API VERSION: 1.2 API SOURCE: NASA/JPL Horizons API ******************************************************************************* Revised: Jun 02, 2025 Deimos / (Mars) 402 SATELLITE PHYSICAL PROPERTIES: Radius (km) = 7.8 x 6.0 x 5.1 Density (g cm^-3) = 1.76 +- 0.30 Mass (10^20 kg ) = 1.80 (10^-5) Geometric Albedo = 0.06 (+- 0.15) V(1,0) = +12.89 SATELLITE ORBITAL DATA: Semi-major axis, a (km) = 23.4632(10^3) Orbital period = 1.263 d Eccentricity, e = 0.00033 Rotational period = Synchronous Inclination, i (deg) = 1.791 ******************************************************************************* ******************************************************************************* Ephemeris / API_USER Fri Sep 4 18:06:08 2026 Pasadena, USA / Horizons ******************************************************************************* Target body name: Deimos (402) {source: mar099} Center body name: Earth (399) {source: DE441} Center-site name: GEOCENTRIC ******************************************************************************* Start time : A.D. 2022-Jan-01 10:00:00.0000 UT Stop time : A.D. 2022-Jan-02 00:00:00.0000 UT Step-size : 60 minutes ******************************************************************************* Target pole/equ : IAU_DEIMOS {West-longitude positive} Target radii : 7.8, 6.0, 5.1 km {Equator_a, b, pole_c} Center geodetic : 0.0, 0.0, -6378.137 {E-lon(deg),Lat(deg),Alt(km)} Center cylindric: 0.0, 0.0, 0.0 {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 : Mars 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 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 (-90.0deg=NO ),Airmass (>38.000=NO), Daylight (NO ) Table cut-offs 2: Solar elongation ( 0.0,180.0=NO ),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 R.A.__(a-apparent)__DEC dRA*cosD d(DEC)/dt Azi____(a-app)___Elev dAZ*cosE d(ELV)/dt X_(sat-primary)_Y SatPANG L_Ap_Sid_Time a-mass mag_ex APmag S-brt Illu% Def_illu ang-sep/v Ang-diam ObsSub-LON ObsSub-LAT SunSub-LON SunSub-LAT SN.ang SN.dist NP.ang NP.dist hEcl-Lon hEcl-Lat r rdot delta deldot 1-way_down_LT VmagSn VmagOb S-O-T /r S-T-O T-O-M/MN_Illu% O-P-T PsAng PsAMV PlAng Cnst TDB-UT ObsEcLon ObsEcLat N.Pole-RA N.Pole-DC GlxLon GlxLat L_Ap_SOL_Time 399_ins_LT RA_3sigma DEC_3sigma SMAA_3sig SMIA_3sig Theta Area_3sig POS_3sigma RNG_3sigma RNGRT_3sig DOP_S_3sig DOP_X_3sig RT_delay_3sig Tru_Anom L_Ap_Hour_Ang phi PAB-LON PAB-LAT App_Lon_Sun RA_(ICRF-a-apparnt)_DEC I_dRA*cosD I_d(DEC)/dt Sky_motion Sky_mot_PA RelVel-ANG Lun_Sky_Brt sky_SNR UT1-UTC ******************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************** $$SOE 2022-Jan-01 10:00 16 46 37.55 -22 30 11.8 16 47 54.40 -22 32 29.2 103.2092 -13.2642 n.a. n.a. n.a. n.a. -0.426 -0.539 218.341 n.a. n.a. n.a. 15.667 5.194 97.75505 0.0002 0.6868/t 0.009197 180.320690 6.586070 196.164414 22.113049 96.81 0.00 31.5937 0.003 235.8671 -0.2056 1.535965664225 -1.8561869 2.33880785436247 -9.0988410 19.45127180 22.7218249 49.8685882 27.5588 /L 17.2292 8.541/ 2.8123 2.8520 276.929 277.664 -0.20918 Oph 69.183903 253.3952924 -0.1367405 313.61761 53.49527 357.659333 14.567663 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 17.2343 244.4799 -0.1717 155.4052312 16 46 36.23 -22 30 09.5 103.1802 -13.4875 1.7343003 97.323387 -10.51800 n.a. n.a. -0.11046 2022-Jan-01 11:00 16 46 45.00 -22 30 25.3 16 48 01.86 -22 32 42.4 103.2856 -13.2525 n.a. n.a. n.a. n.a. -2.836 0.964 288.776 n.a. n.a. n.a. 15.667 5.194 97.75283 0.0002 2.9951/* 0.009198 192.176393 6.692017 208.027396 22.097103 96.80 0.00 31.5831 0.003 235.8875 -0.2058 1.535924099286 -1.6017395 2.33859221087937 -8.8246248 19.44947834 22.8170714 49.8492548 27.5724 /L 17.2378 9.141/ 2.6470 12.5192 276.917 277.652 -0.20847 Oph 69.183904 253.4242104 -0.1368677 313.61763 53.49529 357.674582 14.542800 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 17.2429 