API VERSION: 1.2 API SOURCE: NASA/JPL Horizons API ******************************************************************************* Revised: Nov 04, 2024 James Webb Space Telescope / (E-S L2) -170 https://www.jwst.nasa.gov/index.html https://www.youtube.com/watch?v=bTxLAGchWnA The James Webb Space Telescope ("JWST" or "Webb") is a space-based infrared observatory and NASA's successor to the Hubble Space Telescope. Launched by Ariane 5 booster on 2021-Dec-25 @ 12:20 UTC from the ELA-3 launch complex near Korou, French Guiana. After launch, the telescope will deploy during its 30-day, 1.5 million km journey to halo orbit at the second Earth-Sun Lagrange point (E-S L2). Mission duration is nominally 5-10 years. GOALS - Search for the first galaxies or luminous objects formed after the Big Bang - Determine how galaxies evolved from their formation until now - Observe the formation of stars from the first stages to the formation of planetary systems - Measure the physical and chemical properties of planetary systems, including our own Solar System, investigating the potential for life in those systems. TELESCOPE * total launch mass : ~6200 kg (observatory, fuel, launch adaptor) * primary mirror : 25 m^2 mass : 705 kg material : beryllium coated w/48.25 grams gold (golf-ball size) segment mass : 20.1 kg, 39.48 kg for entire segment assembly No. of segments : 18 * focal length : 131.4 meters * optical resolution: 0.1 arcseconds * wavelength : 0.6 - 28.5 microns * size of sun shield: 21.197 m x 14.162 m * Sun shield layers : 1: Max temp 283K, 231 deg. F. 5: Max temp 221K, -80 F Min temp 36K, -394 F * Operating temp : < 50K (-370 deg. F) INSTRUMENTS - Near Infrared Camera (NIRCam) - Near Infrared Spectrograph (NIRSpec) - Mid Infrared Instrument (MIRI) - Fine Guidance Sensors/Near Infrared Imager & Slitless Spectrograph (FGS/NIRISS) TRAJECTORY MCC1A (65-minute engine burn) began 2021-Dec-26 12:50 UTC, completed 01:55 UTC. MCC1B (09:27 engine burn) began 2021-Dec-28 00:20 UTC, completed 00:29:27 UTC. MCC2 (04:57 engine burn) began 2022-Jan-24 19:00 UTC, completed 19:04:57 UTC. Concatenation of reconstructed trajectory solutions (as-flown) from Goddard Flight Dynamics Facility (FDF), based on tracking data through November 3, with prediction thereafter. Trajectory files Start (TDB) End (TDB) ---------------------------------------- ----------------- ----------------- DEFINITIVE_EPHEMERIS_202135913-2024301 2021-Dec-25 13:01 2024-Nov-04 00:01 28D_BURN_PREDICT_SK_2024309000000_01U 2024-Nov-04 00:01 2024-Dec-02 00:01 5Y_SCHEDULE_2024309000000_01U.V0.1 2024-Dec-02 00:01 2029-Nov-03 23:59 ******************************************************************************* ******************************************************************************* Ephemeris / API_USER Thu Nov 7 14:29:12 2024 Pasadena, USA / Horizons ******************************************************************************* Target body name: James Webb Space Telescope (spacecraft) (-170) {source: JWST_merged} Center body name: Earth (399) {source: DE441} Center-site name: iTelescope Obs., Siding Spring ******************************************************************************* 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 : 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.241106.p250201 EOP coverage : DATA-BASED 1962-JAN-20 TO 2024-NOV-06. PREDICTS-> 2025-JAN-31 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 .....