API VERSION: 1.2 API SOURCE: NASA/JPL Horizons API ******************************************************************************* Revised: Dec 06, 2024 Gaia Observatory -139479 http://sci.esa.int/gaia/ BACKGROUND: Gaia is designed and operated by the European Space Agency. It launched December 19, 2013 @ 09:12 UTC on a Soyuz launcher from Kourou, French Guiana. On 2014-Jan-08, it arrived at its operational Lissajous orbit around the gravitationally stable Earth-Sun Lagrange-point L2, roughly 1.5 million km from Earth in the direction opposite the Sun. The orbit is not shadowed by Earth eclipses. The orbit period is about 180 days; the size of the orbit is typically 340,000 x 90,000 km. MISSION: Gaia's 5-year primary mission is to ... * Measure the positions of ~1 billion stars both in our Galaxy and other members of the Local Group, with an accuracy down to 24 uas * Perform spectral and photometric measurements of all objects * Derive space velocities of the Galaxy's constituent stars using the stellar distances and motions * Create a three-dimensional structural map of the Galaxy Additional expected results include extrasolar planet detection, brown dwarf detection, solar system asteroid discoveries, supernova early detection, and testing of Einstein's general relativity. GAIA SPACECRAFT: Spacecraft dry mass total 1392 kg Propellant 237 kg Total launch mass 2029 kg Power: 12.8 m^2 solar array provides up to 1910 Watts SCIENCE INSTRUMENTS: Single integrated instrument that comprises three major functions: astrometry, photometry (320-1000 nm) and spectrometry (846-874 nm). The three functions use two common telescopes and a shared focal plane, with each function having a dedicated area on the large 0.5m x 1m CCD detector array. SPACECRAFT TRAJECTORY (from ESA 2024-Dec-03, predicts thereafter) Trajectory name Start Stop -------------------------------------------- ----------- ----------- ORB1_20241203_000001 2013-Dec-19 2026-Sep-14 ******************************************************************************* ******************************************************************************* Ephemeris / API_USER Mon Dec 9 17:36:17 2024 Pasadena, USA / Horizons ******************************************************************************* Target body name: Gaia (spacecraft) (-139479) {source: gaia_merged} Center body name: Earth (399) {source: gaia_merged} Center-site name: iTelescope Obs., Siding Spring ******************************************************************************* Start time : A.D. 2024-Nov-30 00:00:00.0000 UT Stop time : A.D. 2024-Dec-01 00:00:00.0000 UT Step-size : 10 minutes ******************************************************************************* Target pole/equ : undefined Target radii : undefined Center geodetic : 149.0644, -31.2733577, 1.16499 {E-lon(deg),Lat(deg),Alt(km)} Center cylindric: 149.0644,5457.31536,-3292.4397 {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: gaia_merged} Rel. light bend : Sun {source: gaia_merged} 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.241209.p250307 EOP coverage : DATA-BASED 1962-JAN-20 TO 2024-DEC-09. PREDICTS-> 2025-MAR-06 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 .....< >..... Daylight Cut-off Requested .....