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 Mon Sep 14 14:36:07 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: iTelescope Obs., Siding Spring ******************************************************************************* 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 : 149.0644, -31.2733577, 1.16499 {E-lon(deg),Lat(deg),Alt(km)} Center cylindric: 149.0644,5457.31536,-3292.4397 {E-lon(deg),Dxy(km),Dz(km)} Center pole/equ : ITRF93 {East-longitude positive} Center radii : 6378.137, 6378.137, 6356.752 km {Equator_a, b, pole_c} Target primary : Earth Vis. interferer : MOON (R_eq= 1737.400) km {source: 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.260911.p261208 EOP coverage : DATA-BASED 1962-JAN-20 TO 2026-SEP-11. PREDICTS-> 2026-DEC-07 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 .....< 2026-Sep-02 16:30 r 07 28 44.51 -06 13 35.1 97.494658 -0.233754 n.a. n.a. 1.008227201663 -1.7170372 0.00113112317345 1.0929600 51.0672 /L 128.8829 72.0/ 67.8678 n.a. n.a. 39.096250 81.717664 63.936543 2026-Sep-02 16:40 m 07 29 09.84 -06 12 37.7 96.237932 1.795660 n.a. n.a. 1.008220318526 -1.7119060 0.00113550830702 1.0847361 50.9673 /L 128.9827 72.0/ 67.8180 n.a. n.a. 37.564769 81.424749 64.576235 2026-Sep-02 16:50 m 07 29 34.14 -06 11 40.6 94.985539 3.833697 n.a. n.a. 1.008213455870 -1.7068149 0.00113986187042 1.0772507 50.8715 /L 129.0784 72.1/ 67.7689 n.a. n.a. 36.052946 81.102592 65.243511 2026-Sep-02 17:00 m 07 29 57.43 -06 10 43.7 93.734362 5.879321 n.a. n.a. 1.008206613533 -1.7017634 0.00114418683368 1.0705073 50.7797 /L 129.1700 72.1/ 67.7203 n.a. n.a. 34.562461 80.748459 65.936775 2026-Sep-02 17:10 m 07 30 19.71 -06 09 47.1 92.481230 7.931496 n.a. n.a. 1.008199791358 -1.6967507 0.00114848617762 1.0645079 50.6920 /L 129.2576 72.1/ 67.6722 n.a. n.a. 33.095028 80.359327 66.654136 2026-Sep-02 17:20 m 07 30 41.01 -06 08 50.6 91.222892 9.989181 n.a. n.a. 1.008192989192 -1.6917763 0.00115276288889 1.0592533 50.6083 /L 129.3412 72.2/ 67.6247 n.a. n.a. 31.652394 79.931849 67.393399 2026-Sep-02 17:30 m 07 31 01.33 -06 07 54.2 89.955988 12.051319 n.a. n.a. 1.008186206881 -1.6868396 0.00115701995477 1.0547431 50.5284 /L 129.4210 72.2/ 67.5775 n.a. n.a. 30.236337 79.462327 68.152071 2026-Sep-02 17:40 m 07 31 20.70 -06 06 57.9 88.677018 14.116823 n.a. n.a. 1.008179444276 -1.6819399 0.00116126035793 1.0509754 50.4523 /L 129.4969 72.2/ 67.5308 n.a. n.a. 28.848663 78.946676 68.927369 2026-Sep-02 17:50 m 07 31 39.13 -06 06 01.5 87.382305 16.184569 n.a. n.a. 1.008172701228 -1.6770768 0.00116548707108 1.0479472 50.3800 /L 129.5691 72.2/ 67.4844 n.a. n.a. 27.491204 78.380396 69.716231 