API VERSION: 1.2 API SOURCE: NASA/JPL Horizons API ******************************************************************************* Revised: May 16, 2025 Gaia Observatory -139479 http://sci.esa.int/gaia/ https://www.cosmos.esa.int/web/gaia/iow_20250327 https://www.youtube.com/watch?v=8RznHsG12t0 NOTE: Science observations ended 2025-Jan-25 due to decreasing attitude control propellant. On March 28, 2025, after engineering tests, Gaia left its orbit around Earth-Sun L2 and was placed in a heliocentric disposal orbit. It will return to the Earth's vicinity every 14 years, but at a distance of ~10 million km. 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 ESOC 2025-Apr-14 16:41. Final reconstruction through 2025-Mar-28 end-of-mission, with 100 year prediction): Trajectory name Start Stop -------------------------------------------- ----------- ----------- ORB1_20250414_000001 2013-Dec-19 2125-Mar-28 ******************************************************************************* ******************************************************************************* Ephemeris / API_USER Thu Jul 10 01:12:57 2025 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-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 : 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.250709.p251005 EOP coverage : DATA-BASED 1962-JAN-20 TO 2025-JUL-09. PREDICTS-> 2025-OCT-04 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-Oct-31 09:20 C 01 34 40.28 +15 59 31.5 61.735890 10.728396 n.a. n.a. 1.002910732633 -0.4967232 0.01040093614292 -0.3656960 168.2262 /T 11.6525 174.8/ 1.3630 n.a. n.a. 1.2941583 17.734289 -66.01383 2024-Oct-31 09:30 C 01 34 40.52 +15 59 43.7 60.105732 12.530033 n.a. n.a. 1.002908740439 -0.4967019 0.01039948385781 -0.3583813 168.2206 /T 11.6580 174.9/ 1.3454 n.a. n.a. 1.2469752 12.766462 -66.37518 2024-Oct-31 09:40 N 01 34 40.67 +15 59 55.8 58.430261 14.302218 n.a. n.a. 1.002906748331 -0.4966806 0.01039806215918 -0.3504464 168.2146 /T 11.6639 174.9/ 1.3277 n.a. n.a. 1.2087774 7.5877708 -66.56104 2024-Oct-31 09:50 N 01 34 40.74 +16 00 07.7 56.706038 16.042553 n.a. n.a. 1.002904756309 -0.4966593 0.01039667350495 -0.3419063 168.2084 /T 11.6701 175.0/ 1.3098 n.a. n.a. 1.1797462 2.2641642 -66.55636 2024-Oct-31 10:00 N 01 34 40.73 +16 00 19.4 54.929587 17.748472 n.a. n.a. 1.002902764372 -0.4966379 0.01039532029068 -0.3327771 168.2019 /T 11.6766 175.0/ 1.2919 n.a. n.a. 1.1598059 356.87432 -66.34896 2024-Oct-31 10:10 A 01 34 40.65 +16 00 30.8 53.097425 19.417227 n.a. n.a. 1.002900772521 -0.4966166 0.01039400484486 -0.3230760 168.1951 /T 11.6833 175.1/ 1.2739 n.a. n.a. 1.1486053 351.50293 -65.93034 2024-Oct-31 10:20 A 01 34 40.49 +16 00 42.1 51.206079 