API VERSION: 1.2 API SOURCE: NASA/JPL Horizons API ******************************************************************************* Revised: Dec 04, 2024 Euclid Observatory (spacecraft) -680 https://www.esa.int/Science_Exploration/Space_Science/Euclid BACKGROUND: Euclid was built and operated by the European Space Agency with contributions from NASA. It launched July 01, 2023 @ 15:12 UTC on a SpaceX Falcon 9 from Cape Canaveral, Florida, USA. After a one-month transit, its operational orbit will halo around the Earth-Sun Lagrange point 2 (L2), at an average distance of 1.5 million km from Earth. This location keeps pace with Earth as it orbits the Sun (and also hosts ESA's Gaia and NASA's James Webb space telescopes, among others). Nominal mission lifetime is six years, with the possibility of extension (limited by the amount of cold gas used for propulsion). MISSION: Euclid is a cosmology survey mission, optimised to determine the properties of dark energy and dark matter on universal scales to address key questions: - What is the structure and history of the cosmic web? - What is the nature of dark matter? - How has the expansion of the Universe changed over time? - What is the nature of dark energy? - Is our understanding of gravity complete? In addition, Euclid will perform near-infrared spectroscopy of hundreds of millions of galaxies and stars. This will allow investigation of the chemical and kinematical properties of many targets in detail. Euclid's image quality will be at least four times sharper than that achieved by ground-based sky surveys. SPACECRAFT: 4.7m tall, 3.7 m diameter Two major components: service and payload modules Service module 850 kg Payload module 800 kg Propellant 210 kg Balancing mass 40 kg Service module contains: electric power generation and distribution attitude control data processing electronics propulsion telecommand and telemetry thermal control SCIENCE INSTRUMENTS (payload module): - 1.2-m diameter telescope - Visible-wavelength camera (the VISible instrument, VIS) - Near-Infrared Spectrometer and Photometer, NISP). SPACECRAFT TRAJECTORY From ESA 2024-Nov-25, predicts thereafter Trajectory name Start Stop -------------------------------------------- ----------- ----------- euclid_flp_00061_20230701_20310907_v01 2023-Jul-01 2031-Sep-07 ******************************************************************************* ******************************************************************************* Ephemeris / API_USER Thu Dec 12 02:03:54 2024 Pasadena, USA / Horizons ******************************************************************************* Target body name: Euclid (spacecraft) (-680) {source: Euclid_current} Center body name: Earth (399) {source: DE441} Center-site name: VdS Remote Observatory, Hakos ******************************************************************************* 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 : 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.241211.p250309 EOP coverage : DATA-BASED 1962-JAN-20 TO 2024-DEC-11. PREDICTS-> 2025-MAR-08 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-Nov-30 00:00 06 32 11.32 +27 23 01.7 14.356955 37.927289 n.a. n.a. 0.995385662848 -0.1810467 0.01042064435872 -0.0026081 150.4876 /L 29.2170 136.8/ 1.5713 n.a. n.a. 1.8885198 313.04023 -0.632250 2024-Nov-30 00:10 06 32 10.27 +27 23 14.2 11.596271 38.442176 