API VERSION: 1.2 API SOURCE: NASA/JPL Horizons API ******************************************************************************* Revised: Jun 05, 2025 Chandra Spacecraft (X-ray observatory) / (Earth) -151 http://xrtpub.harvard.edu/index.html Chandra X-ray Observatory: Deployment (STS-93) = July 23, 1999 Data storage = 1.8 gbs Science mission = ~5 years Length (sun shade open) = 45.3 m Orbital check-out = 2 months Length (sun shade clsd) = 38.7 m ORBITAL DATA: Inclination = 28.5 degrees Orbital period = ~64 hours Apogee altitude = ~ 86,487 km Observing time / orbit = ~55 hours Perigee altitude = ~ 5,999 km WEIGHTS & PROPULSION: Dry = 10,560 lbs Propellant = 2,153 lbs Pressurant = 10 lb Total launch weight = 12,930 lb Engines = 4 Thrust per engine = 105 lb SPACECRAFT TRAJECTORY (from CFA): Trajectory after 2025-Jun-03 is a prediction Trajectory name Start Stop ---------------------------- ----------- ----------- cxo_99219_06045 1999-Aug-07 2006-Feb-14 cxo_06002_10103 2006-Feb-03 2010-Feb-25 CXO_10056_25338 2010-Feb-25 2025-Dec-04 ******************************************************************************* ******************************************************************************* Ephemeris / API_USER Sun Jun 22 10:43:59 2025 Pasadena, USA / Horizons ******************************************************************************* Target body name: Chandra Observatory (spacecraft) (-151) {source: chandra_merged} Center body name: Earth (399) {source: chandra_merged} Center-site name: iTelescope Obs.,Beryl Junc. (Sato) ******************************************************************************* Start time : A.D. 2024-Oct-31 00:00:00.0000 UT Stop time : A.D. 2024-Nov-01 00:00:00.0000 UT Step-size : 10 minutes ******************************************************************************* Target pole/equ : undefined Target radii : undefined Center geodetic : 246.3025, 37.7377919, 1.56349 {E-lon(deg),Lat(deg),Alt(km)} Center cylindric: 246.3025,5051.53114,3883.42609 {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: chandra_merged} Rel. light bend : Sun {source: chandra_merged} Rel. lght bnd GM: 1.3271E+11 km^3/s^2 Atmos refraction: NO (AIRLESS) RA format : HMS Time format : CAL Calendar mode : Mixed Julian/Gregorian RTS-only print : NO EOP file : eop.250620.p250916 EOP coverage : DATA-BASED 1962-JAN-20 TO 2025-JUN-20. PREDICTS-> 2025-SEP-15 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 >..... Daylight Cut-off Requested .....