ 0.7511 n.a. n.a. 54.344099 11.548914 70.175011 2024-Oct-31 17:30 C 22 07 57.82 -38 17 55.1 146.376417 71.385070 n.a. n.a. 0.992776234833 0.4841956 0.00075386750999 1.3621572 100.3292 /T 79.6282 108.1/ 0.7384 n.a. n.a. 54.646919 10.781781 69.918433 2024-Oct-31 17:40 N 22 08 06.15 -38 08 57.4 151.099512 72.684623 n.a. n.a. 0.992778161003 0.4808985 0.00075932485272 1.3610518 100.4164 /T 79.5408 108.1/ 0.7256 n.a. n.a. 54.975235 10.122221 69.658090 2024-Oct-31 17:50 N 22 08 14.02 -37 59 55.3 156.641850 73.817123 n.a. n.a. 0.992780073952 0.4775885 0.00076477862927 1.3603512 100.5029 /T 79.4540 108.2/ 0.7127 n.a. n.a. 55.322985 9.5674704 69.395675 2024-Oct-31 18:00 A 22 08 21.53 -37 50 48.9 163.033554 74.742384 n.a. n.a. 0.992781973632 0.4742667 0.00077023039782 1.3600231 100.5889 /T 79.3677 108.2/ 0.6998 n.a. n.a. 55.684768 9.1143282 69.132672 2024-Oct-31 18:10 A 22 08 28.74 -37 41 38.3 170.215204 75.418120 n.a. n.a. 0.992783859998 0.4709344 0.00077568158706 1.3600352 100.6746 /T 79.2817 108.2/ 0.6868 n.a. n.a. 56.055829 8.7592832 68.870357 2024-Oct-31 18:20 A 22 08 35.74 -37 32 23.4 178.002402 75.806095 n.a. n.a. 0.992785733010 0.4675927 0.00078113349504 1.3603548 100.7602 /T 79.1958 108.2/ 0.6738 n.a. n.a. 56.432021 8.4986161 68.609798 2024-Oct-31 18:30 t 22 08 42.60 -37 23 04.5 186.084708 75.880297 n.a. n.a. 0.992787592634 0.4642428 0.00078658728841 1.3609490 100.8459 /T 79.1097 108.2/ 0.6607 n.a. n.a. 56.809772 8.3284846 68.351861 2024-Oct-31 18:40 22 08 49.39 -37 13 41.7 194.080250 75.633922 n.a. n.a. 0.992789438839 0.4608857 0.00079204400185 1.3617849 100.9320 /T 79.0234 108.3/ 0.6475 n.a. n.a. 57.186046 8.2449905 68.097222 2024-Oct-31 18:50 22 08 56.18 -37 04 15.1 201.629289 75.081248 n.a. n.a. 0.992791271599 0.4575224 0.00079750453769 1.3628295 101.0185 /T 78.9365 108.3/ 0.6344 n.a. n.a. 57.558307 8.2442319 67.846375 2024-Oct-31 19:00 22 09 03.03 -36 54 44.8 208.475193 74.253233 n.a. n.a. 0.992793090890 0.4541538 0.00080296966592 1.3640498 101.1057 /T 78.8490 108.3/ 0.6212 n.a. n.a. 57.924471 8.3223416 67.599646 2024-Oct-31 19:10 22 09 10.00 -36 45 11.2 214.493083 73.189571 n.a. n.a. 0.992794896694 0.4507809 0.00080844002444 1.3654129 101.1938 /T 78.7607 108.3/ 0.6080 n.a. n.a. 58.282874 8.4755157 67.357209 2024-Oct-31 19:20 22 09 17.17 -36 35 34.3 219.669356 71.931160 n.a. n.a. 0.992796688996 0.4474044 0.00081391611943 1.3668861 101.2828 /T 78.6714 108.3/ 0.5948 n.a. n.a. 58.632231 8.7000322 67.119095 2024-Oct-31 19:30 22 09 24.58 -36 25 54.4 224.060753 70.515272 n.a. n.a. 0.992798467783 0.4440254 0.00081939832617 1.3684368 101.3729 /T 78.5810 108.3/ 0.5817 n.a. n.a. 58.971596 8.9922630 66.885209 2024-Oct-31 19:40 22 09 32.30 -36 16 11.7 227.756902 68.973479 n.a. n.a. 0.992800233046 0.4406444 0.00082488689005 1.3700328 