API VERSION: 1.2 API SOURCE: NASA/JPL Horizons API ******************************************************************************* Revised: Aug 26, 2026 Spektr-R Telescope (Spacecraft) -557 (Earth orbiting) http://www.spaceflightnow.com/news/n1107/18spektr/ BACKGROUND: Russian Earth-orbiting radio telescope funded by Russian Astro Space Center. It was launched from the Baikonur Cosmodrome on July 18, 2011 at 02:31 UTC by a Zenit-3M launcher with Fregat-SB upper stage. MISSION OBJECTIVES: The primary scientific goal of Spektr-R over the planned 5-year mission is the study of astronomical objects at an angular resolution of a few millionths of an arcsecond. This is accomplished by using the satellite interferometrically in conjunction with ground-based observatories, including Arecibo and Greenbank. The primary targets are extragalactic. Characteristics of near-Earth and interplanetary plasma will also be studied. Wavelengths used are 1.35-6.0, 18.0 and 92.0 cm. PHYSICAL DATA: Mass : 3295 kg Diameter: 10 m SPACECRAFT TRAJECTORY: Perigee: ~ 10,000 km Apogee : ~390,000 km TRAJECTORY: The IKI (Russian Space Research Institute) provided an official trajectory for Nov 1-16 (2011). TLEs are used for other times, and are low-precision, especially during the following intervals which are extrapolations over data gaps: 2011: 2012: 2013: Jul 22 - Aug 04 Feb 26 - Apr 24 Jan 16 - Jun 02 Aug 12 - Oct 04 May 11 - May 29 Jul 04 - Jul 14 Dec 09 - Feb 17 (2012) Jun 12 - Aug 30 Oct 16 - Nov 02 Sep 08 - Jan 08 (2013) Dec 24 - Jan 10 Jan 19 - Feb 22 May 09 - May 27 Trajectory name Start Stop ------------------------------ ----------------- ----------------- TLEs 2011-Jun-18 06:09 2011-Nov-01 11:01 spectr_111101_111116_111102 2011-Nov-01 11:01 2011-Nov-16 01:07 TLEs 2011-Nov-16 01:07 Current ******************************************************************************* ******************************************************************************* Ephemeris / API_USER Sat Sep 5 00:49:03 2026 Pasadena, USA / Horizons ******************************************************************************* Target body name: Spektr-R Observatory (spacecraft) (-557) {source: spektr-r_MERGED} Center body name: Earth (399) {source: DE441} Center-site name: Deep Random Survey, El Sauce ******************************************************************************* Start time : A.D. 2026-Sep-02 00:00:00.0000 UT Stop time : A.D. 2026-Sep-05 00:00:00.0000 UT Step-size : 10 minutes ******************************************************************************* Target pole/equ : undefined Target radii : undefined Center geodetic : 289.1467, -30.5262851, 1.74234 {E-lon(deg),Lat(deg),Alt(km)} Center cylindric: 289.1467,5500.35467,-3221.64998 {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.260904.p261201 EOP coverage : DATA-BASED 1962-JAN-20 TO 2026-SEP-04. PREDICTS-> 2026-NOV-30 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 .....