< 2024-Oct-31 00:50 Ce 20 01 56.37 +19 15 43.0 173.642459 71.501955 n.a. n.a. 0.992820072233 0.1046732 0.00054271156281 -1.7860050 90.1230 /T 89.8453 104.5/ 2.1701 n.a. n.a. 119.97143 148.90683 -66.21892 2024-Oct-31 01:00 Ct 20 02 40.45 +18 58 15.5 180.556404 71.304283 n.a. n.a. 0.992820492036 0.1046437 0.00053552407238 -1.7978889 90.2106 /T 89.7581 104.6/ 2.1503 n.a. n.a. 123.99895 149.20588 -65.94169 2024-Oct-31 01:10 N 20 03 25.58 +18 40 09.3 187.263493 70.877920 n.a. n.a. 0.992820911463 0.1044838 0.00052828786277 -1.8103034 90.3000 /T 89.6691 104.6/ 2.1303 n.a. n.a. 128.25912 149.46261 -65.65690 2024-Oct-31 01:20 N 20 04 11.86 +18 21 22.6 193.635491 70.236496 n.a. n.a. 0.992821329971 0.1041832 0.00052100071112 -1.8232958 90.3916 /T 89.5779 104.7/ 2.1101 n.a. n.a. 132.76540 149.67892 -65.36534 2024-Oct-31 01:30 N 20 04 59.42 +18 01 53.6 199.583889 69.399049 n.a. n.a. 0.992821746971 0.1037303 0.00051366020184 -1.8369149 90.4858 /T 89.4842 104.8/ 2.0898 n.a. n.a. 137.53285 149.85687 -65.06774 2024-Oct-31 01:40 A 20 05 48.38 +17 41 40.2 205.061716 68.387436 n.a. n.a. 0.992822161828 0.1031123 0.00050626372031 -1.8512113 90.5828 /T 89.3876 104.9/ 2.0692 n.a. n.a. 142.57831 149.99865 -64.76478 2024-Oct-31 01:50 A 20 06 38.87 +17 20 40.2 210.057406 67.224044 n.a. n.a. 0.992822573853 0.1023153 0.00049880844599 -1.8662370 90.6831 /T 89.2877 105.0/ 2.0484 n.a. n.a. 147.92064 150.10651 -64.45708 2024-Oct-31 02:00 A 20 07 31.02 +16 58 51.3 214.585057 65.930159 n.a. n.a. 0.992822982296 0.1013237 0.00049129134513 -1.8820463 90.7872 /T 89.1841 105.1/ 2.0275 n.a. n.a. 153.58096 150.18284 -64.14518 2024-Oct-31 02:10 20 08 24.98 +16 36 11.0 218.674652 64.525028 n.a. n.a. 0.992823386343 0.1001202 0.00048370916305 -1.8986951 90.8954 /T 89.0763 105.2/ 2.0064 n.a. n.a. 159.58297 150.23006 -63.82958 2024-Oct-31 02:20 20 09 20.90 +16 12 36.5 222.364163 63.025474 n.a. n.a. 0.992823785107 0.0986857 0.00047605841589 -1.9162417 91.0082 /T 88.9639 105.3/ 1.9851 n.a. n.a. 165.95327 150.25066 -63.51072 2024-Oct-31 02:30 20 10 18.95 +15 48 04.8 225.694010 61.445867 n.a. n.a. 0.992824177618 0.0969988 0.00046833538160 -1.9347467 91.1262 /T 88.8464 105.4/ 1.9637 n.a. n.a. 172.72181 150.24716 -63.18893 2024-Oct-31 02:40 20 11 19.29 +15 22 32.6 228.703604 59.798306 n.a. n.a. 0.992824562819 0.0950358 0.00046053609022 -1.9542732 91.2498 /T 88.7232 105.5/ 1.9422 n.a. n.a. 179.92232 150.22213 -62.86451 2024-Oct-31 02:50 20 12 22.11 +14 55 56.4 231.429455 58.092887 n.a. n.a. 0.992824939549 0.0927698 0.00045265631332 -1.9748869 91.3796 /T 88.5939 105.6/ 1.9205 n.a. n.a. 187.59291 150.17815 -62.53764 2024-Oct-31 03:00 20 13 27.62 +14 28 12.3 233.904302 56.337992 n.a. n.a. 0.992825306533 0.0901710 0.00044469155247 -1.9966568 91.5161 /T 88.4578 105.7/ 1.8987 n.a. n.a. 195.77670 150.11782 -62.20844 2024-Oct-31 03:10 20 14 36.01 +13 59 15.8 236.156881 54.540560 n.a. n.a. 0.992825662371 0.0872056 0.00043663702646 -2.0196550 91.6600 /T 88.3144 105.8/ 1.8768 n.a. n.a. 204.52266 150.04375 -61.87692 2024-Oct-31 03:20 20 15 47.52 +13 29 02.3 238.212042 52.706324 n.a. n.a. 0.992826005516 0.0838353 0.00042848765732 -2.0439573 91.8120 /T 88.1629 106.0/ 1.8549 n.a. n.a. 213.88654 149.95855 -61.54299 2024-Oct-31 03:30 20 17 02.38 +12 57 26.4 240.091037 50.840021 n.a. n.a. 0.992826334262 