2026-Sep-02 18:00 m 07 31 56.64 -06 05 05.1 86.067956 18.253384 n.a. n.a. 1.008165977594 -1.6722496 0.00116970305164 1.0456539 50.3113 /L 129.6376 72.2/ 67.4382 n.a. n.a. 26.165820 77.758538 70.515341 2026-Sep-02 18:10 m 07 32 13.25 -06 04 08.6 84.729823 20.322031 n.a. n.a. 1.008159273230 -1.6674577 0.00117391123626 1.0440896 50.2462 /L 129.7026 72.2/ 67.3924 n.a. n.a. 24.874391 77.075679 71.321152 2026-Sep-02 18:20 m 07 32 28.98 -06 03 12.0 83.363453 22.389193 n.a. n.a. 1.008152587995 -1.6627007 0.00117811453529 1.0432471 50.1846 /L 129.7640 72.2/ 67.3467 n.a. n.a. 23.618824 76.325907 72.129921 2026-Sep-02 18:30 m 07 32 43.86 -06 02 15.1 81.964030 24.453462 n.a. n.a. 1.008145921750 -1.6579781 0.00118231582738 1.0431179 50.1265 /L 129.8221 72.2/ 67.3012 n.a. n.a. 22.401041 75.502814 72.937748 2026-Sep-02 18:40 m 07 32 57.90 -06 01 18.0 80.526323 26.513312 n.a. n.a. 1.008139274359 -1.6532892 0.00118651795384 1.0436920 50.0716 /L 129.8768 72.2/ 67.2557 n.a. n.a. 21.222985 74.599510 73.740616 2026-Sep-02 18:50 m 07 33 11.13 -06 00 20.7 79.044609 28.567083 n.a. n.a. 1.008132645688 -1.6486336 0.00119072371320 1.0449579 50.0199 /L 129.9284 72.2/ 67.2103 n.a. n.a. 20.086610 73.608674 74.534438 2026-Sep-02 19:00 Am 07 33 23.58 -05 59 23.0 77.512600 30.612952 n.a. n.a. 1.008126035604 -1.6440108 0.00119493585576 1.0469030 49.9713 /L 129.9768 72.2/ 67.1649 n.a. n.a. 18.993880 72.522634 75.315108 2026-Sep-02 19:10 Am 07 33 35.27 -05 58 25.0 75.923353 32.648906 n.a. n.a. 1.008119443976 -1.6394203 0.00119915707796 1.0495132 49.9258 /L 130.0222 72.2/ 67.1194 n.a. n.a. 17.946759 71.333512 76.078548 2026-Sep-02 19:20 Am 07 33 46.22 -05 57 26.6 74.269173 34.672701 n.a. n.a. 1.008112870677 -1.6348617 0.00120339001718 1.0527732 49.8831 /L 130.0647 72.2/ 67.0738 n.a. n.a. 16.947200 70.033445 76.820764 2026-Sep-02 19:30 Nm 07 33 56.47 -05 56 27.8 72.541507 36.681829 n.a. n.a. 1.008106315578 -1.6303344 0.00120763724630 1.0566661 49.8432 /L 130.1045 72.2/ 67.0281 n.a. n.a. 15.997129 68.614897 77.537897 2026-Sep-02 19:40 Nm 07 34 06.04 -05 55 28.5 70.730815 38.673463 n.a. n.a. 1.008099778556 -1.6258381 0.00121190126849 1.0611739 49.8060 /L 130.1415 72.2/ 66.9821 n.a. n.a. 15.098422 67.071093 78.226278 2026-Sep-02 19:50 Nm 07 34 14.96 -05 54 28.8 68.826450 40.644400 n.a. n.a. 1.008093259487 -1.6213722 0.00121618451206 1.0662774 49.7713 /L 130.1760 72.1/ 66.9359 n.a. n.a. 14.252873 65.396591 78.882483 2026-Sep-02 20:00 Cm 07 34 23.27 -05 53 28.5 66.816511 42.590997 n.a. n.a. 1.008086758251 -1.6169364 0.00122048932542 1.0719561 49.7391 /L 130.2081 72.1/ 66.8893 n.a. n.a. 13.462152 63.588009 79.503390 2026-Sep-02 20:10 Cm 07 34 30.98 -05 52 27.7 64.687714 44.509086 n.a. n.a. 1.008080274727 -1.6125302 0.00122481797225 1.0781881 49.7091 /L 130.2379 72.1/ 66.8424 n.a. n.a. 12.727751 61.644884 80.086241 >..... Daylight Cut-off Requested .....