< 2024-Nov-30 09:00 C 03 36 44.62 +20 27 51.3 56.664179 12.047925 n.a. n.a. 0.995616151487 -0.3194457 0.00959520545590 -0.3735926 168.4084 /T 11.4804 177.3/ 1.0117 n.a. n.a. 1.7817589 48.146166 -61.04904 2024-Nov-30 09:10 C 03 36 45.52 +20 28 03.1 55.086462 13.816850 n.a. n.a. 0.995614870383 -0.3193884 0.00959372339330 -0.3653345 168.4053 /T 11.4835 177.3/ 0.9958 n.a. n.a. 1.6695786 45.871264 -62.07662 2024-Nov-30 09:20 C 03 36 46.32 +20 28 14.6 53.456799 15.551758 n.a. n.a. 0.995613589508 -0.3193311 0.00959227566809 -0.3564730 168.4019 /T 11.4870 177.3/ 0.9799 n.a. n.a. 1.5612885 43.413521 -63.07573 2024-Nov-30 09:30 N 03 36 47.04 +20 28 25.8 51.772012 17.250063 n.a. n.a. 0.995612308864 -0.3192737 0.00959086466718 -0.3470248 168.3981 /T 11.4908 177.3/ 0.9640 n.a. n.a. 1.4571982 40.753062 -64.04156 2024-Nov-30 09:40 N 03 36 47.67 +20 28 36.7 50.028919 18.908995 n.a. n.a. 0.995611028450 -0.3192164 0.00958949270832 -0.3370078 168.3939 /T 11.4949 177.3/ 0.9480 n.a. n.a. 1.3576173 37.868388 -64.96839 2024-Nov-30 09:50 N 03 36 48.22 +20 28 47.2 48.224370 20.525590 n.a. n.a. 0.995609748265 -0.3191591 0.00958816203558 -0.3264408 168.3894 /T 11.4994 177.2/ 0.9319 n.a. n.a. 1.2628543 34.736692 -65.84942 2024-Nov-30 10:00 A 03 36 48.70 +20 28 57.5 46.355290 22.096688 n.a. n.a. 0.995608468311 -0.3191018 0.00958687481498 -0.3153438 168.3846 /T 11.5042 177.2/ 0.9159 n.a. n.a. 1.1732126 31.334459 -66.67656 2024-Nov-30 10:10 A 03 36 49.09 +20 29 07.3 44.418730 23.618928 n.a. n.a. 0.995607188587 -0.3190444 0.00958563313019 -0.3037380 168.3794 /T 11.5093 177.2/ 0.8998 n.a. n.a. 1.0889857 27.638452 -67.44022 2024-Nov-30 10:20 A 03 36 49.41 +20 29 16.8 42.411935 25.088746 n.a. n.a. 0.995605909092 -0.3189871 0.00958443897856 -0.2916452 168.3740 /T 11.5147 177.1/ 0.8837 n.a. n.a. 1.0104488 23.627217 -68.12910 2024-Nov-30 10:30 03 36 49.66 +20 29 25.8 40.332415 26.502381 n.a. n.a. 0.995604629828 -0.3189297 0.00958329426710 -0.2790886 168.3683 /T 11.5204 177.1/ 0.8677 n.a. n.a. 0.9378478 19.283155 -68.72998 2024-Nov-30 10:40 03 36 49.85 +20 29 34.5 38.178039 27.855884 n.a. n.a. 0.995603350794 -0.3188723 0.00958220080884 -0.2660919 168.3623 /T 11.5263 177.0/ 0.8516 n.a. n.a. 0.8713829 14.595209 -69.22754 2024-Nov-30 10:50 03 36 49.98 +20 29 42.7 35.947133 29.145134 n.a. n.a. 0.995602071990 -0.3188150 0.00958116031919 -0.2526800 168.3560 /T 11.5326 177.0/ 0.8356 n.a. n.a. 0.8111884 9.5619582 -69.60423 2024-Nov-30 11:00 03 36 50.04 +20 29 50.5 33.638590 30.365860 n.a. n.a. 0.995600793416 -0.3187576 0.00958017441265 -0.2388784 168.3495 /T 11.5390 176.9/ 0.8196 n.a. n.a. 0.7573085 4.1947122 -69.84016 2024-Nov-30 11:10 03 36 50.05 +20 29 57.8 31.251991 31.513675 n.a. n.a. 0.995599515072 -0.3187002 0.00957924459953 -0.2247135 168.3428 /T 11.5457 176.9/ 0.8037 n.a. n.a. 0.7096713 358.51988 -69.91310 2024-Nov-30 11:20 03 36 50.02 +20 30 04.7 28.787727 32.584114 n.a. n.a. 0.995598236959 -0.3186429 0.00957837228308 -0.2102123 168.3358 /T 11.5526 176.8/ 0.7879 n.a. n.a. 0.6680656 352.57969 -69.79829 2024-Nov-30 11:30 03 36 49.93 +20 30 11.0 26.247120 33.572690 n.a. n.a. 0.995596959075 -0.3185855 0.00957755875670 -0.1954026 168.3287 /T 11.5597 176.7/ 0.7721 n.a. n.a. 0.6321252 346.43030 -69.46800 2024-Nov-30 11:40 03 36 49.80 +20 30 16.9 23.632535 34.474953 n.a. n.a. 0.995595681422 -0.3185281 0.00957680520133 -0.1803126 168.3213 /T 11.5670 176.7/ 0.7565 n.a. n.a. 0.6013280 340.13708 -68.89050 2024-Nov-30 11:50 03 36 49.64 +20 30 22.3 20.947478 35.286564 n.a. n.a. 0.995594403999 -0.3184707 