0.0800169 0.00042023805488 -2.0696437 91.9726 /T 88.0028 106.1/ 1.8328 n.a. n.a. 223.93201 149.86485 -61.20645 2024-Oct-31 03:40 20 18 20.88 +12 24 22.3 241.811876 48.945552 n.a. n.a. 0.992826646713 0.0757013 0.00041188249952 -2.0967985 92.1426 /T 87.8332 106.3/ 1.8107 n.a. n.a. 234.73208 149.76526 -60.86699 2024-Oct-31 03:50 20 19 43.28 +11 49 43.2 243.389685 47.026120 n.a. n.a. 0.992826940765 0.0708322 0.00040341492322 -2.1255112 92.3229 /T 87.6534 106.4/ 1.7885 n.a. n.a. 246.37078 149.66240 -60.52414 2024-Oct-31 04:00 20 21 09.92 +11 13 21.9 244.837040 45.084339 n.a. n.a. 0.992827214072 0.0653452 0.00039482888831 -2.1558768 92.5142 /T 87.4626 106.6/ 1.7663 n.a. n.a. 258.94520 149.55890 -60.17730 2024-Oct-31 04:10 20 22 41.13 +10 35 09.9 246.164257 43.122314 n.a. n.a. 0.992827464010 0.0591661 0.00038611756390 -2.1879964 92.7175 /T 87.2598 106.8/ 1.7440 n.a. n.a. 272.56811 149.45739 -59.82568 2024-Oct-31 04:20 20 24 17.29 +09 54 57.9 247.379631 41.141711 n.a. n.a. 0.992827687637 0.0522093 0.00037727369964 -2.2219781 92.9336 /T 87.0442 107.0/ 1.7217 n.a. n.a. 287.37105 149.36049 -59.46832 2024-Oct-31 04:30 20 25 58.84 +09 12 35.2 248.489628 39.143799 n.a. n.a. 0.992827881638 0.0443750 0.00036828959651 -2.2579376 93.1637 /T 86.8146 107.2/ 1.6995 n.a. n.a. 303.50835 149.27084 -59.10402 2024-Oct-31 04:40 20 27 46.24 +08 27 49.5 249.499032 37.129487 n.a. n.a. 0.992828042266 0.0355470 0.00035915707446 -2.2959993 93.4088 /T 86.5701 107.4/ 1.6772 n.a. n.a. 321.16204 149.19111 -58.73135 2024-Oct-31 04:50 20 29 40.03 +07 40 26.9 250.411031 35.099344 n.a. n.a. 0.992828165270 0.0255885 0.00034986743654 -2.3362967 93.6700 /T 86.3094 107.7/ 1.6549 n.a. n.a. 340.54821 149.12396 -58.34857 2024-Oct-31 05:00 20 31 40.81 +06 50 11.2 251.227272 33.053606 n.a. n.a. 0.992828245800 0.0143382 0.00034041142950 -2.3789736 93.9488 /T 86.0312 107.9/ 1.6327 n.a. n.a. 361.92506 149.07211 -57.95359 2024-Oct-31 05:10 20 33 49.27 +05 56 43.6 251.947848 30.992174 n.a. n.a. 0.992828278302 0.0016040 0.00033077920092 -2.4241852 94.2464 /T 85.7341 108.2/ 1.6106 n.a. n.a. 385.60331 149.03830 -57.54395 2024-Oct-31 05:20 20 36 06.18 +04 59 42.5 252.571242 28.914601 n.a. n.a. 0.992828256378 -0.0128438 0.00032096025287 -2.4720983 94.5643 /T 85.4168 108.5/ 1.5885 n.a. n.a. 411.95979 149.02531 -57.11667 2024-Oct-31 05:30 20 38 32.47 +03 58 42.0 253.094210 26.820058 n.a. n.a. 0.992828172616 -0.0292826 0.00031094339346 -2.5228921 94.9041 /T 85.0775 108.8/ 1.5664 n.a. n.a. 441.45538 149.03598 -56.66822 2024-Oct-31 05:40 20 41 09.18 +02 53 12.0 253.511576 24.707296 n.a. n.a. 0.992828018376 -0.0480496 0.00030071668728 -2.5767579 95.2675 /T 84.7147 109.2/ 1.5445 n.a. n.a. 474.65886 149.07323 -56.19435 2024-Oct-31 05:50 20 43 57.59 +01 42 36.3 253.815949 22.574582 n.a. n.a. 0.992827783521 -0.0695586 0.00029026740824 -2.6338985 95.6563 /T 84.3265 109.5/ 1.5226 n.a. n.a. 512.27921 