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 19:09:31 2024 Pasadena, USA / Horizons ******************************************************************************* Target body name: Gaia (spacecraft) (-139479) {source: gaia_merged} Center body name: Earth (399) {source: gaia_merged} Center-site name: Swan Reach Imaging, Glenalta ******************************************************************************* 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 : 139.5701, -34.5440227, .056888 {E-lon(deg),Lat(deg),Alt(km)} Center cylindric: 139.5701,5259.32258,-3596.34777 {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 09:50 C 03 36 52.07 +20 28 46.5 54.128002 12.260151 n.a. n.a. 0.995609748272 -0.3191591 0.00959405153432 -0.3521045 168.4043 /T 11.4846 177.2/ 0.9409 n.a. n.a. 1.6710425 47.908140 -61.17109 2024-Nov-30 10:00 C 03 36 52.91 +20 28 57.6 52.419498 13.910678 n.a. n.a. 0.995608468317 -0.3191018 0.00959265646610 -0.3434498 168.4009 /T 11.4879 177.2/ 0.9256 n.a. n.a. 1.5644878 45.712492 -62.15601 2024-Nov-30 10:10 N 03 36 53.66 +20 29 08.4 50.660582 15.523385 n.a. n.a. 0.995607188593 -0.3190444 0.00959129724262 -0.3342333 168.3972 /T 11.4916 177.2/ 0.9102 n.a. n.a. 1.4616488 43.350938 -63.11340 2024-Nov-30 10:20 N 03 36 54.34 +20 29 18.9 48.848574 17.095579 n.a. n.a. 0.995605909098 -0.3189871 0.00958997608292 -0.3244724 168.3932 /T 11.4956 177.1/ 0.8947 n.a. n.a. 1.3627682 40.806653 -64.03917 2024-Nov-30 10:30 N 03 36 54.93 +20 29 29.1 46.980882 18.624407 n.a. n.a. 0.995604629834 -0.3189297 0.00958869513406 -0.3141854 168.3889 /T 11.4999 177.1/ 0.8793 n.a. n.a. 1.2680814 38.061500 -64.92853 2024-Nov-30 10:40 N 03 36 55.45 +20 29 38.9 45.055047 20.106856 n.a. n.a. 0.995603350799 -0.3188723 0.00958745646714 -0.3033918 168.3842 /T 11.5046 177.1/ 0.8638 n.a. n.a. 1.1778133 35.096242 -65.77586 2024-Nov-30 10:50 A 03 36 55.89 +20 29 48.4 43.068791 21.539751 n.a. n.a. 0.995602071995 -0.3188150 0.00958626207307 -0.2921122 168.3792 /T 11.5095 177.0/ 0.8484 n.a. n.a. 1.0921751 31.890905 -66.57458 2024-Nov-30 11:00 A 03 36 56.27 +20 29 57.4 41.020073 22.919766 n.a. n.a. 0.995600793421 -0.3187576 0.00958511385881 -0.2803680 168.3740 /T 11.5147 177.0/ 0.8329 n.a. n.a. 1.0113597 28.425388 -67.31699 2024-Nov-30 11:10 A 03 36 56.58 +20 30 06.2 38.907155 24.243426 n.a. n.a. 0.995599515077 -0.3187002 0.00958401364356 -0.2681814 168.3685 /T 11.5202 176.9/ 0.8175 n.a. n.a. 0.9355357 24.680353 -67.99407 2024-Nov-30 11:20 A 03 36 56.82 +20 30 14.5 36.728672 25.507123 n.a. n.a. 0.995598236963 -0.3186429 0.00958296315525 -0.2555756 168.3627 /T 11.5259 176.9/ 0.8020 n.a. n.a. 0.8648388 20.638454 -68.59536 2024-Nov-30 11:30 03 36 57.01 +20 30 22.3 34.483716 26.707137 n.a. n.a. 0.995596959080 -0.3185855 0.00958196402713 -0.2425747 168.3567 /T 11.5319 176.8/ 0.7867 n.a. n.a. 0.7993619 16.285896 -69.10870 2024-Nov-30 11:40 03 36 57.14 +20 30 29.8 32.171915 27.839658 n.a. n.a. 0.995595681427 -0.3185281 0.00958101779458 -0.2292035 168.3504 /T 11.5382 176.7/ 0.7713 n.a. n.a. 0.7391428 11.614250 -69.52003 2024-Nov-30 11:50 03 36 57.22 +20 30 36.8 29.793523 28.900820 n.a. n.a. 0.995594404004 -0.3184707 0.00958012589204 -0.2154874 168.3439 /T 11.5446 176.7/ 0.7561 n.a. n.a. 0.6841503 6.6223098 -69.81317 2024-Nov-30 12:00 03 36 57.25 +20 30 43.4 27.349502 29.886738 n.a. n.a. 0.995593126811 -0.3184133 0.00957928965027 -0.2014527 168.3372 /T 11.5512 176.6/ 0.7409 n.a. n.a. 0.6342701 1.3176124 -69.96939 2024-Nov-30 12:10 03 36 57.24 +20 30 49.5 24.841604 30.793555 n.a. n.a. 0.995591849848 -0.3183559 0.00957851029362 -0.1871262 168.3303 /T 11.5581 176.5/ 0.7258 n.a. n.a. 0.5892932 355.71711 -69.96689 2024-Nov-30 12:20 03 36 57.19 +20 30 55.2 22.272437 31.617498 n.a. n.a. 0.995590573116 -0.3182984 0.00957778893776 -0.1725353 168.3233 /T 11.5651 176.4/ 0.7108 n.a. n.a. 0.5489077 349.84639 -69.77976 2024-Nov-30 12:30 03 36 57.10 +20 31 00.3 19.645519 32.354933 n.a. n.a. 0.995589296614 -0.3182410 0.00957712658733 -0.1577079 168.3161 /T 11.5722 176.4/ 0.6959 n.a. n.a. 0.5127000 343.73698 -69.37611 2024-Nov-30 12:40 03 36 56.98 +20 31 05.0 16.965300 33.002432 n.a. n.a. 0.995588020343 -0.3181836 0.00957652413407 -0.1426724 168.3087 /T 11.5795 176.3/ 0.6812 n.a. n.a. 0.4801654 337.42150 -68.71473 2024-Nov-30 12:50 03 36 56.84 +20 31 09.2 14.237171 33.556837 n.a. n.a. 0.995586744302 -0.3181262 0.00957598235502 -0.1274576 168.3012 /T 11.5869 176.2/ 0.6665 n.a. n.a. 0.4507310 330.92710 -67.73898 2024-Nov-30 13:00 03 36 56.67 +20 31 12.9 11.467421 34.015330 n.a. n.a. 0.995585468491 -0.3180687 0.00957550191100 -0.1120927 168.2936 /T 11.5944 176.1/ 0.6520 n.a. n.a. 0.4237901 324.26747 -66.36583 2024-Nov-30 13:10 03 36 56.49 +20 31 16.0 8.663171 34.375496 n.a. n.a. 0.995584192911 -0.3180113 0.00957508334526 -0.0966070 168.2860 /T 11.6021 176.0/ 0.6376 n.a. n.a. 0.3987457 317.43456 -64.46550 2024-Nov-30 13:20 03 36 56.29 +20 31 18.7 5.832264 34.635383 n.a. n.a. 0.995582917561 -0.3179538 0.00957472708248 -0.0810303 168.2782 /T 11.6097 175.9/ 0.6234 n.a. n.a. 0.3750608 310.39020 -61.82237 2024-Nov-30 13:30 03 36 56.08 +20 31 20.9 2.983124 34.793549 n.a. n.a. 0.995581642442 -0.3178964 0.00957443342784 -0.0653925 168.2704 /T 11.6175 175.8/ 0.6094 n.a. n.a. 0.3523163 303.05784 -58.05577 2024-Nov-30 13:40 03 36 55.87 +20 31 22.5 0.124585 34.849106 n.a. n.a. 0.995580367554 -0.3178389 0.00957420256650 -0.0497235 168.2626 /T 11.6253 175.7/ 0.5955 n.a. n.a. 0.3302752 295.31450 -52.45161 2024-Nov-30 13:50 t 03 36 55.66 +20 31 23.7 357.265691 34.801738 n.a. n.a. 0.995579092895 -0.3177815 0.00957403456318 -0.0340534 168.2547 /T 11.6331 175.7/ 0.5819 n.a. n.a. 0.3089629 286.98391 -43.60540 2024-Nov-30 14:00 03 36 55.45 +20 31 24.3 354.415498 34.651713 n.a. n.a. 0.995577818468 -0.3177240 0.00957392936205 -0.0184123 168.2468 /T 11.6408 175.6/ 0.5684 n.a. n.a. 0.2887677 277.83529 -28.85709 2024-Nov-30 14:10 03 36 55.25 +20 31 24.5 351.582863 34.399878 n.a. n.a. 0.995576544271 -0.3176665 0.00957388678685 -0.0028301 168.2390 /T 11.6486 175.5/ 0.5551 n.a. n.a. 0.2705666 267.60070 -5.170108 2024-Nov-30 14:20 03 36 55.07 +20 31 24.1 348.776248 34.047630 n.a. n.a. 0.995575270304 -0.3176090 0.00957390654127 0.0126633 168.2311 /T 11.6564 175.4/ 0.5420 n.a. n.a. 0.2558502 256.03786 23.150810 2024-Nov-30 14:30 03 36 54.90 +20 31 23.2 346.003548 33.596882 n.a. n.a. 0.995573996569 -0.3175515 0.00957398820943 0.0280382 168.2234 /T 11.6641 175.3/ 0.5292 n.a. n.a. 0.2467549 243.07162 44.472289 2024-Nov-30 14:40 03 36 54.76 +20 31 21.9 343.271948 33.050015 n.a. n.a. 0.995572723064 -0.3174940 0.00957413125686 0.0432651 168.2156 /T 11.6717 175.1/ 0.5165 n.a. n.a. 0.2458179 228.99649 56.671837 2024-Nov-30 14:50 03 36 54.64 +20 31 20.0 340.587806 32.409819 n.a. n.a. 0.995571449789 -0.3174365 0.00957433503138 0.0583149 168.2080 /T 11.6793 175.0/ 0.5041 n.a. n.a. 0.2553272 214.57444 63.126493 2024-Nov-30 15:00 03 36 54.55 +20 31 17.7 337.956583 31.679425 n.a. n.a. 0.995570176746 -0.3173790 0.00957459876455 0.0731586 168.2005 /T 11.6867 174.9/ 0.4919 n.a. n.a. 0.2765395 200.80474 66.370927 2024-Nov-30 15:10 03 36 54.50 +20 31 14.8 335.382808 30.862242 n.a. n.a. 0.995568903933 -0.3173215 0.00957492157308 0.0877680 168.1931 /T 11.6941 174.8/ 0.4800 n.a. n.a. 0.3093892 188.47437 67.804564 2024-Nov-30 15:20 03 36 54.49 +20 31 11.5 332.870072 29.961892 n.a. n.a. 0.995567631350 -0.3172640 0.00957530246063 0.1021151 168.1858 /T 11.7013 174.7/ 0.4683 n.a. n.a. 0.3528864 177.90654 68.199044 2024-Nov-30 15:30 03 36 54.52 +20 31 07.8 330.421052 28.982139 n.a. n.a. 0.995566358999 -0.3172065 0.00957574031975 0.1161723 168.1787 /T 11.7083 174.6/ 0.4569 n.a. n.a. 0.4057323 169.04331 67.988561 2024-Nov-30 15:40 03 36 54.60 +20 31 03.6 328.037568 27.926834 n.a. n.a. 0.995565086878 -0.3171489 0.00957623393409 0.1299129 168.1717 /T 11.7152 174.5/ 0.4457 n.a. n.a. 0.4667190 161.64691 67.419607 2024-Nov-30 15:50 03 36 54.73 +20 30 58.9 325.720643 26.799862 n.a. n.a. 0.995563814989 -0.3170914 0.00957678198079 0.1433106 168.1650 /T 11.7219 174.4/ 0.4347 n.a. n.a. 0.5348655 155.44465 66.633373 2024-Nov-30 16:00 03 36 54.92 +20 30 53.9 323.470582 25.605093 n.a. n.a. 0.995562543330 -0.3170339 0.00957738303308 0.1563399 168.1584 /T 11.7284 174.3/ 0.4240 n.a. n.a. 0.6094133 150.19337 65.711963 2024-Nov-30 16:10 03 36 55.17 +20 30 48.4 321.287063 24.346341 n.a. n.a. 0.995561271901 -0.3169763 0.00957803556310 0.1689758 168.1520 /T 11.7347 174.2/ 0.4136 n.a. n.a. 0.6897771 145.69628 64.704139 2024-Nov-30 16:20 03 36 55.48 +20 30 42.5 319.169216 23.027336 n.a. n.a. 0.995560000704 -0.3169187 0.00957873794490 0.1811944 168.1459 /T 11.7407 174.1/ 0.4035 n.a. n.a. 0.7754950 141.80033 63.639544 2024-Nov-30 16:30 03 36 55.85 +20 30 36.2 317.115710 21.651695 n.a. n.a. 0.995558729738 -0.3168612 0.00957948845756 0.1929724 168.1400 /T 11.7465 174.0/ 0.3936 n.a. n.a. 