< 2026-Sep-02 06:30 m 06 51 25.88 -08 16 10.3 99.731193 -0.143545 n.a. n.a. 1.008685871242 -2.1361236 0.00070945969790 1.7627231 60.2097 /L 119.7555 69.3/ 72.1116 n.a. n.a. 94.195866 83.326549 65.378828 2026-Sep-02 06:40 m 06 52 27.49 -08 14 18.5 98.566427 1.754438 n.a. n.a. 1.008677316827 -2.1264634 0.00071651557829 1.7441451 59.9614 /L 120.0036 69.4/ 72.0627 n.a. n.a. 90.484421 83.116799 65.803726 2026-Sep-02 06:50 m 06 53 26.62 -08 12 27.9 97.405029 3.667343 n.a. n.a. 1.008668800912 -2.1169353 0.00072349866007 1.7264895 59.7230 /L 120.2417 69.6/ 72.0144 n.a. n.a. 86.892697 82.892814 66.242619 2026-Sep-02 07:00 m 06 54 23.36 -08 10 38.3 96.244669 5.594105 n.a. n.a. 1.008660322970 -2.1075365 0.00073041264245 1.7097543 59.4942 /L 120.4702 69.7/ 71.9667 n.a. n.a. 83.416774 82.653417 66.695068 2026-Sep-02 07:10 m 06 55 17.77 -08 08 49.5 95.082930 7.533665 n.a. n.a. 1.008651882488 -2.0982641 0.00073726121513 1.6939368 59.2748 /L 120.6894 69.9/ 71.9196 n.a. n.a. 80.053192 82.397371 67.160502 2026-Sep-02 07:20 m 06 56 09.95 -08 07 01.5 93.917297 9.484967 n.a. n.a. 1.008643478962 -2.0891153 0.00074404805551 1.6790336 59.0644 /L 120.8995 70.0/ 71.8730 n.a. n.a. 76.798912 82.123385 67.638219 2026-Sep-02 07:30 m 06 56 59.95 -08 05 14.3 92.745135 11.446948 n.a. n.a. 1.008635111900 -2.0800875 0.00075077682558 1.6650405 58.8627 /L 121.1010 70.2/ 71.8270 n.a. n.a. 73.651268 81.830108 68.127381 2026-Sep-02 07:40 m 06 57 47.84 -08 03 27.6 91.563668 13.418534 n.a. n.a. 1.008626780821 -2.0711779 0.00075745116866 1.6519525 58.6695 /L 121.2940 70.3/ 71.7813 n.a. n.a. 70.607938 81.516131 68.627018 2026-Sep-02 07:50 m 06 58 33.71 -08 01 41.5 90.369955 15.398628 n.a. n.a. 1.008618485253 -2.0623839 0.00076407470590 1.6397635 58.4844 /L 121.4788 70.4/ 71.7361 n.a. n.a. 67.666904 81.179993 69.136026 2026-Sep-02 08:00 m 06 59 17.60 -07 59 55.9 89.160858 17.386107 n.a. n.a. 1.008610224739 -2.0537030 0.00077065103246 1.6284666 58.3072 /L 121.6557 70.5/ 71.6913 n.a. n.a. 64.826423 80.820183 69.653175 2026-Sep-02 08:10 m 06 59 59.59 -07 58 10.6 87.933017 19.379809 n.a. n.a. 1.008601998826 -2.0451326 0.00077718371360 1.6180540 58.1376 /L 121.8251 70.6/ 71.6468 n.a. n.a. 62.084995 80.435150 70.177108 2026-Sep-02 08:20 m 07 00 39.74 -07 56 25.6 86.682803 21.378521 n.a. n.a. 1.008593807076 -2.0366703 0.00078367628058 1.6085167 57.9754 /L 121.9871 70.7/ 71.6025 n.a. n.a. 59.441339 80.023313 70.706354 2026-Sep-02 08:30 m 07 01 18.12 -07 54 40.9 85.406281 23.380970 n.a. n.a. 1.008585649059 -2.0283138 0.00079013222644 1.5998445 57.8203 /L 122.1420 70.8/ 71.5585 n.a. n.a. 56.894361 79.583076 71.239334 2026-Sep-02 08:40 m 07 01 54.79 -07 52 56.2 84.099159 25.385809 n.a. n.a. 1.008577524354 -2.0200606 0.00079655500155 1.5920264 57.6719 /L 122.2900 70.9/ 71.5147 n.a. n.a. 54.443134 79.112850 71.774374 2026-Sep-02 08:50 m 07 02 29.81 -07 51 11.7 82.756730 27.391596 n.a. n.a. 1.008569432549 -2.0119085 0.00080294800922 1.5850500 57.5302 /L 122.4315 70.9/ 71.4710 n.a. n.a. 52.086873 78.611076 72.309718 2026-Sep-02 09:00 m 07 03 03.24 -07 49 27.1 81.373805 29.396784 n.a. n.a. 1.008561373243 -2.0038553 0.00080931460102 1.5789019 57.3948 /L 122.5667 71.0/ 71.4274 n.a. n.a. 49.824906 78.076258 72.843541 2026-Sep-02 09:10 m 07 03 35.15 -07 47 42.5 79.944641 31.399690 n.a. n.a. 1.008553346043 -1.9958988 0.00081565807222 1.5735676 57.2655 /L 122.6958 71.1/ 71.3838 n.a. n.a. 47.656661 77.507004 73.373972 2026-Sep-02 09:20 m 07 04 05.59 -07 45 57.8 78.462845 33.398475 n.a. n.a. 1.008545350563 -1.9880369 0.00082198165703 1.5690311 57.1420 /L 122.8190 71.1/ 71.3402 n.a. n.a. 45.581635 76.902072 73.899101 2026-Sep-02 09:30 m 07 04 34.62 -07 44 12.9 76.921279 35.391113 n.a. n.a. 1.008537386428 -1.9802676 0.00082828852404 1.5652757 57.0240 /L 122.9367 71.2/ 71.2965 n.a. n.a. 43.599373 76.260430 74.417011 2026-Sep-02 09:40 Am 07 05 02.31 -07 42 27.7 75.311942 37.375352 n.a. n.a. 1.008529453269 -1.9725889 0.00083458177132 1.5622831 56.9115 /L 123.0490 71.2/ 71.2527 n.a. n.a. 41.709451 75.581318 74.925787 2026-Sep-02 09:50 Am 07 05 28.71 -07 40 42.3 73.625833 39.348673 n.a. n.a. 1.008521550725 -1.9649987 0.00084086442187 1.5600340 56.8040 /L 123.1562 71.3/ 71.2087 n.a. n.a. 39.911446 74.864330 75.423546 2026-Sep-02 10:00 Am 07 05 53.88 -07 38 56.5 71.852804 41.308239 n.a. n.a. 1.008513678445 -1.9574954 0.00084713941893 1.5585081 56.7014 /L 123.2585 71.3/ 71.1646 n.a. n.a. 38.204916 74.109494 75.908450 2026-Sep-02 10:10 Nm 07 06 17.88 -07 37 10.4 69.981389 43.250831 n.a. n.a. 1.008505836083 -1.9500769 0.00085340962140 1.5576837 56.6035 /L 123.3562 71.3/ 71.1202 n.a. n.a. 36.589379 73.317367 76.378731 2026-Sep-02 10:20 Nm 07 06 40.77 -07 35 23.9 67.998621 45.172774 n.a. n.a. 1.008498023302 -1.9427415 0.00085967779935 1.5575382 56.5099 /L 123.4495 71.3/ 71.0754 n.a. n.a. 35.064282 72.489133 76.832713 2026-Sep-02 10:30 Nm 07 07 02.61 -07 33 36.9 65.889833 47.069850 n.a. n.a. 1.008490239771 -1.9354875 0.00086594662958 1.5580478 56.4206 /L 123.5387 71.4/ 71.0303 n.a. n.a. 33.628988 71.626704 77.268825 2026-Sep-02 10:40 Cm 07 07 23.45 -07 31 49.5 63.638466 48.937193 n.a. n.a. 1.008482485165 -1.9283132 0.00087221869138 1.5591877 56.3351 /L 123.6238 71.4/ 70.9848 n.a. n.a. 32.282743 70.732813 77.685626 2026-Sep-02 10:50 Cm 07 07 43.34 -07 30 01.6 61.225885 50.769159 n.a. n.a. 1.008474759170 -1.9212169 0.00087849646244 1.5609321 56.2534 /L 123.7053 71.4/ 70.9389 n.a. n.a. 31.024659 69.811101 78.081814 >..... Daylight Cut-off Requested .....