149.14000 -55.68992 2024-Oct-31 06:00 20 46 59.16 +00 26 11.3 253.997312 20.419611 n.a. n.a. 0.992827456061 -0.0943227 0.00027958200000 -2.6945244 96.0724 /T 83.9110 109.9/ 1.5008 n.a. n.a. 555.20974 149.23936 -55.14873 2024-Oct-31 06:10 20 50 15.72 -00 56 55.5 254.042447 18.239393 n.a. n.a. 0.992827021701 -0.1229842 0.00026864605265 -2.7588492 96.5177 /T 83.4664 110.3/ 1.4792 n.a. n.a. 604.58944 149.37437 -54.56318 2024-Oct-31 06:20 20 53 49.44 -02 27 48.8 253.934142 16.030095 n.a. n.a. 0.992826463244 -0.1563577 0.00025744431219 -2.8270781 96.9939 /T 82.9908 110.7/ 1.4577 n.a. n.a. 661.88956 149.54815 -53.92391 2024-Oct-31 06:30 20 57 43.07 -04 07 49.0 253.650072 13.786832 n.a. n.a. 0.992825759782 -0.1954889 0.00024596074847 -2.8993886 97.5028 /T 82.4826 111.2/ 1.4363 n.a. n.a. 729.03786 149.76377 -53.21926 2024-Oct-31 06:40 21 02 00.03 -05 58 36.6 253.161234 11.503380 n.a. n.a. 0.992824885613 -0.2417407 0.00023417872796 -2.9758967 98.0453 /T 81.9407 111.7/ 1.4151 n.a. n.a. 808.60042 150.02410 -52.43452 2024-Oct-31 06:50 21 06 44.75 -08 02 20.1 252.429687 9.171786 n.a. n.a. 0.992823808735 -0.2969169 0.00022208137083 -3.0565964 98.6217 /T 81.3651 112.2/ 1.3940 n.a. n.a. 904.05291 150.33155 -51.55089 2024-Oct-31 07:00 21 12 03.04 -10 21 45.6 251.405266 6.781834 n.a. n.a. 0.992822488726 -0.3634490 0.00020965223288 -3.1412534 99.2300 /T 80.7575 112.6/ 1.3731 n.a. n.a. 1020.1942 150.68757 -50.54391 2024-Oct-31 07:10 21 18 02.78 -13 00 32.0 250.020670 4.320317 n.a. n.a. 0.992820873704 -0.4446794 0.00019687656594 -3.2292149 99.8650 /T 80.1232 113.1/ 1.3524 n.a. n.a. 1163.7910 151.09164 -49.38126 2024-Oct-31 07:20 21 24 54.99 -16 03 33.0 248.183962 1.770030 n.a. n.a. 0.992818895851 -0.5453037 0.00018374362550 -3.3190609 100.5150 /T 79.4739 113.5/ 1.3319 n.a. n.a. 1344.6059 151.53927 -48.01932 >..... Elevation Cut-off Requested .....< 2024-Oct-31 11:00 14 02 51.30 +32 27 16.4 47.377936 -0.059080 n.a. n.a. 0.992566571416 -2.1920598 0.00024180491099 3.2058395 46.9383 /L 133.0521 45.2/ 0.9438 n.a. n.a. 824.69396 58.476253 53.058683 2024-Oct-31 11:10 14 11 46.86 +33 33 44.5 46.782416 0.907530 n.a. n.a. 0.992557975291 -2.0962850 0.00025449379896 3.1224173 47.8729 /L 132.1168 46.7/ 0.9295 n.a. n.a. 743.40080 60.097300 53.778854 2024-Oct-31 11:20 14 20 04.91 +34 31 05.0 46.380067 1.849878 n.a. n.a. 0.992549743280 -2.0102108 0.00026685491984 3.0423796 48.7586 /L 131.2303 48.0/ 0.9155 n.a. n.a. 674.92501 61.586196 54.411286 2024-Oct-31 11:30 14 27 49.62 +35 20 56.1 46.138622 2.776989 n.a. n.a. 0.992541839576 -1.9323471 0.00027890186329 2.9657169 49.5975 /T 130.3908 49.2/ 0.9018 n.a. n.a. 616.57873 62.955718 54.971752 2024-Oct-31 11:40 14 35 04.51 +36 04 34.7 46.032349 3.696069 n.a. n.a. 0.992534233737 -1.8614955 0.00029064798623 2.8923317 50.3921 /T 129.5955 50.4/ 0.8884 n.a. n.a. 566.35021 64.217209 55.472778 2024-Oct-31 11:50 14 41 52.59 +36 43 01.5 