< >..... Elevation Cut-off Requested .....< 2026-Sep-03 17:10 r 08 06 11.05 -03 47 44.6 94.584421 -0.090654 n.a. n.a. 1.007376860472 -1.2057222 0.00177768157313 0.4083683 42.2324 /L 137.6996 66.7/ 56.5969 n.a. n.a. 16.481150 79.484717 49.065378 2026-Sep-03 17:20 m 08 06 21.59 -03 47 13.6 93.300894 2.004944 n.a. n.a. 1.007372021452 -1.2032403 0.00177932199469 0.4048815 42.1933 /L 137.7387 66.6/ 56.5433 n.a. n.a. 15.659421 78.939515 50.242758 2026-Sep-03 17:30 m 08 06 31.57 -03 46 42.8 92.018949 4.105257 n.a. n.a. 1.007367192377 -1.2007660 0.00178094984603 0.4021273 42.1565 /L 137.7755 66.6/ 56.4906 n.a. n.a. 14.842182 78.327284 51.528858 2026-Sep-03 17:40 m 08 06 41.00 -03 46 11.9 90.735133 6.209217 n.a. n.a. 1.007362373218 -1.1982992 0.00178256806855 0.4001070 42.1219 /L 137.8101 66.6/ 56.4385 n.a. n.a. 14.031137 77.638167 52.922778 2026-Sep-03 17:50 m 08 06 49.88 -03 45 41.0 89.445935 8.315750 n.a. n.a. 1.007357563944 -1.1958397 0.00178417960666 0.3988209 42.0895 /L 137.8425 66.6/ 56.3870 n.a. n.a. 13.228058 76.860415 54.421597 2026-Sep-03 18:00 m 08 06 58.21 -03 45 10.1 88.147755 10.423763 n.a. n.a. 1.007352764527 -1.1933877 0.00178578740219 0.3982674 42.0593 /L 137.8726 66.5/ 56.3361 n.a. n.a. 12.434795 75.979953 56.020029 2026-Sep-03 18:10 m 08 07 06.00 -03 44 39.1 86.836870 12.532132 n.a. n.a. 1.007347974937 -1.1909429 0.00178739438902 0.3984441 42.0313 /L 137.9007 66.5/ 56.2858 n.a. n.a. 11.653295 74.979836 57.710115 2026-Sep-03 18:20 m 08 07 13.25 -03 44 08.1 85.509395 14.639693 n.a. n.a. 1.007343195146 -1.1885053 0.00178900348728 0.3993467 42.0054 /L 137.9265 66.5/ 56.2359 n.a. n.a. 10.885619 73.839557 59.480996 2026-Sep-03 18:30 m 08 07 19.97 -03 43 37.0 84.161244 16.745224 n.a. n.a. 1.007338425124 -1.1860749 0.00179061759792 0.4009697 41.9816 /L 137.9503 66.4/ 56.1865 n.a. n.a. 10.133978 72.534187 61.318779 2026-Sep-03 18:40 m 08 07 26.16 -03 43 05.7 82.788090 18.847434 n.a. n.a. 1.007333664843 -1.1836517 0.00179223959694 0.4033063 41.9599 /L 137.9719 66.4/ 56.1375 n.a. n.a. 9.4007702 71.033306 63.206543 2026-Sep-03 18:50 m 08 07 31.85 -03 42 34.4 81.385313 20.944944 n.a. n.a. 1.007328914275 -1.1812354 0.00179387232976 0.4063480 41.9403 /L 137.9916 66.4/ 56.0888 n.a. n.a. 8.6886341 69.299692 65.124493 2026-Sep-03 19:00 Am 08 07 37.02 -03 42 02.8 79.947951 23.036274 n.a. n.a. 1.007324173392 -1.1788262 0.00179551860567 0.4100853 41.9226 /L 138.0092 66.3/ 56.0403 