21.045878 n.a. n.a. 1.002898780756 -0.4965952 0.01039272942438 -0.3128216 168.1880 /T 11.6904 175.1/ 1.2558 n.a. n.a. 1.1455286 346.23263 -65.29592 2024-Oct-31 10:30 A 01 34 40.27 +16 00 53.1 49.252138 22.631287 n.a. n.a. 1.002896789076 -0.4965738 0.01039149621013 -0.3020332 168.1806 /T 11.6977 175.1/ 1.2377 n.a. n.a. 1.1497352 341.13639 -64.44483 2024-Oct-31 10:40 A 01 34 39.98 +16 01 03.8 47.232289 24.170111 n.a. n.a. 1.002894797483 -0.4965525 0.01039030730279 -0.2907315 168.1729 /T 11.7053 175.2/ 1.2195 n.a. n.a. 1.1602213 336.27203 -63.37920 2024-Oct-31 10:50 01 34 39.62 +16 01 14.3 45.143387 25.658799 n.a. n.a. 1.002892805975 -0.4965311 0.01038916471860 -0.2789378 168.1650 /T 11.7131 175.2/ 1.2013 n.a. n.a. 1.1758880 331.67966 -62.10316 2024-Oct-31 11:00 01 34 39.20 +16 01 24.5 42.982525 27.093597 n.a. n.a. 1.002890814553 -0.4965097 0.01038807038560 -0.2666748 168.1569 /T 11.7212 175.2/ 1.1830 n.a. n.a. 1.1956068 327.38199 -60.62176 2024-Oct-31 11:10 01 34 38.73 +16 01 34.4 40.747121 28.470547 n.a. n.a. 1.002888823217 -0.4964883 0.01038702613959 -0.2539659 168.1485 /T 11.7295 175.3/ 1.1647 n.a. n.a. 1.2182729 323.38658 -58.94002 2024-Oct-31 11:20 01 34 38.19 +16 01 44.1 38.435018 29.785504 n.a. n.a. 1.002886831967 -0.4964668 0.01038603372081 -0.2408353 168.1400 /T 11.7380 175.3/ 1.1464 n.a. n.a. 1.2428425 319.68916 -57.06212 2024-Oct-31 11:30 01 34 37.61 +16 01 53.4 36.044596 31.034157 n.a. n.a. 1.002884840802 -0.4964454 0.01038509477030 -0.2273082 168.1312 /T 11.7467 175.3/ 1.1281 n.a. n.a. 1.2683560 316.27706 -54.99085 2024-Oct-31 11:40 01 34 36.98 +16 02 02.4 33.574897 32.212052 n.a. n.a. 1.002882849725 -0.4964240 0.01038421082679 -0.2134105 168.1222 /T 11.7556 175.4/ 1.1098 n.a. n.a. 1.2939487 313.13228 -52.72724 2024-Oct-31 11:50 01 34 36.30 +16 02 11.1 31.025755 33.314634 n.a. n.a. 1.002880858733 -0.4964025 0.01038338332365 -0.1991687 168.1131 /T 11.7646 175.4/ 1.0916 n.a. n.a. 1.3188525 310.23394 -50.27047 2024-Oct-31 12:00 01 34 35.58 +16 02 19.4 28.397927 34.337296 n.a. n.a. 1.002878867827 -0.4963810 0.01038261358608 -0.1846103 168.1038 /T 11.7738 175.4/ 1.0733 n.a. n.a. 1.3423926 307.56003 -47.61779 2024-Oct-31 12:10 01 34 34.82 +16 02 27.4 25.693223 35.275433 n.a. n.a. 1.002876877007 -0.4963596 0.01038190282842 -0.1697631 168.0944 /T 11.7831 175.4/ 1.0552 n.a. n.a. 1.3639803 305.08865 -44.76468 2024-Oct-31 12:20 01 34 34.03 +16 02 35.0 22.914616 36.124521 n.a. n.a. 1.002874886274 -0.4963381 0.01038125215190 -0.1546556 168.0849 /T 11.7926 175.5/ 1.0371 n.a. n.a. 1.3831052 302.79877 -41.70509 2024-Oct-31 12:30 01 34 33.21 +16 02 42.4 20.066333 36.880190 n.a. n.a. 1.002872895627 -0.4963166 0.01038066254228 -0.1393170 168.0752 /T 