46.040436 4.612922 n.a. n.a. 0.992526899660 -1.7966825 0.00030210615551 2.8220821 51.1454 /T 128.8415 51.4/ 0.8752 n.a. n.a. 522.70929 65.380764 55.924456 2024-Oct-31 12:00 14 48 16.43 +37 17 05.4 46.145835 5.532260 n.a. n.a. 0.992519814778 -1.7371088 0.00031328862360 2.7548066 51.8604 /T 128.1259 52.4/ 0.8624 n.a. n.a. 484.47504 66.455405 56.335027 2024-Oct-31 12:10 14 54 18.24 +37 47 25.6 46.334417 6.457931 n.a. n.a. 0.992512959447 -1.6821125 0.00032420698160 2.6903385 52.5398 /T 127.4459 53.3/ 0.8500 n.a. n.a. 450.72384 67.449221 56.711308 2024-Oct-31 12:20 14 59 59.96 +38 14 34.3 46.594355 7.393089 n.a. n.a. 0.992506316450 -1.6311408 0.00033487215663 2.6285142 53.1862 /T 126.7989 54.2/ 0.8378 n.a. n.a. 420.72464 68.369505 57.058997 2024-Oct-31 12:30 15 05 23.29 +38 38 58.1 46.915654 8.340324 n.a. n.a. 0.992499870604 -1.5837282 0.00034529443400 2.5691777 53.8020 /T 126.1824 55.0/ 0.8258 n.a. n.a. 393.89234 69.222855 57.382911 2024-Oct-31 12:40 A 15 10 29.70 +39 00 58.8 47.289798 9.301768 n.a. n.a. 0.992493608448 -1.5394801 0.00035548349256 2.5121826 54.3894 /T 125.5944 55.8/ 0.8142 n.a. n.a. 369.75399 70.015277 57.687159 2024-Oct-31 12:50 A 15 15 20.52 +39 20 54.8 47.709474 10.279168 n.a. n.a. 0.992487517983 -1.4980593 0.00036544844616 2.4573936 54.9503 /T 125.0329 56.6/ 0.8029 n.a. n.a. 347.92374 70.752260 57.975280 2024-Oct-31 13:00 A 15 19 56.89 +39 39 01.7 48.168363 11.273954 n.a. n.a. 0.992481588466 -1.4591764 0.00037519788696 2.4046858 55.4865 /T 124.4961 57.3/ 0.7919 n.a. n.a. 328.08413 71.438853 58.250342 2024-Oct-31 13:10 Nm 15 24 19.87 +39 55 32.3 48.660966 12.287288 n.a. n.a. 0.992475810230 -1.4225810 0.00038473992830 2.3539450 55.9996 /T 123.9824 57.9/ 0.7811 n.a. n.a. 309.97194 72.079720 58.515031 2024-Oct-31 13:20 Nm 15 28 30.38 +40 10 37.9 49.182476 13.320103 n.a. n.a. 0.992470174549 -1.3880557 0.00039408224561 2.3050669 56.4910 /T 123.4905 58.6/ 0.7707 n.a. n.a. 293.36736 72.679197 58.771710 2024-Oct-31 13:30 Nm 15 32 29.25 +40 24 27.9 49.728665 14.373139 n.a. n.a. 0.992464673508 -1.3554106 0.00040323211481 2.2579564 56.9620 /T 123.0189 59.2/ 0.7605 n.a. n.a. 278.08561 73.241338 59.022470 2024-Oct-31 13:40 Cm 15 36 17.23 +40 37 10.4 50.295798 15.446969 n.a. n.a. 0.992459299909 -1.3244790 0.00041219644770 2.2125269 57.4138 /T 122.5666 59.7/ 0.7506 n.a. n.a. 263.97044 73.769955 59.269172 2024-Oct-31 13:50 Cm 15 39 55.01 +40 48 52.4 50.880559 16.542024 n.a. n.a. 0.992454047179 -1.2951139 0.00042098182436 2.1686994 57.8473 /T 122.1325 60.3/ 0.7409 n.a. n.a. 250.88894 74.268653 59.513477 >..... 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 Author : Jon.D.Giorgini@jpl.nasa.gov ***************************************************************************************************************************************************************************************************************************************************