0.00957611268318 -0.1649713 168.3138 /T 11.5744 176.6/ 0.7409 n.a. n.a. 0.5750117 333.76731 -68.02780 2024-Nov-30 12:00 03 36 49.44 +20 30 27.2 18.196661 36.003371 n.a. n.a. 0.995593126807 -0.3184133 0.00957548215160 -0.1494080 168.3062 /T 11.5820 176.5/ 0.7255 n.a. n.a. 0.5524073 327.38171 -66.83169 2024-Nov-30 12:10 03 36 49.22 +20 30 31.6 15.386035 36.621499 n.a. n.a. 0.995591849844 -0.3183559 0.00957491443720 -0.1336526 168.2984 /T 11.5898 176.4/ 0.7101 n.a. n.a. 0.5326866 321.02658 -65.23682 2024-Nov-30 12:20 03 36 48.97 +20 30 35.5 12.522775 37.137441 n.a. n.a. 0.995590573113 -0.3182984 0.00957441025021 -0.1177352 168.2905 /T 11.5976 176.3/ 0.6950 n.a. n.a. 0.5150152 314.72765 -63.14929 2024-Nov-30 12:30 03 36 48.70 +20 30 38.9 9.615209 37.548142 n.a. n.a. 0.995589296611 -0.3182410 0.00957397017907 -0.1016864 168.2825 /T 11.6055 176.3/ 0.6799 n.a. n.a. 0.4986050 308.48660 -60.42771 2024-Nov-30 12:40 03 36 48.41 +20 30 41.7 6.672700 37.851083 n.a. n.a. 0.995588020340 -0.3181836 0.00957359468930 -0.0855369 168.2744 /T 11.6135 176.2/ 0.6651 n.a. n.a. 0.4827604 302.27959 -56.85129 2024-Nov-30 12:50 03 36 48.12 +20 30 44.0 3.705463 38.044358 n.a. n.a. 0.995586744299 -0.3181262 0.00957328412252 -0.0693178 168.2663 /T 11.6216 176.1/ 0.6504 n.a. n.a. 0.4669182 296.05713 -52.06590 2024-Nov-30 13:00 03 36 47.81 +20 30 45.8 0.724336 38.126725 n.a. n.a. 0.995585468489 -0.3180687 0.00957303869583 -0.0530601 168.2581 /T 11.6297 176.0/ 0.6358 n.a. n.a. 0.4506817 289.74423 -45.49701 2024-Nov-30 13:10 t 03 36 47.51 +20 30 47.0 357.740516 38.097651 n.a. n.a. 0.995584192909 -0.3180113 0.00957285850136 -0.0367950 168.2498 /T 11.6379 175.9/ 0.6215 n.a. n.a. 0.4338545 283.24019 -36.24162 2024-Nov-30 13:20 03 36 47.21 +20 30 47.8 354.765273 37.957325 n.a. n.a. 0.995582917559 -0.3179538 0.00957274350608 -0.0205538 168.2416 /T 11.6460 175.8/ 0.6073 n.a. n.a. 0.4164796 276.41832 -23.10251 2024-Nov-30 13:30 03 36 46.92 +20 30 48.0 351.809650 37.706654 n.a. n.a. 0.995581642440 -0.3178964 0.00957269355185 -0.0043676 168.2334 /T 11.6541 175.7/ 0.5934 n.a. n.a. 0.3988901 269.12700 -5.411014 2024-Nov-30 13:40 03 36 46.65 +20 30 47.6 348.884194 37.347231 n.a. n.a. 0.995580367552 -0.3178389 0.00957270835579 0.0117326 168.2252 /T 11.6622 175.6/ 0.5796 n.a. n.a. 0.3817731 261.19591 14.868292 2024-Nov-30 13:50 03 36 46.39 +20 30 46.8 345.998698 36.881291 n.a. n.a. 0.995579092894 -0.3177815 0.00957278751078 0.0277159 168.2171 /T 11.6703 175.5/ 0.5661 n.a. n.a. 0.3662419 252.45482 33.180413 2024-Nov-30 14:00 03 36 46.15 +20 30 45.4 343.162005 36.311643 n.a. n.a. 0.995577818467 -0.3177240 0.00957293048627 0.0435516 168.2090 /T 11.6783 175.4/ 0.5528 n.a. n.a. 0.3538901 242.77556 46.760250 2024-Nov-30 14:10 03 36 45.94 +20 30 43.5 340.381855 35.641589 n.a. n.a. 0.995576544270 -0.3176665 0.00957313662943 0.0592093 168.2010 /T 11.6862 175.3/ 0.5398 n.a. n.a. 0.3467650 232.14394 55.872189 2024-Nov-30 14:20 03 36 45.77 +20 30 41.1 337.664787 34.874840 n.a. n.a. 0.995575270304 -0.3176090 0.00957340516630 0.0746591 168.1932 /T 11.6940 175.2/ 0.5269 n.a. n.a. 0.3471705 220.74469 61.713585 2024-Nov-30 14:30 03 36 45.62 +20 30 38.3 335.016107 34.015425 n.a. n.a. 0.995573996568 -0.3175515 0.00957373520344 0.0898714 168.1854 /T 11.7017 175.1/ 0.5144 n.a. n.a. 0.3572546 208.99862 65.295456 2024-Nov-30 14:40 03 36 45.52 +20 30 34.9 332.439889 33.067605 n.a. n.a. 0.995572723064 -0.3174940 0.00957412572962 0.1048171 168.1778 /T 11.7092 175.0/ 0.5020 n.a. n.a. 0.3785069 197.47952 67.318697 2024-Nov-30 14:50 03 36 45.46 +20 30 31.0 329.939034 32.035786 n.a. n.a. 0.995571449789 -0.3174365 0.00957457561787 0.1194675 168.1703 /T 11.7166 174.9/ 0.4900 n.a. n.a. 0.4114531 186.72787 68.267429 2024-Nov-30 15:00 03 36 45.46 +20 30 26.7 327.515352 30.924447 n.a. n.a. 0.995570176746 -0.3173790 0.00957508362767 0.1337947 168.1630 /T 11.7239 174.8/ 0.4781 n.a. n.a. 0.4557334 177.08966 68.483393 2024-Nov-30 15:10 03 36 45.50 +20 30 21.9 325.169663 29.738069 n.a. n.a. 0.995568903933 -0.3173215 0.00957564840741 0.1477713 168.1559 /T 11.7309 174.7/ 0.4666 n.a. n.a. 0.5104470 168.67980 68.206848 2024-Nov-30 15:20 03 36 45.60 +20 30 16.7 322.901921 28.481083 n.a. n.a. 0.995567631351 -0.3172640 0.00957626849707 0.1613706 168.1490 /T 11.7377 174.6/ 0.4553 n.a. n.a. 0.5745088 161.44493 67.602810 2024-Nov-30 15:30 03 36 45.76 +20 30 11.1 320.711333 27.157821 n.a. n.a. 0.995566359000 -0.3172065 0.00957694233109 0.1745666 168.1423 /T 11.7444 174.5/ 0.4443 n.a. n.a. 0.6468748 155.24801 66.781904 2024-Nov-30 15:40 03 36 45.99 +20 30 05.0 318.596484 25.772477 n.a. n.a. 0.995565086880 -0.3171489 0.00957766824143 0.1873342 168.1358 /T 11.7508 174.3/ 0.4336 n.a. n.a. 0.7266351 149.92939 65.817149 2024-Nov-30 15:50 03 36 46.28 +20 29 58.5 316.555446 24.329086 n.a. n.a. 0.995563814990 -0.3170914 0.00957844446092 0.1996492 168.1296 /T 11.7569 174.2/ 0.4231 n.a. n.a. 0.8130285 145.33853 64.756468 2024-Nov-30 16:00 03 36 46.65 +20 29 51.6 314.585891 22.831501 n.a. n.a. 0.995562543331 -0.3170339 0.00957926912667 0.2114881 168.1236 /T 11.7628 174.1/ 0.4129 n.a. n.a. 0.9054234 141.34594 63.631372 2024-Nov-30 16:10 03 36 47.09 +20 29 44.4 312.685183 21.283380 n.a. n.a. 0.995561271904 -0.3169763 0.00958014028371 0.2228284 168.1180 /T 11.7684 174.0/ 0.4030 n.a. n.a. 1.0032900 137.84501 62.462727 2024-Nov-30 16:20 03 36 47.61 +20 29 36.8 310.850455 19.688181 n.a. n.a. 0.995560000707 -0.3169187 0.00958105588894 0.2336486 168.1126 /T 11.7737 173.9/ 0.3934 n.a. n.a. 1.1061745 134.74982 61.264471 2024-Nov-30 16:30 03 36 48.21 +20 29 28.8 309.078688 18.049161 n.a. n.a. 0.995558729740 -0.3168612 0.00958201381490 0.2439282 168.1075 /T 11.7787 173.8/ 0.3840 n.a. n.a. 1.2136785 131.99154 60.046022 2024-Nov-30 16:40 03 36 48.90 +20 29 20.6 307.366762 16.369376 n.a. n.a. 0.995557459005 -0.3168036 0.00958301185423 0.2536479 168.1027 /T 11.7834 173.7/ 0.3750 n.a. n.a. 1.3254428 129.51514 58.813802 2024-Nov-30 16:50 03 36 49.67 +20 29 12.0 305.711507 14.651688 n.a. n.a. 0.995556188501 -0.3167460 0.00958404772367 0.2627892 168.0983 /T 11.7878 173.6/ 0.3662 n.a. n.a. 1.4411363 127.27641 57.572239 2024-Nov-30 17:00 03 36 50.54 +20 29 03.2 304.109742 12.898769 n.a. n.a. 0.995554918228 -0.3166885 0.00958511906878 0.2713350 168.0942 /T 11.7919 173.5/ 0.3577 n.a. n.a. 1.5604471 125.23967 56.324411 2024-Nov-30 17:10 03 36 51.49 +20 28 54.1 302.558298 11.113115 n.a. n.a. 0.995553648185 -0.3166309 0.00958622346832 0.2792692 168.0904 /T 11.7956 173.4/ 0.3494 n.a. n.a. 1.6830767 123.37586 55.072476 2024-Nov-30 17:20 A 03 36 52.54 +20 28 44.7 301.054049 9.297047 n.a. n.a. 0.995552378374 -0.3165733 0.00958735843908 0.2865769 168.0870 /T 11.7989 173.3/ 0.3415 n.a. n.a. 1.8087359 121.66119 53.817955 2024-Nov-30 17:30 A 03 36 53.68 +20 28 35.2 299.593920 7.452730 n.a. n.a. 