244.5046 -0.1719 155.4280042 16 46 43.68 -22 30 22.9 103.2566 -13.4760 1.7355383 97.311636 -10.20173 n.a. n.a. -0.11046 2022-Jan-01 12:00 16 46 52.46 -22 30 38.8 16 48 09.32 -22 32 55.7 103.4629 -13.3047 n.a. n.a. n.a. n.a. -5.125 2.425 295.318 n.a. n.a. n.a. 15.666 5.193 97.75064 0.0002 5.6700/* 0.009198 204.032050 7.044088 219.890257 22.081070 96.78 0.00 31.5724 0.003 235.9080 -0.2060 1.535888357301 -1.3739920 2.33838304363403 -8.5625493 19.44773875 22.9622169 49.8838878 27.5859 /L 17.2462 9.742/ 2.4867 24.2156 276.905 277.700 -0.22569 Oph 69.183906 253.4531643 -0.1370022 313.61765 53.49531 357.689841 14.517902 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 17.2514 244.5293 -0.1720 155.3961156 16 46 51.14 -22 30 36.4 103.4338 -13.5286 1.7385803 97.327653 -9.888878 n.a. n.a. -0.11045 2022-Jan-01 13:00 16 46 59.93 -22 30 52.3 16 48 16.80 -22 33 09.1 103.7339 -13.4175 n.a. n.a. n.a. n.a. -7.197 3.781 297.713 n.a. n.a. n.a. 15.666 5.192 97.74847 0.0002 8.1302/* 0.009199 215.887631 7.620756 231.752954 22.064961 96.77 0.00 31.5617 0.003 235.9287 -0.2062 1.535857675715 -1.1826904 2.33817992300467 -8.3239095 19.44604945 23.1502263 49.9707903 27.5994 /L 17.2546 10.3/ 2.3314 36.0153 276.893 277.806 -0.25967 Oph 69.183907 253.4821829 -0.1371578 313.61767 53.49534 357.705111 14.492936 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 17.2598 244.5541 -0.1722 155.3126290 16 46 58.61 -22 30 50.0 103.7046 -13.6420 1.7433005 97.370016 -9.593904 n.a. n.a. -0.11045 2022-Jan-01 14:00 16 47 07.43 -22 31 06.1 16 48 24.30 -22 33 22.6 104.0873 -13.5852 n.a. n.a. n.a. n.a. -8.964 4.975 299.029 n.a. n.a. n.a. 15.666 5.191 97.74632 0.0002 10.2515/* 0.009200 227.743105 8.372448 243.615449 22.048788 96.76 0.00 31.5510 0.003 235.9495 -0.2065 1.535831075459 -1.0360181 2.33798215870933 -8.1189962 19.44440470 23.3721741 50.1058848 27.6128 /L 17.2629 10.9/ 2.1812 47.8413 276.881 277.962 -0.30844 Oph 69.183908 253.5112926 -0.1373476 313.61769 53.49536 357.720396 14.467873 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 17.2681 244.5791 -0.1724 155.1825643 16 47 06.11 -22 31 03.7 104.0577 -13.8106 1.7495024 97.436049 -9.330270 n.a. n.a. -0.11044 2022-Jan-01 15:00 16 47 14.95 -22 31 20.0 16 48 31.83 -22 33 36.2 104.5085 -13.7996 n.a. n.a. n.a. n.a. -10.348 5.955 299.918 n.a. n.a. n.a. 15.666 5.190 97.74420 0.0002 11.9394/* 0.009201 239.598451 9.197973 255.477713 22.032567 96.75 0.00 31.5403 0.003 235.9706 -0.2068 1.535807402932 -0.9402450 2.33778882939252 -7.9566545 19.44279682 23.6177974 50.2829369 27.6260 /L 17.2711 11.5/ 2.0360 59.6772 276.869 278.159 -0.36938 Oph 69.183909 253.5405160 -0.1375832 313.61770 53.49538 357.735698 14.442688 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 17.2763 244.6042 -0.1727 155.0126178 16 47 13.63 -22 31 17.7 104.4783 -14.0260 1.7569268 97.521994 -9.109750 n.a. n.a. -0.11043 2022-Jan-01 16:00 16 47 22.51 -22 31 34.1 16 48 39.40 -22 33 50.2 104.9796 -14.0506 n.a. n.a. n.a. n.a. -11.292 6.680 300.606 n.a. n.a. n.a. 15.666 5.188 97.74210 0.0002 13.1203/* 0.009201 251.453649 9.929912 267.339730 22.016314 96.73 0.00 31.5295 0.003 235.9919 -0.2073 1.535785379444 -0.8994603 2.33759882209889 -7.8439064 19.44121658 23.8760742 50.4938888 27.6391 /L 17.2792 12.1/ 1.8959 71.5172 276.857 278.387 -0.43944 Oph 69.183910 253.5698707 -0.1378742 313.61772 53.49540 357.751016 14.417361 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 17.2844 244.6295 -0.1731 154.8108624 16 47 21.19 -22 31 31.8 104.9490 -14.2780 1.7652625 97.623252 -8.941860 n.a. n.a. -0.11043 2022-Jan-01 17:00 16 47 30.10 -22 31 48.5 16 48 46.99 -22 34 04.4 105.4811 -14.3266 n.a. n.a. n.a. n.a. -11.756 7.119 301.197 n.a. n.a. n.a. 15.665 5.187 97.74002 0.0002 13.7431/* 0.009202 263.308687 10.364885 279.201489 22.000047 96.72 0.00 31.5186 0.003 236.0134 -0.2078 1.535763655978 -0.9153991 2.33741087991969 -7.7856516 