n.a. n.a. 0.995384936832 -0.1809879 0.01042066647988 0.0136636 150.4983 /L 29.2064 136.9/ 1.5488 n.a. n.a. 1.8660567 310.90635 3.3226295 2024-Nov-30 00:20 06 32 09.20 +27 23 26.1 8.788327 38.847361 n.a. n.a. 0.995384211052 -0.1809291 0.01042075412695 0.0300633 150.5090 /L 29.1958 137.0/ 1.5266 n.a. n.a. 1.8408851 308.83526 7.3827804 2024-Nov-30 00:30 06 32 08.11 +27 23 37.2 5.943689 39.140205 n.a. n.a. 0.995383485508 -0.1808704 0.01042090775022 0.0465595 150.5198 /L 29.1850 137.2/ 1.5048 n.a. n.a. 1.8127455 306.82120 11.520406 2024-Nov-30 00:40 06 32 07.02 +27 23 47.7 3.073864 39.318747 n.a. n.a. 0.995382760200 -0.1808116 0.01042112767301 0.0631205 150.5307 /L 29.1742 137.3/ 1.4834 n.a. n.a. 1.7814081 304.85791 15.706222 2024-Nov-30 00:50 06 32 05.92 +27 23 57.5 0.191028 39.381771 n.a. n.a. 0.995382035128 -0.1807528 0.01042141409102 0.0797143 150.5416 /L 29.1634 137.4/ 1.4623 n.a. n.a. 1.7466718 302.93854 19.910606 2024-Nov-30 01:00 t 06 32 04.81 +27 24 06.6 357.307709 39.328846 n.a. n.a. 0.995381310291 -0.1806941 0.01042176707195 0.0963090 150.5526 /L 29.1526 137.5/ 1.4416 n.a. n.a. 1.7083641 301.05568 24.104796 2024-Nov-30 01:10 06 32 03.72 +27 24 15.1 354.436452 39.160339 n.a. n.a. 0.995380585690 -0.1806353 0.01042218655537 0.1128727 150.5635 /L 29.1418 137.6/ 1.4213 n.a. n.a. 1.6663406 299.20118 28.262007 2024-Nov-30 01:20 06 32 02.63 +27 24 22.8 351.589474 38.877405 n.a. n.a. 0.995379861325 -0.1805766 0.01042267235283 0.1293734 150.5744 /L 29.1309 137.7/ 1.4014 n.a. n.a. 1.6204844 297.36601 32.358338 2024-Nov-30 01:30 06 32 01.55 +27 24 29.9 348.778351 38.481947 n.a. n.a. 0.995379137195 -0.1805178 0.01042322414830 0.1457795 150.5853 /L 29.1202 137.8/ 1.3819 n.a. n.a. 1.5707062 295.54003 36.373408 2024-Nov-30 01:40 06 32 00.50 +27 24 36.3 346.013735 37.976557 n.a. n.a. 0.995378413301 -0.1804591 0.01042384149872 0.1620594 150.5961 /L 29.1094 138.0/ 1.3628 n.a. n.a. 1.5169439 293.71166 40.290673 2024-Nov-30 01:50 06 31 59.47 +27 24 42.0 343.305142 37.364429 n.a. n.a. 0.995377689643 -0.1804003 0.01042452383493 0.1781817 150.6068 /L 29.0988 138.1/ 1.3441 n.a. n.a. 1.4591636 291.86735 44.097442 2024-Nov-30 02:00 06 31 58.46 +27 24 47.1 340.660793 36.649273 n.a. n.a. 0.995376966220 -0.1803416 0.01042527046281 0.1941154 150.6174 /L 29.0882 138.2/ 1.3258 n.a. n.a. 1.3973602 289.99096 47.784644 2024-Nov-30 02:10 06 31 57.49 +27 24 51.5 338.087532 35.835211 n.a. n.a. 0.995376243033 -0.1802829 0.01042608056461 0.2098300 150.6279 /L 29.0778 138.3/ 1.3079 n.a. n.a. 1.3315594 288.06282 51.346404 2024-Nov-30 02:20 06 31 56.56 +27 24 55.3 335.590804 34.926673 n.a. n.a. 0.995375520081 -0.1802241 0.01042695320066 0.2252952 150.6383 /L 29.0675 138.4/ 1.2904 n.a. n.a. 1.2618211 286.05827 54.779487 2024-Nov-30 02:30 06 31 55.67 +27 24 58.4 333.174688 33.928303 n.a. n.a. 0.995374797365 -0.1801654 0.01042788731112 0.2404814 150.6486 /L 29.0573 138.5/ 1.2733 n.a. n.a. 1.1882449 283.94572 58.082670 2024-Nov-30 02:40 A 06 31 54.83 +27 25 00.9 330.841981 32.844862 n.a. n.a. 0.995374074885 -0.1801067 0.01042888171818 0.2553594 150.6586 /L 29.0473 138.6/ 1.2566 n.a. n.a. 1.1109783 281.68354 61.256055 2024-Nov-30 02:50 A 06 31 54.04 +27 25 02.9 328.594308 31.681150 n.a. n.a. 0.995373352640 -0.1800480 0.01042993512834 0.2699006 150.6685 /L 29.0375 138.7/ 1.2404 n.a. n.a. 1.0302311 279.21535 64.300327 2024-Nov-30 03:00 Am 06 31 53.30 +27 25 