0.995551108794 -0.3165157 0.00958852144065 0.2932445 168.0840 /T 11.8019 173.2/ 0.3338 n.a. n.a. 1.9371414 120.07599 52.561925 2024-Nov-30 17:40 A 03 36 54.93 +20 28 25.4 298.174901 5.582176 n.a. n.a. 0.995549839444 -0.3164581 0.00958970988037 0.2992596 168.0813 /T 11.8046 173.1/ 0.3264 n.a. n.a. 2.0680140 118.60390 51.305152 2024-Nov-30 17:50 A 03 36 56.27 +20 28 15.4 296.794051 3.687259 n.a. n.a. 0.995548570326 -0.3164005 0.00959092111825 0.3046111 168.0791 /T 11.8068 173.0/ 0.3192 n.a. n.a. 2.2010771 117.23119 50.048180 2024-Nov-30 18:00 N 03 36 57.72 +20 28 05.3 295.448499 1.769724 n.a. n.a. 0.995547301439 -0.3163429 0.00959215247224 0.3092890 168.0772 /T 11.8087 172.9/ 0.3123 n.a. n.a. 2.3360555 115.94626 48.791394 2024-Nov-30 18:10 N 03 36 59.27 +20 27 55.1 294.135446 -0.168806 n.a. n.a. 0.995546032783 -0.3162853 0.00959340122317 0.3132847 168.0757 /T 11.8101 172.8/ 0.3057 n.a. n.a. 2.4726752 114.73926 47.535069 >..... Elevation Cut-off Requested .....< $$EOE *************************************************************************************************************************************************************************************************************************************************** Column meaning: TIME Times PRIOR to 1962 are UT1, a mean-solar time closely related to the prior but now-deprecated GMT. Times AFTER 1962 are in UTC, the current civil or "wall-clock" time-scale. UTC is kept within 0.9 seconds of UT1 using integer leap-seconds for 1972 and later years. Conversion from the internal Barycentric Dynamical Time (TDB) of solar system dynamics to the non-uniform civil UT time-scale requested for output has not been determined for UTC times after the next July or January 1st. Therefore, the last known leap-second is used as a constant over future intervals. Time tags refer to the UT time-scale conversion from TDB on Earth regardless of observer location within the solar system, although clock rates may differ due to the local gravity field and no analog to "UT" may be defined for that location. Any 'b' symbol in the 1st-column denotes a B.C. date. First-column blank (" ") denotes an A.D. date. CALENDAR SYSTEM Mixed calendar mode was active such that calendar dates after AD 1582-Oct-15 (if any) are in the modern Gregorian system. Dates prior to 1582-Oct-5 (if any) are in the Julian calendar system, which is automatically extended for dates prior to its adoption on 45-Jan-1 BC. The Julian calendar is useful for matching historical dates. The Gregorian calendar more accurately corresponds to the Earth's orbital motion and seasons. A "Gregorian-only" calendar mode is available if such physical events are the primary interest. NOTE: "n.a." in output means quantity "not available" at the print-time. SOLAR PRESENCE (OBSERVING SITE) Time tag is followed by a blank, then a solar-presence condition code: '*' Daylight (refracted solar upper-limb on or above apparent horizon) 'C' Civil twilight/dawn 'N' Nautical twilight/dawn 'A' Astronomical twilight/dawn ' ' Night OR geocentric ephemeris LUNAR PRESENCE WITH TARGET RISE/TRANSIT/SET EVENT MARKER (OBSERVING SITE) The solar-presence code column is immediately followed by another marker: 'm' Refracted upper-limb of Moon on or above apparent horizon ' ' Refracted upper-limb of Moon below apparent horizon OR geocentric The lunar presence marker (an ongoing state) can