n.a. n.a. 8.0005193 67.287786 67.050249 2026-Sep-03 19:10 Am 08 07 41.71 -03 41 31.1 78.470641 25.119814 n.a. n.a. 1.007319442167 -1.1764240 0.00179718119210 0.4145069 41.9070 /L 138.0248 66.3/ 55.9921 n.a. n.a. 7.3397784 64.941989 68.959251 2026-Sep-03 19:20 Am 08 07 45.91 -03 40 59.3 76.947553 27.193808 n.a. n.a. 1.007314720571 -1.1740286 0.00179886280913 0.4196004 41.8932 /L 138.0385 66.3/ 55.9441 n.a. n.a. 6.7102837 62.195041 70.825227 2026-Sep-03 19:30 Nm 08 07 49.64 -03 40 27.2 75.372321 29.256323 n.a. n.a. 1.007310008577 -1.1716400 0.00180056612386 0.4253518 41.8813 /L 138.0504 66.2/ 55.8961 n.a. n.a. 6.1165676 58.967032 72.620683 2026-Sep-03 19:40 Nm 08 07 52.92 -03 39 54.8 73.737965 31.305220 n.a. n.a. 1.007305306159 -1.1692582 0.00180229374505 0.4317460 41.8712 /L 138.0604 66.2/ 55.8482 n.a. n.a. 5.5639777 55.166245 74.317359 2026-Sep-03 19:50 Nm 08 07 55.75 -03 39 22.3 72.036804 33.338114 n.a. n.a. 1.007300613289 -1.1668831 0.00180404821761 0.4387663 41.8629 /L 138.0687 66.1/ 55.8003 n.a. n.a. 5.0588109 50.693961 75.886719 2026-Sep-03 20:00 Cm 08 07 58.15 -03 38 49.4 70.260363 35.352335 n.a. n.a. 1.007295929941 -1.1645147 0.00180583201742 0.4463949 41.8563 /L 138.0752 66.1/ 55.7524 n.a. n.a. 4.6083484 45.456722 77.300615 2026-Sep-03 20:10 Cm 08 08 00.14 -03 38 16.3 68.399279 37.344879 n.a. n.a. 1.007291256088 -1.1621530 0.00180764754604 0.4546126 41.8513 /L 138.0802 66.0/ 55.7043 n.a. n.a. 4.2206441 39.390150 78.532469 >..... Daylight Cut-off Requested .....< >..... Elevation Cut-off Requested .....< 2026-Sep-04 17:30 r 08 26 55.71 -02 17 07.6 92.883700 -0.179540 n.a. n.a. 1.006763908054 -0.9000644 0.00212985470400 0.0323099 37.6340 /L 142.2919 57.5/ 44.9688 n.a. n.a. 11.672257 77.220245 6.1331125 2026-Sep-04 17:40 m 08 27 03.09 -02 16 40.5 91.593069 1.931217 n.a. n.a. 1.006760295871 -0.8982457 0.00212998257885 0.0299903 37.6079 /L 142.3181 57.4/ 44.9126 n.a. n.a. 11.013995 76.436325 6.0334063 2026-Sep-04 17:50 m 08 27 10.03 -02 16 13.4 90.302008 4.044909 n.a. n.a. 1.006756690996 -0.8964295 0.00213010259567 0.0284083 37.5836 /L 142.3424 57.4/ 44.8572 n.a. n.a. 10.358950 75.547416 6.0759531 2026-Sep-04 18:00 m 08 27 16.51 -02 15 46.3 89.006978 6.160451 n.a. n.a. 1.006753093419 -0.8946158 0.00213021771440 0.0275645 37.5611 /L 142.3649 57.4/ 44.8026 n.a. n.a. 9.7088179 74.534988 6.2884122 2026-Sep-04 18:10 m 08 27 22.54 -02 15 19.2 87.704375 8.276746 n.a. n.a. 1.006749503131 -0.8928047 0.00213033089441 0.0274580 37.5404 /L 142.3857 57.3/ 44.7489 n.a. n.a. 9.0654212 73.376188 6.7049358 2026-Sep-04 18:20 m 08 27 28.13 -02 14 52.0 86.390498 10.392668 n.a. n.a. 1.006745920120 -0.8909960 