19.43965351 24.1357801 50.7292754 27.6521 /L 17.2872 12.8/ 1.7610 83.3587 276.844 278.633 -0.51538 Oph 69.183912 253.5993688 -0.1382277 313.61774 53.49543 357.766352 14.391878 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 17.2924 244.6550 -0.1735 154.5864370 16 47 28.78 -22 31 46.2 105.4498 -14.5551 1.7741590 97.734646 -8.833465 n.a. n.a. -0.11042 2022-Jan-01 18:00 16 47 37.73 -22 32 03.2 16 48 54.63 -22 34 18.8 105.9917 -14.6146 n.a. n.a. n.a. n.a. -11.718 7.253 301.755 n.a. n.a. n.a. 15.665 5.187 97.73796 0.0002 13.7812/* 0.009203 275.163561 10.352860 291.062995 21.983784 96.71 0.00 31.5077 0.003 236.0352 -0.2084 1.535740870902 -0.9873715 2.33722365575033 -7.7844603 19.43809642 24.3859903 50.9786924 27.6650 /L 17.2952 13.4/ 1.6311 95.2000 276.831 278.886 -0.59386 Oph 69.183913 253.6290163 -0.1386484 313.61776 53.49545 357.781704 14.366231 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 17.3003 244.6806 -0.1740 154.3492319 16 47 36.41 -22 32 00.9 105.9597 -14.8443 1.7832413 97.850694 -8.788574 n.a. n.a. -0.11041 2022-Jan-01 19:00 16 47 45.40 -22 32 18.2 16 49 02.30 -22 34 33.6 106.4900 -14.9015 n.a. n.a. n.a. n.a. -11.181 7.077 302.329 n.a. n.a. n.a. 15.665 5.188 97.73592 0.0002 13.2328/* 0.009204 287.018271 9.887907 302.924261 21.967544 96.70 0.00 31.4967 0.003 236.0571 -0.2091 1.535715708155 -1.1122942 2.33703576984184 -7.8404662 19.43653382 24.6165066 51.2312837 27.6777 /L 17.3030 14.0/ 1.5065 107.0400 276.818 279.135 -0.67169 Oph 69.183914 253.6588132 -0.1391379 313.61778 53.49547 357.797071 14.340420 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 17.3082 244.7065 -0.1746 154.1095689 16 47 44.08 -22 32 15.9 106.4574 -15.1324 1.7921255 97.965881 -8.808304 n.a. n.a. -0.11041 2022-Jan-01 20:00 16 47 53.10 -22 32 33.5 16 49 10.01 -22 34 48.6 106.9551 -15.1741 n.a. n.a. n.a. n.a. -10.168 6.598 302.979 n.a. n.a. n.a. 15.665 5.190 97.73389 0.0002 12.1214/* 0.009204 298.872828 9.113170 314.785311 21.951342 96.68 0.00 31.4857 0.003 236.0793 -0.2100 1.535686953413 -1.2848258 2.33684586867702 -7.9513637 19.43495446 24.8182067 51.4762226 27.6902 /L 17.3109 14.6/ 1.3869 118.8772 276.805 279.369 -0.74587 Oph 69.183915 253.6887526 -0.1396950 313.61779 53.49550 357.812450 14.314451 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 17.3160 244.7325 -0.1753 153.8778776 16 47 51.78 -22 32 31.2 106.9219 -15.4060 1.8004355 98.074888 -8.890998 n.a. n.a. -0.11040 2022-Jan-01 21:00 16 48 00.84 -22 32 49.0 16 49 17.75 -22 35 03.9 107.3675 -15.4199 n.a. n.a. n.a. n.a. -8.721 5.838 303.796 n.a. n.a. n.a. 15.664 5.191 97.73187 0.0002 10.4948/* 0.009205 310.727246 8.233785 326.646178 21.935193 96.67 0.00 31.4746 0.003 236.1016 -0.2109 1.535653545845 -1.4975971 2.33665268265659 -8.1125093 19.43334778 24.9833171 51.7031635 27.7026 /L 17.3186 15.2/ 1.2726 130.7095 276.792 279.578 -0.81367 Oph 69.183917 253.7188221 -0.1403154 313.61781 53.49552 357.827838 14.288337 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 17.3238 244.7587 -0.1761 153.6643635 16 47 59.51 -22 32 46.7 107.3338 -15.6527 1.8078185 98.172800 -9.032452 n.a. n.a. -0.11039 2022-Jan-01 22:00 16 48 08.60 -22 33 04.8 16 49 25.51 -22 35 19.5 107.7099 -15.6273 n.a. n.a. n.a. n.a. -6.903 4.828 304.970 n.a. n.a. n.a. 15.664 5.192 97.72985 0.0002 8.4236/* 0.009206 322.581546 7.422187 338.506903 21.919110 96.66 0.00 31.4634 0.003 236.1240 -0.2119 1.535614623262 -1.7415275 2.33645508014365 -8.3171215 19.43170437 25.1056173 51.9026478 27.7150 /L 17.3264 15.8/ 1.1635 142.5327 276.778 279.755 -0.87270 Oph 69.183918 253.7490036 -0.1409923 313.61783 53.49554 357.843232 14.262096 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 17.3315 244.7850 -0.1770 153.4786684 16 48 07.27 -22 33 02.5 107.6757 -15.8609 1.8139609 98.255266 -9.226223 n.a. n.a. -0.11038 2022-Jan-01 23:00 16 48 16.38 -22 33 20.7 16 49 33.30 -22 35 35.2 107.9681 -15.7867 