0.8661882 138.38806 62.536667 2024-Nov-30 16:40 03 36 56.30 +20 30 29.6 315.124836 20.222902 n.a. n.a. 0.995557459002 -0.3168036 0.00958028528875 0.2042874 168.1344 /T 11.7521 173.9/ 0.3840 n.a. n.a. 0.9615335 135.36931 61.407308 2024-Nov-30 16:50 03 36 56.82 +20 30 22.6 313.194575 18.744298 n.a. n.a. 0.995556188498 -0.3167460 0.00958112653805 0.2151180 168.1290 /T 11.7574 173.8/ 0.3746 n.a. n.a. 1.0612433 132.67445 60.259196 2024-Nov-30 17:00 03 36 57.41 +20 30 15.2 311.322667 17.219069 n.a. n.a. 0.995554918224 -0.3166885 0.00958201022086 0.2254435 168.1240 /T 11.7624 173.7/ 0.3655 n.a. n.a. 1.1650528 130.24918 59.097492 2024-Nov-30 17:10 03 36 58.09 +20 30 07.5 309.506664 15.650240 n.a. n.a. 0.995553648182 -0.3166309 0.00958293427217 0.2352445 168.1192 /T 11.7672 173.6/ 0.3567 n.a. n.a. 1.2727111 128.05068 57.925728 2024-Nov-30 17:20 03 36 58.84 +20 29 59.6 307.743988 14.040678 n.a. n.a. 0.995552378370 -0.3165733 0.00958389655063 0.2445024 168.1147 /T 11.7716 173.5/ 0.3482 n.a. n.a. 1.3839753 126.04481 56.746365 2024-Nov-30 17:30 03 36 59.68 +20 29 51.3 306.031962 12.393087 n.a. n.a. 0.995551108790 -0.3165157 0.00958489484274 0.2531998 168.1105 /T 11.7757 173.4/ 0.3399 n.a. n.a. 1.4986068 124.20402 55.561155 2024-Nov-30 17:40 A 03 37 00.61 +20 29 42.8 304.367852 10.710019 n.a. n.a. 0.995549839440 -0.3164581 0.00958592686715 0.2613203 168.1067 /T 11.7795 173.3/ 0.3319 n.a. n.a. 1.6163683 122.50588 54.371363 2024-Nov-30 17:50 A 03 37 01.63 +20 29 34.0 302.748890 8.993871 n.a. n.a. 0.995548570322 -0.3164005 0.00958699027905 0.2688487 168.1032 /T 11.7829 173.2/ 0.3241 n.a. n.a. 1.7370225 120.93189 53.177928 2024-Nov-30 18:00 A 03 37 02.73 +20 29 25.0 301.172297 7.246897 n.a. n.a. 0.995547301434 -0.3163429 0.00958808267481 0.2757708 168.1000 /T 11.7861 173.1/ 0.3167 n.a. n.a. 1.8603308 119.46670 51.981549 2024-Nov-30 18:10 A 03 37 03.93 +20 29 15.8 299.635299 5.471212 n.a. n.a. 0.995546032778 -0.3162853 0.00958920159650 0.2820738 168.0972 /T 11.7888 173.0/ 0.3094 n.a. n.a. 1.9860527 118.09743 50.782764 2024-Nov-30 18:20 N 03 37 05.23 +20 29 06.4 298.135135 3.668803 n.a. n.a. 0.995544764353 -0.3162277 0.00959034453685 0.2877458 168.0948 /T 11.7912 172.9/ 0.3025 n.a. n.a. 2.1139456 116.81317 49.581990 2024-Nov-30 18:30 N 03 37 06.62 +20 28 56.8 296.669070 1.841531 n.a. n.a. 0.995543496159 -0.3161700 0.00959150894383 0.2927765 168.0927 /T 11.7933 172.8/ 0.2958 n.a. n.a. 2.2437646 115.60466 48.379555 2024-Nov-30 18:40 N 03 37 08.11 +20 28 47.1 295.234392 -0.008854 n.a. n.a. 0.995542228196 -0.3161124 0.00959269222584 0.2971564 168.0910 /T 11.7949 172.7/ 0.2894 n.a. n.a. 2.3752627 114.46393 47.175724 >..... 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 ***************************************************************************************************************************************************************************************************************************************************