0.00213044508888 0.0280866 37.5215 /L 142.4046 57.3/ 44.6959 n.a. n.a. 8.4307381 72.042618 7.3677468 2026-Sep-04 18:30 m 08 27 33.28 -02 14 24.7 85.061519 12.507053 n.a. n.a. 1.006742344378 -0.8891897 0.00213056323926 0.0294466 37.5044 /L 142.4217 57.2/ 44.6436 n.a. n.a. 7.8069511 70.498729 8.3289129 2026-Sep-04 18:40 m 08 27 37.98 -02 13 57.4 83.713439 14.618685 n.a. n.a. 1.006738775894 -0.8873859 0.00213068826953 0.0315330 37.4890 /L 142.4371 57.2/ 44.5919 n.a. n.a. 7.1965127 68.699726 9.6520647 2026-Sep-04 18:50 m 08 27 42.26 -02 13 30.1 82.342051 16.726283 n.a. n.a. 1.006735214658 -0.8855845 0.00213082308055 0.0343394 37.4754 /L 142.4508 57.1/ 44.5409 n.a. n.a. 6.6022361 66.588856 11.413412 2026-Sep-04 19:00 Am 08 27 46.10 -02 13 02.6 80.942896 18.828483 n.a. n.a. 1.006731660662 -0.8837856 0.00213097054439 0.0378578 37.4635 /L 142.4627 57.1/ 44.4904 n.a. n.a. 6.0274240 64.094024 13.700633 2026-Sep-04 19:10 Am 08 27 49.52 -02 12 35.0 79.511220 20.923822 n.a. n.a. 1.006728113895 -0.8819890 0.00213113349865 0.0420789 37.4533 /L 142.4729 57.1/ 44.4404 n.a. n.a. 5.4760449 61.123829 16.606835 2026-Sep-04 19:20 Am 08 27 52.53 -02 12 07.4 78.041914 23.010720 n.a. n.a. 1.006724574347 -0.8801947 0.00213131474081 0.0469920 37.4447 /L 142.4815 57.0/ 44.3908 n.a. n.a. 4.9529734 57.563607 20.214924 2026-Sep-04 19:30 Nm 08 27 55.13 -02 11 39.6 76.529468 25.087455 n.a. n.a. 1.006721042009 -0.8784028 0.00213151702267 0.0525851 37.4378 /L 142.4885 57.0/ 44.3416 n.a. n.a. 4.4642981 53.273211 24.566444 2026-Sep-04 19:40 Nm 08 27 57.34 -02 11 11.7 74.967899 27.152139 n.a. n.a. 1.006717516873 -0.8766133 0.00213174304468 0.0588446 37.4324 /L 142.4938 56.9/ 44.2928 n.a. n.a. 4.0176721 48.090624 29.612327 2026-Sep-04 19:50 Nm 08 27 59.16 -02 10 43.6 73.350694 29.202691 n.a. n.a. 1.006713998927 -0.8748260 0.00213199545059 0.0657558 37.4286 /L 142.4976 56.9/ 44.2442 n.a. n.a. 3.6226013 41.849668 35.157534 2026-Sep-04 20:00 Cm 08 28 00.60 -02 10 15.4 71.670732 31.236802 n.a. n.a. 1.006710488164 -0.8730411 0.00213227682190 0.0733024 37.4263 /L 142.4999 56.8/ 44.1958 n.a. n.a. 3.2903898 34.424489 40.837439 2026-Sep-04 20:10 Cm 08 28 01.67 -02 09 47.1 69.920208 33.251895 n.a. n.a. 1.006706984574 -0.8712584 0.00213258967260 0.0814669 37.4255 /L 142.5007 56.7/ 44.1476 n.a. n.a. 3.0332246 25.810552 46.175274 >..... Daylight 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 ***************************************************************************************************************************************************************************************************************************************************