n.a. n.a. n.a. n.a. -4.789 3.612 307.025 n.a. n.a. n.a. 15.664 5.193 97.72782 0.0002 5.9989/* 0.009207 334.435754 6.781911 350.367534 21.903100 96.64 0.00 31.4523 0.003 236.1465 -0.2130 1.535569558764 -2.0062129 2.33625211557926 -8.5565719 19.43001637 25.1805866 52.0664537 27.7272 /L 17.3342 16.4/ 1.0595 154.3346 276.765 279.893 -0.92090 Oph 69.183919 253.7792742 -0.1417164 313.61785 53.49557 357.858627 14.235754 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 17.3393 244.8114 -0.1779 153.3295228 16 48 15.06 -22 33 18.4 107.9335 -16.0209 1.8186015 98.318628 -9.463989 n.a. n.a. -0.11037 2022-Jan-02 00:00 16 48 24.18 -22 33 36.8 16 49 41.11 -22 35 51.0 108.1313 -15.8903 n.a. n.a. n.a. n.a. -2.471 2.243 312.229 n.a. n.a. n.a. 15.664 5.193 97.72579 0.0002 3.3374/* 0.009208 346.289901 6.360780 2.228120 21.887170 96.63 0.00 31.4410 0.003 236.1690 -0.2141 1.535517987345 -2.2803694 2.33604306964230 -8.8207533 19.42827778 25.2055003 52.1878846 27.7393 /L 17.3420 17.0/ 0.9608 166.0623 276.751 279.987 -0.95660 Oph 69.183920 253.8096073 -0.1424765 313.61787 53.49559 357.874020 14.209339 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 17.3471 244.8378 -0.1788 153.2243943 16 48 22.86 -22 33 34.5 108.0965 -16.1250 1.8215432 98.360010 -9.735922 n.a. n.a. -0.11036 $$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. '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} 'R.A.__(a-apparent)__DEC' = Airless apparent right ascension and declination of the target center with respect to an instantaneous reference frame defined by the Earth equator of-date (z-axis) and meridian containing the Earth equinox of-date (x-axis, EOP-corrected IAU76/80). Compensated for down-leg light-time delay, gravitational deflection of light, stellar aberration, precession & nutation. Note: equinox (RA origin) is offset -53 mas from the of-date frame defined by the IAU06/00a P & N system. 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} 'dRA*cosD d(DEC)/dt' = The angular rate of change in apparent RA and DEC of the target. This is with respect to the non-inertial IAU76/80 Earth true equator and equinox of-date reference frame. d(RA)/dt is multiplied by the cosine of declination to provide a linear rate in the plane-of-sky. Units: ARCSECONDS PER HOUR '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 'dAZ*cosE d(ELV)/dt' = The rate of change of target center apparent azimuth and elevation (airless). d(AZ)/dt is multiplied by the cosine of the elevation angle. TOPOCENTRIC ONLY. Units: ARCSECOND PER MINUTE 'X_(sat-primary)_Y SatPANG' = Satellite apparent differential coordinates in the plane-of-sky with respect to the primary body along with the satellite position angle. Differential coordinates are defined in RA as: X= ((RA_sat - RA_primary) * cosine(DEC_primary)) ... and in DEC as: Y= (DEC_sat - DEC_primary) Non-lunar satellites only. "SatPANG" is the counter-clockwise (CCW) position angle from the reference-frame of-date north-pole to a line from the primary center to the satellite center. Units: ARCSECONDS (X & Y), DEGREES (pos, angle) 'L_Ap_Sid_Time' = Local Apparent Sidereal Time. The angle measured westward in the body true-equator of-date plane from the meridian containing the body-fixed observer to the meridian containing the true Earth equinox (defined by intersection of the true Earth equator of date with the ecliptic of date). TOPOCENTRIC ONLY. Units: HH MM SS.ffff (hours-minutes-seconds of time) 'a-mass mag_ex' = RELATIVE optical airmass and visual magnitude extinction. Airmass is the ratio between the absolute optical airmass for the targets' refracted CENTER point to the absolute optical airmass at zenith. Also output is the estimated visual magnitude extinction due to the atmosphere, as seen by the observer. AVAILABLE ONLY FOR TOPOCENTRIC EARTH SITES WHEN THE TARGET IS ABOVE THE HORIZON. Units: none (airmass) and magnitudes (extinction). '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 'Illu%' = Fraction of the target objects' assumed circular disk illuminated by Sun (phase), as seen by the observer. Units: PERCENT 'Def_illu' = Defect of illumination. The maximum angular width of the target body's assumed circular disk diameter NOT illuminated by the Sun. Units: ARCSECONDS 'ang-sep/v' = The angular separation between the center of the target object and the center of the (remote) primary body it revolves around, as seen by the observer, with target visibility code. Visibility codes (refers to limb-to-limb): /t = Transiting primary body disk /O = Occulted by primary body disk /p = Partial umbral eclipse /P = Occulted partial umbral eclipse /u = Total umbral eclipse /U = Occulted total umbral eclipse /- = Target is the primary body /* = None of above ("free and clear") The radius of both primary and target body is taken to be the equatorial value (maximum, given a triaxial shape). Atmospheric effects and oblateness aspect are NOT currently considered. Light-time is considered. Units: ARCSECONDS and visibility code 'Ang-diam' = The equatorial angular width of the target body full disk, if it were fully illuminated and visible to the observer. If the target body diameter is unknown "n.a." is output. Units: ARCSECONDS 'ObsSub-LON ObsSub-LAT' = Apparent planetodetic longitude and latitude of the center of the target disc seen by the OBSERVER at print-time. This is NOT exactly the same as the "nearest" sub-point for a non-spherical target shape (since the center of the disc might not be the point closest to the observer), but is generally very close if not a very irregular body shape. Down-leg light travel-time from target to observer is taken into account. Latitude is the angle between the equatorial plane and the line perpendicular to the reference ellipsoid of the body, so includes body oblateness. The reference ellipsoid is an oblate spheroid with a single flatness coefficient in which the y-axis body radius is taken to be the same value as the x-axis radius. Positive longitude is to the WEST for this target. Cartographic system is given in the header. Units: DEGREES DEGREES 'SunSub-LON SunSub-LAT' = Apparent sub-solar longitude and latitude of the Sun on the target. The apparent planetodetic longitude and latitude of the center of the target disc as seen from the Sun, as seen by the observer at print-time. This is NOT exactly the same as the "sub-solar" (nearest) point for a non-spherical target shape (since the center of the disc seen from the Sun might not be the closest point to the Sun), but is very close if not a highly irregular body shape. Light travel-time from Sun to target and from target to observer is taken into account. Latitude is the angle between the equatorial plane and the line perpendicular to the reference ellipsoid of the body. The reference ellipsoid is an oblate spheroid with a single flatness coefficient in which the y-axis body radius is taken to be the same value as the x-axis radius. Positive longitude is to the WEST for this target. Cartographic system is given in the header. Units: DEGREES DEGREES 'SN.ang SN.dist' = Targets' apparent sub-solar point position angle (counter-clockwise with respect to the direction of the true-of-date reference-frame north-pole) and its angular distance from the sub-observer point (center of disk) at print time. A negative distance indicates the sub-solar point is on the hidden hemisphere. Units: DEGREES and ARCSECONDS 'NP.ang NP.dist' = Targets' apparent north-pole position angle (counter-clockwise with respect to the direction of the true-of-date reference-frame north-pole) and its angular distance from the sub-observer point (center of disk) at observation time. A negative distance indicates the planets' north-pole is on the