be over-ridden by a target event marker if an event has occurred since the last output step: 'r' Rise (target body on or went above cut-off RTS elevation) 'e' Elevation max (target body maximum elevation angle has occurred) 't' Transit (target body at or passed through observer meridian) 's' Set (target body on or went below cut-off RTS elevation) RTS MARKERS (TVH) Rise and set are with respect to the reference ellipsoid true visual horizon defined by the elevation cut-off angle. Horizon dip and yellow-light refraction (Earth only) are considered. Accuracy is < or = to twice the requested search step-size. 'R.A._____(ICRF)_____DEC' = Astrometric right ascension and declination of the target center with respect to the observing site (coordinate origin) in the reference frame of the planetary ephemeris (ICRF). Compensated for down-leg light-time delay aberration. Units: RA in hours-minutes-seconds of time, HH MM SS.ff{ffff} DEC in degrees-minutes-seconds of arc, sDD MN SC.f{ffff} 'Azi____(a-app)___Elev' = Airless apparent azimuth and elevation of target center. Compensated for light-time, the gravitational deflection of light, stellar aberration, precession and nutation. Azimuth is measured clockwise from north: North(0) -> East(90) -> South(180) -> West(270) -> North (360) Elevation angle is with respect to a plane perpendicular to the reference surface local zenith direction. TOPOCENTRIC ONLY. Units: DEGREES 'APmag S-brt' = The targets' approximate apparent visual magnitude and surface brightness. For planets and natural satellites, output is restricted to solar phase angles covered by observational data. Outside the observed phase angle range, "n.a." may be output to avoid extrapolation beyond the limit of model validity. For Earth-based observers, the estimated dimming due to atmospheric absorption (extinction) is available as a separate, requestable quantity. Surface brightness is the average airless visual magnitude of a square-arcsecond of the illuminated portion of the apparent disk. It is computed only if the target radius is known. Units: MAGNITUDES & MAGNITUDES PER SQUARE ARCSECOND 'r rdot' = The Sun's apparent range ("r", light-time aberrated) and range-rate ("rdot") relative to the target center, as seen by the observer. A positive "rdot" means the target center was moving away from the Sun, negative means moving toward the Sun. Units: AU and KM/S 'delta deldot' = Apparent range ("delta", light-time aberrated) and range-rate ("delta-dot") of the target center relative to the observer. A positive "deldot" means the target center is moving away from the observer, negative indicates movement toward the observer. Units: AU and KM/S 'S-O-T /r' = Sun-Observer-Target apparent SOLAR ELONGATION ANGLE seen from the observers' location at print-time. The '/r' column provides a code indicating the targets' apparent position relative to the Sun in the observers' sky, as described below: Case A: For an observing location on the surface of a rotating body, that body rotational sense is considered: /T indicates target TRAILS Sun (evening sky: rises and sets AFTER Sun) /L indicates target LEADS Sun (morning sky: rises and sets BEFORE Sun) Case B: For an observing point that does not have a rotational model (such as a spacecraft), the "leading" and "trailing" condition is defined by the observers' heliocentric ORBITAL motion: * If