11.8022 175.5/ 1.0190 n.a. n.a. 1.3993264 300.67062 -38.43179 2024-Oct-31 12:40 01 34 32.36 +16 02 49.3 17.153908 37.538314 n.a. n.a. 1.002870905067 -0.4962951 0.01038013486807 -0.1237765 168.0654 /T 11.8118 175.5/ 1.0010 n.a. n.a. 1.4122650 298.68589 -34.93693 2024-Oct-31 12:50 01 34 31.49 +16 02 55.9 14.184192 38.095109 n.a. n.a. 1.002868914592 -0.4962736 0.01037966987870 -0.1080642 168.0556 /T 11.8216 175.5/ 0.9832 n.a. n.a. 1.4215968 296.82775 -31.21275 2024-Oct-31 13:00 01 34 30.60 +16 03 02.1 11.165303 38.547221 n.a. n.a. 1.002866924205 -0.4962520 0.01037926820311 -0.0922102 168.0457 /T 11.8314 175.5/ 0.9654 n.a. n.a. 1.4270455 295.08078 -27.25248 2024-Oct-31 13:10 01 34 29.70 +16 03 08.0 8.106524 38.891821 n.a. n.a. 1.002864933903 -0.4962305 0.01037893034848 -0.0762450 168.0358 /T 11.8412 175.5/ 0.9477 n.a. n.a. 1.4283780 293.43084 -23.05154 2024-Oct-31 13:20 01 34 28.79 +16 03 13.4 5.018128 39.126684 n.a. n.a. 1.002862943688 -0.4962090 0.01037865669920 -0.0601993 168.0258 /T 11.8511 175.5/ 0.9302 n.a. n.a. 1.4253989 291.86492 -18.60893 2024-Oct-31 13:30 01 34 27.87 +16 03 18.5 1.911157 39.250262 n.a. n.a. 1.002860953560 -0.4961874 0.01037844751619 -0.0441040 168.0158 /T 11.8610 175.5/ 0.9128 n.a. n.a. 1.4179473 290.37091 -13.92875 2024-Oct-31 13:40 t 01 34 26.94 +16 03 23.3 358.797148 39.261726 n.a. n.a. 1.002858963518 -0.4961658 0.01037830293630 -0.0279901 168.0058 /T 11.8709 175.5/ 0.8955 n.a. n.a. 1.4058933 288.93744 -9.021820 2024-Oct-31 13:50 01 34 26.02 +16 03 27.6 355.687829 39.161001 n.a. n.a. 1.002856973563 -0.4961443 0.01037822297211 -0.0118886 167.9958 /T 11.8808 175.5/ 0.8784 n.a. n.a. 1.3891354 287.55363 -3.907045 2024-Oct-31 14:00 01 34 25.11 +16 03 31.6 352.594802 38.948759 n.a. n.a. 1.002854983695 -0.4961227 0.01037820751185 0.0041696 167.9859 /T 11.8906 175.5/ 0.8614 n.a. n.a. 1.3675979 286.20886 1.3877377 2024-Oct-31 14:10 01 34 24.20 +16 03 35.3 349.529231 38.626408 n.a. n.a. 1.002852993913 -0.4961011 0.01037825631961 0.0201535 167.9760 /T 11.9004 175.5/ 0.8446 n.a. n.a. 1.3412300 284.89251 6.8257124 2024-Oct-31 14:20 01 34 23.31 +16 03 38.5 346.501571 38.196037 n.a. n.a. 1.002851004218 -0.4960795 0.01037836903593 0.0360324 167.9662 /T 11.9101 175.5/ 0.8280 n.a. n.a. 1.3100036 283.59364 12.362116 2024-Oct-31 14:30 01 34 22.43 +16 03 41.4 343.521320 37.660358 n.a. n.a. 1.002849014610 -0.4960579 0.01037854517833 0.0517758 167.9564 /T 11.9198 175.5/ 0.8116 n.a. n.a. 1.2739131 282.30061 17.946411 2024-Oct-31 14:40 01 34 21.58 +16 03 43.9 340.596848 37.022623 n.a. n.a. 1.002847025088 -0.4960362 0.01037878414243 0.0673534 167.9468 /T 11.9293 175.5/ 0.7954 n.a. n.a. 1.2329746 281.00063 23.525356 2024-Oct-31 14:50 01 34 20.76 +16 03 46.1 337.735269 36.286537 n.a. n.a. 1.002845035654 -0.4960146 0.01037908520305 0.0827353 167.9373 /T 11.9387 175.5/ 0.7793 n.a. n.a. 1.1872259 279.67908 29.046536 2024-Oct-31 15:00 01 34 19.96 +16 03 47.9 334.942390 35.456164 n.a. n.a. 1.002843046306 -0.4959930 0.01037944751570 0.0978918 167.9279 /T 11.9480 175.4/ 0.7635 n.a. n.a. 1.1367272 278.31868 34.461741 2024-Oct-31 15:10 01 34 19.20 +16 03 49.3 332.222702 34.535829 n.a. n.a. 1.002841057045 -0.4959713 0.01037987011821 0.1127940 167.9186 /T 11.9572 175.4/ 0.7479 n.a. n.a. 1.0815629 276.89823 39.729625 2024-Oct-31 15:20 01 34 18.47 +16 03 50.5 329.579430 33.530033 n.a. n.a. 1.002839067871 -0.4959496 0.01038035193271 0.1274131 167.9095 /T 11.9662 175.4/ 0.7325 n.a. n.a. 1.0218442 275.39085 44.817282 2024-Oct-31 15:30 01 34 17.79 +16 03 51.2 327.014614 32.443369 n.a. n.a. 1.002837078784 -0.4959280 0.01038089176765 0.1417212 167.9006 /T 11.9750 175.4/ 0.7173 n.a. n.a. 0.9577140 273.76117 49.700651 2024-Oct-31 15:40 01 34 17.15 +16 03 51.7 324.529217 31.280448 n.a. n.a. 1.002835089785 -0.4959063 0.01038148832024 0.1556908 167.8919 /T 11.9836 175.3/ 0.7023 n.a. n.a. 0.8893558 271.96103 54.363843 2024-Oct-31 15:50 01 34 16.55 +16 03 51.8 322.123252 30.045841 n.a. n.a. 1.002833100872 -0.4958846 0.01038214017897 0.1692952 167.8833 /T 11.9921 175.3/ 0.6876 n.a. n.a. 0.8170076 269.92243 58.797651 2024-Oct-31 16:00 01 34 16.01 +16 03 51.7 319.795916 28.744023 n.a. n.a. 1.002831112046 -0.4958629 0.01038284582642 0.1825083 167.8750 /T 12.0003 175.3/ 0.6732 n.a. n.a. 0.7409879 267.54543 62.997401 2024-Oct-31 16:10 01 34 15.53 +16 03 51.2 317.545714 27.379339 n.a. n.a. 1.002829123308 -0.4958412 0.01038360364225 0.1953048 167.8669 /T 12.0083 175.3/ 0.6589 n.a. n.a. 0.6617429 264.67684 66.960158 2024-Oct-31 16:20 01 34 15.10 +16 03 50.4 315.370593 25.955967 n.a. n.a. 1.002827134657 -0.4958195 0.01038441190637 0.2076603 167.8591 /T 12.0161 175.2/ 0.6450 n.a. n.a. 0.5799388 261.07011 70.680882 2024-Oct-31 16:30 01 34 14.73 +16 03 49.4 313.268050 24.477905 n.a. n.a. 1.002825146093 -0.4957977 0.01038526880236 0.2195512 167.8515 /T 12.0236 175.2/ 0.6312 n.a. n.a. 0.4966537 256.30694 74.146205 2024-Oct-31 16:40 01 34 14.43 +16 03 48.1 311.235240 22.948948 n.a. n.a. 1.002823157616 -0.4957760 0.01038617242104 0.2309548 167.8442 /T 12.0308 175.2/ 0.6178 n.a. n.a. 0.4138063 249.63874 77.322390 2024-Oct-31 16:50 01 34 14.20 +16 03 46.5 309.269061 21.372688 n.a. n.a. 1.002821169226 -0.4957542 0.01038712076411 0.2418495 167.8371 /T 12.0378 175.1/ 0.6045 n.a. n.a. 0.3351771 239.68067 80.128652 2024-Oct-31 17:00 01 34 14.03 +16 03 44.7 307.366236 19.752510 n.a. n.a. 1.002819180924 -0.4957325 0.01038811174824 0.2522144 