< >..... Elevation Cut-off Requested .....< 2026-Sep-03 07:40 r 07 55 17.02 -04 33 46.0 95.278680 0.167727 n.a. n.a. 1.007670237245 -1.3620955 0.00157293252947 0.6050743 44.7482 /L 135.1889 69.5/ 61.0412 n.a. n.a. 20.686727 80.251725 56.973358 2026-Sep-03 07:50 m 07 55 30.30 -04 33 10.2 94.028519 2.267426 n.a. n.a. 1.007664772158 -1.3590518 0.00157536330579 0.6007314 44.6979 /L 135.2392 69.5/ 60.9894 n.a. n.a. 19.721859 79.791957 57.986690 2026-Sep-03 08:00 m 07 55 42.93 -04 32 34.4 92.780607 4.372727 n.a. n.a. 1.007659319247 -1.3560207 0.00157777808263 0.5971245 44.6501 /L 135.2868 69.5/ 60.9383 n.a. n.a. 18.763681 79.278388 59.064612 2026-Sep-03 08:10 m 07 55 54.91 -04 31 58.7 91.531578 6.482607 n.a. n.a. 1.007653878463 -1.3530021 0.00158017981607 0.5942554 44.6050 /L 135.3319 69.5/ 60.8878 n.a. n.a. 17.813978 78.703959 60.204165 2026-Sep-03 08:20 m 07 56 06.24 -04 31 22.9 90.278006 8.596041 n.a. n.a. 1.007648449754 -1.3499960 0.00158257146672 0.5921247 44.5624 /L 135.3745 69.5/ 60.8379 n.a. n.a. 16.874585 78.060428 61.401317 2026-Sep-03 08:30 m 07 56 16.94 -04 30 47.2 89.016376 10.711985 n.a. n.a. 1.007643033073 -1.3470023 0.00158495599439 0.5907313 44.5224 /L 135.4144 69.5/ 60.7886 n.a. n.a. 15.947393 77.338139 62.650895 2026-Sep-03 08:40 m 07 56 27.01 -04 30 11.5 87.743047 12.829372 n.a. n.a. 1.007637628370 -1.3440207 0.00158733635241 0.5900731 44.4849 /L 135.4519 69.5/ 60.7397 n.a. n.a. 15.034359 76.525740 63.946553 2026-Sep-03 08:50 m 07 56 36.45 -04 29 35.6 86.454218 14.947097 n.a. n.a. 1.007632235596 -1.3410512 0.00158971548213 0.5901463 44.4499 /L 135.4868 69.4/ 60.6912 n.a. n.a. 14.137520 75.609845 65.280767 2026-Sep-03 09:00 m 07 56 45.28 -04 28 59.7 85.145884 17.064001 n.a. n.a. 1.007626854703 -1.3380936 0.00159209630731 0.5909459 44.4174 /L 135.5193 69.4/ 60.6431 n.a. n.a. 13.259003 74.574626 66.644869 2026-Sep-03 09:10 m 07 56 53.50 -04 28 23.6 83.813795 19.178865 n.a. n.a. 1.007621485645 -1.3351479 0.00159448172844 0.5924652 44.3872 /L 135.5494 69.4/ 60.5953 n.a. n.a. 12.401048 73.401327 68.029127 2026-Sep-03 09:20 m 07 57 01.13 -04 27 47.4 82.453403 21.290387 n.a. n.a. 1.007616128374 -1.3322139 0.00159687461709 0.5946965 44.3594 /L 135.5772 69.4/ 60.5478 n.a. n.a. 11.566035 72.067698 69.422854 2026-Sep-03 09:30 m 07 57 08.17 -04 27 11.0 81.059814 23.397167 n.a. n.a. 1.007610782843 -1.3292916 0.00159927781020 