hidden hemisphere. Units: DEGREES and ARCSECONDS 'hEcl-Lon hEcl-Lat' = Geometric heliocentric J2000 ecliptic longitude and latitude of target center at the instant light leaves it to be observed at print time (print time minus down-leg light-time). Units: DEGREES '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 '1-way_down_LT' = 1-way down-leg light-time from target center to observer. The elapsed time since light (observed at print-time) would have left or reflected off a point at the center of the target. Units: MINUTES 'VmagSn VmagOb' = Magnitude of target centers' velocity with respect to the Sun ("VmagSn") and the observer ("VmagOb") at the time light left the target center to be observed (print time minus down-leg light-time). These are absolute values of the velocity vectors (total speeds) and do NOT indicate direction of motion. Units: 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 'O-P-T' = Observer-Primary-Target angle; apparent angle between a target satellite, its primarys' center and an observer at print time. Interior vertex angle at the primary. Units: DEGREES 'PsAng PsAMV' = The position angles of the extended Sun-to-target radius vector ("PsAng") and the negative of the targets' heliocentric velocity vector ("PsAMV"), as seen in the observers' plane-of-sky, measured counter-clockwise (east) from reference-frame north-pole. Primarily intended for ACTIVE COMETS, "PsAng" is an indicator of the comets' gas-tail orientation in the sky (being in the anti-sunward direction) while "PsAMV" is an indicator of dust-tail orientation. Units: DEGREES 'PlAng' = Angle between observer and target orbital plane, measured from center of target at the moment light seen at observation time leaves the target. Positive values indicate observer is above the objects' orbital plane, in the direction of reference-frame +z axis. Units: DEGREES 'Cnst' = Constellation ID; the 3-letter abbreviation for the name of the constellation containing the target centers' astrometric position, as defined by IAU (1930) boundary delineation. See documentation for list of abbreviations. 'TDB-UT' = Difference between the uniform Barycentric Dynamical time-scale and the Earth-rotation dependent Universal Time. Prior to 1962, the difference is with respect to UT1 (TDB-UT1) and the 0.002 second maximum amplitude distinction between TT and TDB is not maintained. For 1962 and later, the difference is with respect to UTC (TDB-UTC) and periodic terms less than 1.e-6 second are ignored. Values beyond the next July or January 1st may change if a leap-second is later required by the IERS. Values from the present date forward through the next ~78 days are predictions. Beyond that prediction interval, the last prediction is taken as a constant for all future dates. Units: SECONDS 'ObsEcLon ObsEcLat' = Observer-centered IAU76/80 ecliptic-of-date longitude and latitude of the target centers' apparent position, with light-time, gravitational deflection of light, and stellar aberrations. Units: DEGREES 'N.Pole-RA N.Pole-DC' = ICRF right ascension and declination of the target body's north-pole direction at the time light left the body to be observed at print time. Target pole/rotation model is given in the header. Units: DEGREES 'GlxLon GlxLat' = Observer-centered Galactic System II (post WW II) longitude and latitude of the target centers' apparent position, with light-time, gravitational deflection of light, and stellar aberrations. Units: DEGREES 'L_Ap_SOL_Time' = Local Apparent SOLAR Time for observing site. This is the time indicated by a sundial. TOPOCENTRIC ONLY. Units: HH MM SS.ffff (sexagesimal angular hours) '399_ins_LT' = Instantaneous light-time of the station with respect to Earth center at print-time. The geometric (or "true") separation of site and Earth center, divided by the speed of light. Units: MINUTES 'RA_3sigma