101.4643 /T 78.4892 108.4/ 0.5685 n.a. n.a. 59.300328 9.3486805 66.655344 2024-Oct-31 19:50 22 09 40.37 -36 06 26.5 230.855331 67.331418 n.a. n.a. 0.992801984780 0.4372623 0.00083038192782 1.3716423 101.5572 /T 78.3961 108.4/ 0.5554 n.a. n.a. 59.618057 9.7658592 66.429191 2024-Oct-31 20:00 22 09 48.85 -35 56 38.9 233.448084 65.609444 n.a. n.a. 0.992803722982 0.4338798 0.00083588342909 1.3732337 101.6515 /T 78.3015 108.4/ 0.5424 n.a. n.a. 59.924648 10.240475 66.206357 2024-Oct-31 20:10 22 09 57.78 -35 46 49.4 235.616124 63.823564 n.a. n.a. 0.992805447652 0.4304976 0.00084139125813 1.3747760 101.7475 /T 78.2052 108.4/ 0.5294 n.a. n.a. 60.220173 10.769300 65.986374 2024-Oct-31 20:20 22 10 07.20 -35 36 58.1 237.428025 61.986351 n.a. n.a. 0.992807158792 0.4271162 0.00084690515591 1.3762388 101.8452 /T 78.1072 108.4/ 0.5165 n.a. n.a. 60.504879 11.349203 65.768711 2024-Oct-31 20:30 22 10 17.17 -35 27 05.2 238.940706 60.107716 n.a. n.a. 0.992808856407 0.4237362 0.00085242474227 1.3775921 101.9448 /T 78.0073 108.5/ 0.5037 n.a. n.a. 60.779161 11.977135 65.552785 2024-Oct-31 20:40 22 10 27.72 -35 17 11.2 240.200934 58.195530 n.a. n.a. 0.992810540505 0.4203583 0.00085794951847 1.3788067 102.0463 /T 77.9055 108.5/ 0.4909 n.a. n.a. 61.043536 12.650131 65.337972 2024-Oct-31 20:50 22 10 38.88 -35 07 16.3 241.246975 56.256098 n.a. n.a. 0.992812211093 0.4169830 0.00086347886983 1.3798542 102.1498 /T 77.8017 108.5/ 0.4783 n.a. n.a. 61.298616 13.365302 65.123616 2024-Oct-31 21:00 22 10 50.68 -34 57 20.7 242.110126 54.294528 n.a. n.a. 0.992813868185 0.4136106 0.00086901206874 1.3807066 102.2555 /T 77.6958 108.5/ 0.4657 n.a. n.a. 61.545087 14.119827 64.909037 2024-Oct-31 21:10 22 11 03.17 -34 47 24.9 242.816028 52.314999 n.a. n.a. 0.992815511793 0.4102417 0.00087454827761 1.3813370 102.3632 /T 77.5877 108.5/ 0.4533 n.a. n.a. 61.783687 14.910948 64.693541 2024-Oct-31 21:20 22 11 16.37 -34 37 29.0 243.385746 50.320973 n.a. n.a. 0.992817141932 0.4068767 0.00088008655231 1.3817192 102.4733 /T 77.4774 108.6/ 0.4410 n.a. n.a. 62.015182 15.735970 64.476425 2024-Oct-31 21:30 22 11 30.30 -34 27 33.3 243.836651 48.315352 n.a. n.a. 0.992818758619 0.4035160 0.00088562584552 1.3818280 102.5855 /T 77.3648 108.6/ 0.4288 n.a. n.a. 62.240353 16.592252 64.256987 2024-Oct-31 21:40 22 11 44.99 -34 17 38.3 244.183121 46.300595 n.a. n.a. 0.992820361871 0.4001599 0.00089116501046 1.3816390 102.7002 /T 77.2499 108.6/ 0.4168 n.a. n.a. 62.459975 17.477210 64.034527 2024-Oct-31 21:50 22 12 00.45 -34 07 44.1 244.437096 44.278813 n.a. n.a. 0.992821951708 0.3968086 0.00089670280460 1.3811288 102.8171 /T 77.1327 108.7/ 0.4049 n.a. n.a. 62.674801 18.388310 63.808357 2024-Oct-31 22:00 22 12 16.71 -33 57 51.1 244.608532 42.251837 n.a. n.a. 0.992823528150 0.3934626 0.00090223789363 