0.5976303 44.3339 /L 135.6026 69.3/ 60.5006 n.a. n.a. 10.756513 70.547346 70.814550 2026-Sep-03 09:40 Am 07 57 14.65 -04 26 34.4 79.627717 25.497691 n.a. n.a. 1.007605449007 -1.3263807 0.00160169410452 0.6012560 44.3107 /L 135.6257 69.3/ 60.4534 n.a. n.a. 9.9752419 68.809050 72.192064 2026-Sep-03 09:50 Am 07 57 20.57 -04 25 57.6 78.151326 27.590301 n.a. n.a. 1.007600126819 -1.3234812 0.00160412625084 0.6055614 44.2897 /L 135.6467 69.3/ 60.4064 n.a. n.a. 9.2252423 66.816076 73.542765 2026-Sep-03 10:00 Am 07 57 25.95 -04 25 20.5 76.624294 29.673175 n.a. n.a. 1.007594816235 -1.3205930 0.00160657694854 0.6105330 44.2708 /L 135.6655 69.2/ 60.3595 n.a. n.a. 8.5098524 64.525670 74.853703 2026-Sep-03 10:10 Nm 07 57 30.81 -04 24 43.2 75.039631 31.744294 n.a. n.a. 1.007589517210 -1.3177160 0.00160904883998 0.6161559 44.2540 /L 135.6822 69.2/ 60.3125 n.a. n.a. 7.8327909 61.888980 76.111770 2026-Sep-03 10:20 Nm 07 57 35.16 -04 24 05.5 73.389606 33.801404 n.a. n.a. 1.007584229699 -1.3148500 0.00161154450503 0.6224138 44.2392 /L 135.6969 69.2/ 60.2654 n.a. n.a. 7.1982162 58.851886 77.303838 2026-Sep-03 10:30 Nm 07 57 39.01 -04 23 27.5 71.665642 35.841975 n.a. n.a. 1.007578953658 -1.3119950 0.00161406645575 0.6292891 44.2263 /L 135.7097 69.1/ 60.2183 n.a. n.a. 6.6107647 55.357508 78.416925 2026-Sep-03 10:40 Cm 07 57 42.40 -04 22 49.2 69.858196 37.863156 n.a. n.a. 1.007573689045 -1.3091508 0.00161661713103 0.6367630 44.2153 /L 135.7206 69.1/ 60.1710 n.a. n.a. 6.0755345 51.351467 79.438409 2026-Sep-03 10:50 Cm 07 57 45.33 -04 22 10.5 67.956639 39.861708 n.a. n.a. 1.007568435815 -1.3063174 0.00161919889153 0.6448154 44.2061 /L 135.7297 69.0/ 60.1234 n.a. n.a. 5.5979588 46.791160 80.356396 >..... Daylight Cut-off Requested .....< >..... Elevation Cut-off Requested .....< 2026-Sep-04 08:10 m 08 19 48.14 -02 50 10.8 92.600309 1.335749 n.a. n.a. 1.006978202308 -1.0065746 0.00201907040459 0.1582812 39.1898 /L 140.7376 61.2/ 49.4598 n.a. n.a. 12.422494 77.669032 27.564378 2026-Sep-04 08:20 m 08 19 56.01 -02 49 43.3 91.340045 3.461715 n.a. n.a. 1.006974162227 -1.0045808 0.00201970608108 0.1561609 39.1617 /L 140.7657 61.2/ 49.4052 n.a. n.a. 11.715925 76.908044 28.629876 2026-Sep-04 08:30 m 08 20 03.40 -02 49 15.7 90.077754 5.590513 n.a. n.a. 1.006970130153 -1.0025907 0.00202033469854 0.1547833 39.1355 /L 140.7919 61.2/ 49.3514 n.a. n.a. 11.014001 76.044286 29.915546 2026-Sep-04 08:40 m 08 20 10.31 -02 48 48.1 88.809904 7.721096 n.a. n.a. 1.006966106071 -1.0006044 0.00202095923552 0.1541481 39.1113 /L 140.8162 61.1/ 49.2983 n.a. n.a. 10.318492 75.059746 31.444349 2026-Sep-04 08:50 m 08 20 16.73 -02 48 20.4 87.532879 9.852396 n.a. n.a. 1.006962089967 -0.9986218 