DEC_3sigma' = Uncertainty in Right-Ascension and Declination. Output values are the formal +/- 3 standard-deviations (sigmas) around nominal position. Units: ARCSECONDS 'SMAA_3sig SMIA_3sig Theta Area_3sig' = Plane-of-sky (POS) error ellipse data. These quantities summarize the targets' 3-dimensional 3-standard-deviation formal uncertainty volume projected into a reference plane perpendicular to the observers' line-of-sight. SMAA_3sig = Angular width of the 3-sigma error ellipse semi-major axis in POS. Units: ARCSECONDS. SMIA_3sig = Angular width of the 3-sigma error ellipse semi-minor axis in POS. Units: ARCSECONDS. Theta = Orientation angle of the error ellipse in POS; the clockwise angle from the direction of increasing RA to the semi-major axis of the error ellipse, in the direction of increasing DEC. Units: DEGREES. +DEC ^ \ | theta\| +RA <----+----- |\ | \ Area_3sig = Area of sky enclosed by the 3-sigma error ellipse. Units: ARCSECONDS ^ 2. 'POS_3sigma' = The Root-Sum-of-Squares (RSS) of the 3-standard deviation plane-of-sky error ellipse major and minor semi-axes. This single pointing uncertainty number gives an angular distance (a circular radius) from the targets' nominal position in the sky that encompasses the error-ellipse. Units: ARCSECONDS. 'RNG_3sigma RNGRT_3sig' = Range and range rate (radial velocity) formal 3-standard-deviation uncertainties. Units: KM, KM/S 'DOP_S_3sig DOP_X_3sig RT_delay_3sig' = Doppler radar uncertainties at S-band (2380 MHz) and X-band (8560 MHz) frequencies, along with the round-trip (total) delay to first-order. Units: HERTZ and SECONDS 'Tru_Anom' = Apparent true anomaly angle of the targets' heliocentric orbit position; the angle in the targets' instantaneous orbit plane from the orbital periapse direction to the target, measured positively in the direction of motion. The position of the target is taken to be at the moment light seen by the observer at print-time would have left the center of the object. That is, the heliocentric position of the target used to compute the true anomaly is one down-leg light-time prior to the print-time. Units: DEGREES 'L_Ap_Hour_Ang' = Local apparent HOUR ANGLE of target at observing site. The angle between the observers' meridian plane, containing Earth's axis of-date and local zenith direction, and a great circle passing through Earth's axis-of-date and the targets' direction, measured westward from the zenith meridian to target meridian along the equator. Negative values are angular times UNTIL transit. Positive values are angular times SINCE transit. Exactly 24_hrs/360_degrees. EARTH TOPOCENTRIC ONLY. Units: sHH MM SS.fff (sexagesimal angular hours) 'phi PAB-LON PAB-LAT' = "phi" is the true PHASE ANGLE at the observers' location at print time. "PAB-LON" and "PAB-LAT" are the J2000 ecliptic longitude and latitude of the phase angle bisector direction; the outward directed angle bisecting the arc created by the apparent vector from Sun to target center and the astrometric vector from observer to target center. For an otherwise uniform ellipsoid, the time when its long-axis is perpendicular to the PAB direction approximately corresponds to lightcurve maximum (or maximum brightness) of the body. PAB is discussed in Harris et al., Icarus 57, 251-258 (1984). Units: DEGREES, DEGREES, DEGREES 'App_Lon_Sun' = The apparent target-centered longitude of the Sun ("apparent L_s") as seen at the target when the light recorded by the observer at print-time reflected off the target. It is referred to a coordinate system where the x-axis is the equinox direction defined by the targets' instantaneous IAU2015 pole direction and heliocentric orbit plane at reflection time, and is measured positively in an eastward direction (counter-clockwise around the positive pole of the solar system angular momentum vector). On bodies other than