167.8303 /T 12.0444 175.1/ 0.5916 n.a. n.a. 0.2687890 224.04797 82.377760 2024-Oct-31 17:10 01 34 13.94 +16 03 42.6 305.523369 18.091592 n.a. n.a. 1.002817192709 -0.4957107 0.01038914320898 0.2620299 167.8239 /T 12.0508 175.0/ 0.5789 n.a. n.a. 0.2305240 200.51441 83.695334 2024-Oct-31 17:20 01 34 13.92 +16 03 40.4 303.737003 16.392913 n.a. n.a. 1.002815204582 -0.4956889 0.01039021290513 0.2712774 167.8177 /T 12.0569 175.0/ 0.5665 n.a. n.a. 0.2390273 173.09456 83.685083 2024-Oct-31 17:30 01 34 13.98 +16 03 37.9 302.003655 14.659258 n.a. n.a. 1.002813216542 -0.4956671 0.01039131852298 0.2799394 167.8119 /T 12.0627 175.0/ 0.5543 n.a. n.a. 0.2936490 151.19686 82.493946 2024-Oct-31 17:40 01 34 14.12 +16 03 35.2 300.319852 12.893229 n.a. n.a. 1.002811228590 -0.4956453 0.01039245768095 0.2879995 167.8063 /T 12.0682 174.9/ 0.5424 n.a. n.a. 0.3772375 137.01116 80.655928 2024-Oct-31 17:50 01 34 14.34 +16 03 32.4 298.682150 11.097255 n.a. n.a. 1.002809240725 -0.4956235 0.01039362793413 0.2954426 167.8011 /T 12.0733 174.9/ 0.5308 n.a. n.a. 0.4765567 127.95991 78.543974 2024-Oct-31 18:00 01 34 14.64 +16 03 29.4 297.087152 9.273603 n.a. n.a. 1.002807252947 -0.4956017 0.01039482677912 0.3022546 167.7963 /T 12.0781 174.8/ 0.5194 n.a. n.a. 0.5849797 121.86922 76.332105 2024-Oct-31 18:10 A 01 34 15.03 +16 03 26.2 295.531516 7.424387 n.a. n.a. 1.002805265258 -0.4955798 0.01039605165877 0.3084228 167.7918 /T 12.0825 174.8/ 0.5083 n.a. n.a. 0.6992811 117.51809 74.096963 2024-Oct-31 18:20 A 01 34 15.50 +16 03 22.9 294.011961 5.551583 n.a. n.a. 1.002803277656 -0.4955580 0.01039729996730 0.3139356 167.7876 /T 12.0866 174.7/ 0.4975 n.a. n.a. 0.8177374 114.24505 71.873320 2024-Oct-31 18:30 A 01 34 16.06 +16 03 19.5 292.525267 3.657037 n.a. n.a. 1.002801290141 -0.4955361 0.01039856905514 0.3187827 167.7838 /T 12.0904 174.7/ 0.4869 n.a. n.a. 0.9393125 111.67717 69.677277 2024-Oct-31 18:40 A 01 34 16.71 +16 03 16.0 291.068273 1.742478 n.a. n.a. 1.002799302714 -0.4955143 0.01039985623424 0.3229554 167.7803 /T 12.0938 174.7/ 0.4766 n.a. n.a. 1.0633081 109.59269 67.516060 2024-Oct-31 18:50 N 01 34 17.45 +16 03 12.4 289.637866 -0.190471 n.a. n.a. 1.002797315375 -0.4954924 0.01040115878310 0.3264457 167.7772 /T 12.0968 174.6/ 0.4666 n.a. n.a. 1.1892035 107.85300 65.392438 >..... 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/horizons_batch.txt scripts https://ssd.jpl.nasa.gov/ftp/ssd/SCRIPTS Author : Jon.D.Giorgini@jpl.nasa.gov ***************************************************************************************************************************************************************************************************************************************************