0.00202158266719 0.1542538 39.0889 /L 140.8385 61.1/ 49.2459 n.a. n.a. 9.6312927 73.932252 33.238702 2026-Sep-04 09:00 m 08 20 22.69 -02 47 52.7 86.242941 11.983317 n.a. n.a. 1.006958081825 -0.9966430 0.00202220795974 0.1550975 39.0685 /L 140.8590 61.1/ 49.1942 n.a. n.a. 8.9544508 72.634314 35.318535 2026-Sep-04 09:10 m 08 20 28.17 -02 47 25.0 84.936199 14.112717 n.a. n.a. 1.006954081631 -0.9946678 0.00202283806467 0.1566749 39.0499 /L 140.8775 61.0/ 49.1431 n.a. n.a. 8.2902158 71.131612 37.698406 2026-Sep-04 09:20 m 08 20 33.19 -02 46 57.1 83.608563 16.239398 n.a. n.a. 1.006950089370 -0.9926963 0.00202347591302 0.1589800 39.0333 /L 140.8942 61.0/ 49.0926 n.a. n.a. 7.6411012 69.381013 40.383588 2026-Sep-04 09:30 m 08 20 37.75 -02 46 29.2 82.255703 18.362091 n.a. n.a. 1.006946105028 -0.9907283 0.00202412440975 0.1620057 39.0184 /L 140.9091 60.9/ 49.0426 n.a. n.a. 7.0099741 67.328039 43.365215 2026-Sep-04 09:40 Am 08 20 41.85 -02 46 01.2 80.872999 20.479439 n.a. n.a. 1.006942128590 -0.9887640 0.00202478642802 0.1657434 39.0053 /L 140.9221 60.9/ 48.9930 n.a. n.a. 6.4001788 64.903698 46.614969 2026-Sep-04 09:50 Am 08 20 45.52 -02 45 33.0 79.455493 22.589980 n.a. n.a. 1.006938160041 -0.9868033 0.00202546480340 0.1701829 38.9941 /L 140.9334 60.9/ 48.9438 n.a. n.a. 5.8157070 62.020799 50.080302 2026-Sep-04 10:00 Am 08 20 48.74 -02 45 04.7 77.997825 24.692123 n.a. n.a. 1.006934199369 -0.9848461 0.00202616232830 0.1753128 38.9845 /L 140.9429 60.8/ 48.8950 n.a. n.a. 5.2614265 58.570247 53.681648 2026-Sep-04 10:10 Nm 08 20 51.54 -02 44 36.3 76.494173 26.784130 n.a. n.a. 1.006930246558 -0.9828925 0.00202688174624 0.1811202 38.9767 /L 140.9507 60.8/ 48.8464 n.a. n.a. 4.7433750 54.418878 57.313143 2026-Sep-04 10:20 Nm 08 20 53.92 -02 44 07.6 74.938177 28.864083 n.a. n.a. 1.006926301594 -0.9809423 0.00202762574638 0.1875909 38.9705 /L 140.9569 60.7/ 48.7981 n.a. n.a. 4.2690927 49.412442 60.847816 2026-Sep-04 10:30 Nm 08 20 55.90 -02 43 38.9 73.322865 30.929857 n.a. n.a. 1.006922364464 -0.9789956 0.00202839695793 0.1947091 38.9660 /L 140.9614 60.7/ 48.7499 n.a. n.a. 3.8479001 43.391014 64.147218 2026-Sep-04 10:40 Cm 08 20 57.48 -02 43 09.9 71.640567 32.979079 n.a. n.a. 1.006918435154 -0.9770524 0.00202919794472 0.2024581 38.9630 /L 140.9644 60.6/ 48.7018 n.a. n.a. 3.4908659 36.228220 67.074803 >..... Daylight Cut-off Requested .....< >..... 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 Inquiries : Jon.D.Giorgini@jpl.nasa.gov ***************************************************************************************************************************************************************************************************************************************************