the Earth, the quantity can indicate boundary dates for the seasons: Northern hemisphere Southern hemisphere 0= Spring Equinox 0= Autumn Equinox 90= Summer Solstice 90= Winter Solstice 180= Autumn Equinox 180= Spring Equinox 270= Winter Solstice 270= Summer Solstice For Earth seasons, instead see quantity #31 ("ObsEcLon") as seen from the geocenter, with the Sun as a target. If the target has no associated spin-pole model (common for asteroids and comets), "n.a." will be output. Units: DEGREES 'RA_(ICRF-a-apparnt)_DEC' = Airless apparent right ascension and declination coordinates of the target in the ICRF reference frame, with down-leg light-time, gravitational deflection of light, and stellar aberration. Units: RA : HH MM SS.ff{ffff} (hours-minutes-seconds of time) DEC: DG MN SC.f{ffff} (degrees-minutes-seconds of arc) 'I_dRA*cosD I_d(DEC)/dt' = The angular rate of change in the targets' ICRF inertial reference-frame apparent RA and DEC, with light-time, gravitational light deflection, and stellar aberrations. d(RA)/dt is multiplied by the cosine of declination to provide a linear rate in the plane-of-sky. Units: ARCSECONDS PER HOUR '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 'Lun_Sky_Brt sky_SNR' = Sky brightness due to moonlight scattered by Earth's atmosphere at the target's position in the sky. "sky_SNR" is the visual signal-to-noise ratio (SNR) of the target's surface brightness relative to background sky. Output only for topocentric Earth observers when both the Moon and target are above the local horizon and the Sun is in astronomical twilight (or further) below the horizon, and the target is not the Moon or Sun. If all conditions are not met, "n.a." is output. Galactic brightness, local sky light-pollution and weather are NOT considered. Lunar opposition surge is considered. The value returned is accurate under ideal conditions at the approximately 8-23% level, so is a useful but not definitive value. If the target-body radius is also known, "sky_SNR" is output. This is the approximate visual signal-to-noise ratio of the target's brightness divided by lunar sky brightness. When sky_SNR < 1, the target is dimmer than the ideal moonlight-scattering background sky, so unlikely to be detectable at visual wavelengths. In practice, visibility requires sky_SNR > 1 and a detector sensitive enough to reach the target's magnitude, even if it isn't washed out by moonlight. When relating magnitudes and brightness values, keep in mind their logarithmic relationship m2-m1 = -2.5*log_10(b2/b1). UNITS: VISUAL MAGNITUDES / ARCSECOND^2, and unitless ratio 'UT1-UTC' = Difference between the UT1 and UTC timescales ("DUT1"). UT1 is the Earth-rotation dependent mean solar time on the Greenwich meridian sometimes referred to as GMT. UTC is a discontinuous timescale derived from the atomic TAI timescale, adjusted by leap seconds to provide a civil timescale maintained within 0.9 seconds of UT1. Therefore, the difference UT1-UTC will have discontinuities where leap-seconds are inserted in UTC. UTC is not well-defined prior to 1962, so "n.a." will be returned for earlier dates. The UT1 here is a JPL fit to measurements of the Earth rotation which can change rapidly and unpredictably at the 10^-4 second level due to tides and other factors affecting Earth rotation. Values for the 14 days prior to the present date are considered provisional and may change at up to the 0.002 second level as data accumulates, corresponding to about 1-meter (3-sigma) for an Earth equatorial site. Values from the present date forward through the next ~78 days are predictions. Beyond that prediction interval, the last prediction is taken as a constant for all future dates. Units: SECONDS 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 ********************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************