04.2 326.432256 30.441937 n.a. n.a. 0.995372630630 -0.1799893 0.01043104613499 0.2840772 150.6782 /L 29.0278 138.8/ 1.2245 n.a. n.a. 0.9462989 276.46245 67.215901 2024-Nov-30 03:10 Nm 06 31 52.63 +27 25 04.9 324.355520 29.131899 n.a. n.a. 0.995371908856 -0.1799306 0.01043221322115 0.2978620 150.6877 /L 29.0184 138.9/ 1.2090 n.a. n.a. 0.8596034 273.31159 70.001832 2024-Nov-30 03:20 Nm 06 31 52.02 +27 25 05.1 322.363044 27.755579 n.a. n.a. 0.995371187318 -0.1798719 0.01043343476252 0.3112288 150.6970 /L 29.0092 139.0/ 1.1940 n.a. n.a. 0.7707636 269.59417 72.654240 2024-Nov-30 03:30 Nm 06 31 51.47 +27 25 04.8 320.453163 26.317347 n.a. n.a. 0.995370466015 -0.1798132 0.01043470903064 0.3241518 150.7060 /L 29.0002 139.1/ 1.1793 n.a. n.a. 0.6807271 265.05049 75.163709 2024-Nov-30 03:40 Cm 06 31 51.00 +27 25 03.9 318.623733 24.821379 n.a. n.a. 0.995369744948 -0.1797545 0.01043603419632 0.3366065 150.7148 /L 28.9915 139.2/ 1.1650 n.a. n.a. 0.5910232 259.26790 77.510600 2024-Nov-30 03:50 Cm 06 31 50.60 +27 25 02.6 316.872245 23.271636 n.a. n.a. 0.995369024115 -0.1796958 0.01043740833320 0.3485691 150.7233 /L 28.9830 139.3/ 1.1511 n.a. n.a. 0.5042647 251.57947 79.656060 >..... Daylight Cut-off Requested .....< >..... Elevation Cut-off Requested .....< 2024-Nov-30 19:50 06 35 43.66 +27 37 25.5 59.024657 1.370264 n.a. n.a. 0.995300917462 -0.1740824 0.01048399068710 -0.2859617 150.5131 /L 29.1899 145.3/ 0.3546 n.a. n.a. 2.6331682 22.434223 -40.59400 2024-Nov-30 20:00 06 35 44.36 +27 37 49.8 57.981367 3.328987 n.a. n.a. 0.995300219377 -0.1740241 0.01048285275060 -0.2813929 150.5170 /L 29.1861 145.4/ 0.3450 n.a. n.a. 2.5649876 19.653783 -40.88416 2024-Nov-30 20:10 06 35 44.95 +27 38 13.9 56.894262 5.265272 n.a. n.a. 0.995299521525 -0.1739659 0.01048173452382 -0.2761343 150.5214 /L 29.1818 145.5/ 0.3355 n.a. n.a. 2.5009530 16.788377 -41.06936 2024-Nov-30 20:20 06 35 45.44 +27 38 37.7 55.761041 7.177439 n.a. n.a. 0.995298823907 -0.1739076 0.01048063875412 -0.2701957 150.5261 /L 29.1772 145.6/ 0.3261 n.a. n.a. 2.4412459 13.844579 -41.14124 2024-Nov-30 20:30 06 35 45.82 +27 39 01.3 54.579270 9.063673 n.a. n.a. 0.995298126523 -0.1738494 0.01047956814680 -0.2635882 150.5312 /L 29.1721 145.7/ 0.3169 n.a. n.a. 2.3859995 10.830647 -41.09126 2024-Nov-30 20:40 06 35 46.11 +27 39 24.6 53.346384 10.922016 n.a. n.a. 0.995297429373 -0.1737911 0.01047852535996 -0.2563243 150.5367 /L 29.1667 145.8/ 0.3078 n.a. n.a. 2.3352924 7.7564699 -40.91087 2024-Nov-30 20:50 06 35 46.29 +27 39 47.6 52.059695 12.750354 n.a. n.a. 0.995296732456 -0.1737329 0.01047751299939 -0.2484175 150.5425 /L 29.1609 146.0/ 0.2989 n.a. n.a. 2.2891438 4.6334196 -40.59153 2024-Nov-30 21:00 06 35 46.37 +27 40 10.3 50.716405 14.546407 n.a. n.a. 0.995296035772 -0.1736747 0.01047653361342 -0.2398829 150.5488 /L 29.1548 146.1/ 0.2901 n.a. n.a. 2.2475098 1.4741151 -40.12488 2024-Nov-30 21:10 06 35 46.37 +27 40 32.5 49.313622 16.307715 n.a. n.a. 0.995295339322 -0.1736165 0.01047558968812 -0.2307367 150.5553 /L 29.1483 146.2/ 0.2815 n.a. n.a. 2.2102817 358.29210 -39.50283 2024-Nov-30 21:20 06 35 46.27 +27 40 54.4 47.848382 18.031633 n.a. n.a. 0.995294643106 -0.1735582 0.01047468364229 -0.2209960 150.5623 /L 29.1415 146.3/ 0.2731 n.a. n.a. 2.1772857 355.10146 -38.71765 2024-Nov-30 21:30 06 35 46.08 +27 41 15.9 46.317682 19.715316 n.a. n.a. 0.995293947123 -0.1735000 0.01047381782293 -0.2106796 