continuing in the observers' current direction of heliocentric motion would encounter the targets' apparent longitude first, followed by the Sun's, the target LEADS the Sun as seen by the observer. * If the Sun's apparent longitude would be encountered first, followed by the targets', the target TRAILS the Sun. Two other codes can be output: /* indicates observer is Sun-centered (undefined) /? Target is aligned with Sun center (no lead or trail) The S-O-T solar elongation angle is numerically the minimum separation angle of the Sun and target in the sky in any direction. It does NOT indicate the amount of separation in the leading or trailing directions, which would be defined along the equator of a spherical coordinate system. Units: DEGREES 'S-T-O' = The Sun-Target-Observer angle; the interior vertex angle at target center formed by a vector from the target to the apparent center of the Sun (at reflection time on the target) and the apparent vector from target to the observer at print-time. Slightly different from true PHASE ANGLE (requestable separately) at the few arcsecond level in that it includes stellar aberration on the down-leg from target to observer. Units: DEGREES 'T-O-M/MN_Illu%' = Target-Observer-Moon LUNAR ELONGATION angle and illuminated percentage. The apparent lunar elongation angle between target body center and Moon center, seen from the observing site, along with fraction of the lunar disk illuminated by the Sun. A negative lunar elongation angle indicates the target center is behind the Moon. Units: DEGREES & PERCENT 'RA_3sigma DEC_3sigma' = Uncertainty in Right-Ascension and Declination. Output values are the formal +/- 3 standard-deviations (sigmas) around nominal position. Units: ARCSECONDS 'Sky_motion Sky_mot_PA RelVel-ANG' = Total apparent angular rate of the target in the plane-of-sky. "Sky_mot_PA" is the position angle of the target's direction of motion in the plane-of-sky, measured counter-clockwise from the apparent of-date north pole direction. "RelVel-ANG" is the flight path angle of the target's relative motion with respect to the observer's line-of-sight, in the range [-90,+90], where positive values indicate motion away from the observer, negative values are toward the observer: -90 = target is moving directly toward the observer 0 = target is moving at right angles to the observer's line-of-sight +90 = target is moving directly away from the observer UNITS: ARCSECONDS/MINUTE, DEGREES, DEGREES Computations by ... Solar System Dynamics Group, Horizons On-Line Ephemeris System 4800 Oak Grove Drive, Jet Propulsion Laboratory Pasadena, CA 91109 USA General site: https://ssd.jpl.nasa.gov/ Mailing list: https://ssd.jpl.nasa.gov/email_list.html System news : https://ssd.jpl.nasa.gov/horizons/news.html User Guide : https://ssd.jpl.nasa.gov/horizons/manual.html Connect : browser https://ssd.jpl.nasa.gov/horizons/app.html#/x API https://ssd-api.jpl.nasa.gov/doc/horizons.html command-line telnet ssd.jpl.nasa.gov 6775 e-mail/batch https://ssd.jpl.nasa.gov/ftp/ssd/hrzn_batch.txt scripts https://ssd.jpl.nasa.gov/ftp/ssd/SCRIPTS Author : Jon.D.Giorgini@jpl.nasa.gov ***************************************************************************************************************************************************************************************************************************************************