1.3802751 102.9365 /T 77.0130 108.7/ 0.3932 n.a. n.a. 62.885551 19.323071 63.577806 2024-Oct-31 22:10 22 12 33.79 -33 47 59.5 244.705773 40.221293 n.a. n.a. 0.992825091678 0.3903485 0.00090776939448 1.3793218 103.0583 /T 76.8909 108.7/ 0.3816 n.a. n.a. 63.109179 20.283679 63.340697 2024-Oct-31 22:20 22 12 51.70 -33 38 09.5 244.735810 38.188621 n.a. n.a. 0.992826642713 0.3872117 0.00091329626500 1.3779488 103.1825 /T 76.7664 108.8/ 0.3703 n.a. n.a. 63.327714 21.261973 63.098194 2024-Oct-31 22:30 22 13 10.45 -33 28 21.4 244.704479 36.155102 n.a. n.a. 0.992828181137 0.3840397 0.00091881675027 1.3761227 103.3092 /T 76.6394 108.8/ 0.3591 n.a. n.a. 63.540832 22.255530 62.849769 2024-Oct-31 22:40 22 13 30.05 -33 18 35.7 244.616672 34.121904 n.a. n.a. 0.992829706789 0.3808241 0.00092432897396 1.3738153 103.4384 /T 76.5100 108.8/ 0.3481 n.a. n.a. 63.748450 23.262124 62.594886 2024-Oct-31 22:50 22 13 50.50 -33 08 52.4 244.476491 32.090098 n.a. n.a. 0.992831219485 0.3775600 0.00092983095801 1.3710041 103.5700 /T 76.3781 108.9/ 0.3373 n.a. n.a. 63.950676 24.279687 62.333003 2024-Oct-31 23:00 22 14 11.81 -32 59 12.1 244.287362 30.060685 n.a. n.a. 0.992832719027 0.3742464 0.00093532064439 1.3676719 103.7041 /T 76.2437 108.9/ 0.3267 n.a. n.a. 64.147818 25.306298 62.063582 2024-Oct-31 23:10 22 14 33.97 -32 49 34.9 244.052139 28.034610 n.a. n.a. 0.992834205220 0.3708859 0.00094079591710 1.3638069 103.8405 /T 76.1070 109.0/ 0.3163 n.a. n.a. 64.340362 26.340147 61.786088 2024-Oct-31 23:20 22 14 56.99 -32 40 01.2 243.773178 26.012772 n.a. n.a. 0.992835677888 0.3674846 0.00094625462345 1.3594024 103.9793 /T 75.9679 109.0/ 0.3061 n.a. n.a. 64.528943 27.379518 61.500000 2024-Oct-31 23:30 22 15 20.86 -32 30 31.3 243.452406 23.996039 n.a. n.a. 0.992837136883 0.3640515 0.00095169459334 1.3544565 104.1205 /T 75.8265 109.1/ 0.2961 n.a. n.a. 64.714293 28.422756 61.204818 2024-Oct-31 23:40 22 15 45.58 -32 21 05.3 243.091375 21.985260 n.a. n.a. 0.992838582101 0.3605976 0.00095711365563 1.3489704 104.2639 /T 75.6828 109.1/ 0.2863 n.a. n.a. 64.897183 29.468250 60.900072 2024-Oct-31 23:50 22 16 11.13 -32 11 43.6 242.691303 19.981266 n.a. n.a. 0.992840013482 0.3571352 0.00096250965076 1.3429483 104.4096 /T 75.5368 109.2/ 0.2768 n.a. n.a. 65.078355 30.514417 60.585334 2024-Nov-01 00:00 22 16 37.53 -32 02 26.3 242.253112 17.984886 n.a. n.a. 0.992841431018 0.3536771 0.00096788043936 1.3363961 104.5575 /T 75.3887 109.2/ 0.2674 n.a. n.a. 65.258455 31.559691 60.260220 $$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 ***************************************************************************************************************************************************************************************************************************************************