150.5695 /L 29.1343 146.4/ 0.2649 n.a. n.a. 2.1482857 351.91639 -37.76209 2024-Nov-30 21:40 06 35 45.80 +27 41 36.9 44.718515 21.355712 n.a. n.a. 0.995293251374 -0.1734418 0.01047299450056 -0.1998068 150.5771 /L 29.1268 146.6/ 0.2568 n.a. n.a. 2.1229874 348.75075 -36.62941 2024-Nov-30 21:50 06 35 45.45 +27 41 57.5 43.047919 22.949555 n.a. n.a. 0.995292555858 -0.1733836 0.01047221586479 -0.1883986 150.5850 /L 29.1190 146.7/ 0.2490 n.a. n.a. 2.1010445 345.61766 -35.31349 2024-Nov-30 22:00 06 35 45.01 +27 42 17.6 41.303038 24.493362 n.a. n.a. 0.995291860575 -0.1733254 0.01047148402013 -0.1764766 150.5932 /L 29.1109 146.8/ 0.2414 n.a. n.a. 2.0820664 342.52913 -33.80891 2024-Nov-30 22:10 06 35 44.50 +27 42 37.2 39.481195 25.983428 n.a. n.a. 0.995291165527 -0.1732672 0.01047080098176 -0.1640636 150.6017 /L 29.1025 146.9/ 0.2340 n.a. n.a. 2.0656271 339.49576 -32.11098 2024-Nov-30 22:20 06 35 43.92 +27 42 56.3 37.579974 27.415834 n.a. n.a. 0.995290470711 -0.1732090 0.01047016867167 -0.1511833 150.6105 /L 29.0938 147.0/ 0.2268 n.a. n.a. 2.0512744 336.52653 -30.21590 2024-Nov-30 22:30 06 35 43.26 +27 43 14.8 35.597321 28.786456 n.a. n.a. 0.995289776129 -0.1731508 0.01046958891484 -0.1378603 150.6195 /L 29.0849 147.2/ 0.2198 n.a. n.a. 2.0385390 333.62871 -28.12084 2024-Nov-30 22:40 06 35 42.54 +27 43 32.7 33.531660 30.090978 n.a. n.a. 0.995289081780 -0.1730926 0.01046906343573 -0.1241202 150.6288 /L 29.0757 147.3/ 0.2131 n.a. n.a. 2.0269437 330.80779 -25.82415 2024-Nov-30 22:50 06 35 41.77 +27 43 50.1 31.382015 31.324923 n.a. n.a. 0.995288387665 -0.1730345 0.01046859385479 -0.1099892 150.6383 /L 29.0663 147.4/ 0.2066 n.a. n.a. 2.0160113 328.06755 -23.32557 2024-Nov-30 23:00 06 35 40.93 +27 44 06.9 29.148146 32.483680 n.a. n.a. 0.995287693783 -0.1729763 0.01046818168537 -0.0954946 150.6480 /L 29.0567 147.5/ 0.2003 n.a. n.a. 2.0052719 325.41017 -20.62648 2024-Nov-30 23:10 06 35 40.05 +27 44 23.1 26.830688 33.562557 n.a. n.a. 0.995287000135 -0.1729181 0.01046782833067 -0.0806640 150.6580 /L 29.0468 147.7/ 0.1943 n.a. n.a. 1.9942692 322.83630 -17.73029 2024-Nov-30 23:20 06 35 39.11 +27 44 38.6 24.431288 34.556833 n.a. n.a. 0.995286306719 -0.1728599 0.01046753508107 -0.0655259 150.6681 /L 29.0368 147.8/ 0.1885 n.a. n.a. 1.9825650 320.34530 -14.64269 2024-Nov-30 23:30 06 35 38.14 +27 44 53.5 21.952735 35.461829 n.a. n.a. 0.995285613537 -0.1728018 0.01046730311145 -0.0501095 150.6784 /L 29.0266 147.9/ 0.1830 n.a. n.a. 1.9697433 317.93536 -11.37205 2024-Nov-30 23:40 06 35 37.12 +27 45 07.8 19.399066 36.272984 n.a. n.a. 0.995284920589 -0.1727436 0.01046713347903 -0.0344444 150.6888 /L 29.0162 148.0/ 0.1777 n.a. n.a. 1.9554135 315.60367 -7.929711 2024-Nov-30 23:50 06 35 36.07 +27 45 21.4 16.775642 36.985949 n.a. n.a. 0.995284227873 -0.1726855 0.01046702712118 -0.0185606 150.6994 /L 29.0057 148.2/ 0.1726 n.a. n.a. 1.9392120 313.34658 -4.330132 2024-Dec-01 00:00 06 35 34.99 +27 45 34.3 14.089177 37.596679 n.a. n.a. 0.995283535391 -0.1726273 0.01046698485359 -0.0024888 150.7102 /L 28.9951 148.3/ 0.1679 n.a. n.a. 1.9208037 311.15972 -0.590953 $$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 ***************************************************************************************************************************************************************************************************************************************************