< 2024-Oct-31 11:00 04 28 03.76 +23 36 12.2 61.222975 1.111660 n.a. n.a. 1.001385857789 -0.3582490 0.01007493027995 -0.2507222 149.0895 /L 30.6145 136.9/ 1.1660 n.a. n.a. 1.7158051 74.189985 -50.18933 2024-Oct-31 11:10 04 28 04.91 +23 36 16.8 59.885429 2.973177 n.a. n.a. 1.001384421026 -0.3582059 0.01007393443084 -0.2457826 149.0919 /L 30.6121 137.0/ 1.1471 n.a. n.a. 1.5801942 73.472374 -51.94066 2024-Oct-31 11:20 04 28 05.97 +23 36 21.2 58.510713 4.809608 n.a. n.a. 1.001382984436 -0.3581628 0.01007295970732 -0.2401888 149.0947 /L 30.6094 137.1/ 1.1283 n.a. n.a. 1.4461096 72.733532 -53.75369 2024-Oct-31 11:30 04 28 06.92 +23 36 25.5 57.096286 6.619154 n.a. n.a. 1.001381548019 -0.3581197 0.01007200871273 -0.2339512 149.0979 /L 30.6062 137.2/ 1.1095 n.a. n.a. 1.3137637 71.971324 -55.63854 2024-Oct-31 11:40 04 28 07.78 +23 36 29.4 55.639562 8.399886 n.a. n.a. 1.001380111775 -0.3580766 0.01007108400622 -0.2270814 149.1014 /L 30.6027 137.3/ 1.0907 n.a. n.a. 1.1833635 71.183147 -57.60763 2024-Oct-31 11:50 04 28 08.55 +23 36 33.1 54.137917 10.149740 n.a. n.a. 1.001378675704 -0.3580335 0.01007018809782 -0.2195923 149.1054 /L 30.5989 137.4/ 1.0721 n.a. n.a. 1.0551099 70.365712 -59.67622 2024-Oct-31 12:00 04 28 09.23 +23 36 36.6 52.588695 11.866510 n.a. n.a. 1.001377239806 -0.3579904 0.01006932344350 -0.2114979 149.1096 /L 30.5947 137.5/ 1.0535 n.a. n.a. 0.9291971 69.514673 -61.86326 2024-Oct-31 12:10 04 28 09.82 +23 36 39.7 50.989232 13.547840 n.a. n.a. 1.001375804080 -0.3579473 0.01006849244052 -0.2028135 149.1142 /L 30.5901 137.6/ 1.0350 n.a. n.a. 0.8058122 68.623946 -64.19252 2024-Oct-31 12:20 04 28 10.32 +23 36 42.5 49.336869 15.191214 n.a. n.a. 1.001374368528 -0.3579042 0.01006769742270 -0.1935555 149.1192 /L 30.5852 137.7/ 1.0165 n.a. n.a. 0.6851340 67.684390 -66.69413 2024-Oct-31 12:30 04 28 10.74 +23 36 44.9 47.628986 16.793957 n.a. n.a. 1.001372933148 -0.3578611 0.01006694065591 -0.1837413 149.1245 /L 30.5800 137.8/ 0.9982 n.a. n.a. 0.5673334 66.680988 -69.40660 2024-Oct-31 12:40 04 28 11.08 +23 36 47.0 45.863031 18.353225 n.a. n.a. 1.001371497942 -0.3578180 0.01006622433365 -0.1733896 149.1301 /L 30.5744 137.9/ 0.9801 n.a. n.a. 0.4525720 65.586079 -72.37972 2024-Oct-31 12:50 04 28 11.34 +23 36 48.7 44.036565 19.866006 n.a. n.a. 1.001370062909 -0.3577748 0.01006555057275 -0.1625200 149.1361 /L 30.5686 138.0/ 0.9620 n.a. n.a. 0.3410038 64.340195 -75.67839 2024-Oct-31 13:00 04 28 11.53 +23 36 49.9 42.147308 21.329118 n.a. n.a. 1.001368628048 -0.3577317 0.01006492140930 -0.1511531 149.1423 /L 30.5624 138.2/ 0.9441 n.a. n.a. 0.2327779 62.782295 -79.38776 2024-Oct-31 13:10 04 28 11.64 +23 36 50.8 40.193197 22.739215 n.a. n.a. 1.001367193360 -0.3576886 0.01006433879462 -0.1393105 149.1488 /L 30.5559 138.3/ 0.9263 n.a. n.a. 0.1280652 60.251260 -83.61873 2024-Oct-31 13:20 04 28 11.69 +23 36 51.2 38.172458 24.092794 n.a. n.a. 1.001365758846 -0.3576455 0.01006380459149 -0.1270148 149.1557 /L 30.5492 138.4/ 0.9088 n.a. n.a. 0.0276568 46.653176 -88.48267 2024-Oct-31 13:30 04 28 11.67 +23 36 51.2 36.083673 25.386207 n.a. n.a. 1.001364324504 -0.3576024 0.01006332057038 -0.1142895 149.1627 /L 30.5422 138.5/ 0.8913 n.a. n.a. 0.0714008 247.66556 -85.65417 2024-Oct-31 13:40 04 28 11.59 +23 36 50.7 33.925868 26.615678 n.a. n.a. 1.001362890336 -0.3575592 0.01006288840608 -0.1011587 149.1701 /L 30.5349 138.6/ 0.8741 n.a. n.a. 0.1650012 243.07480 -78.77807 2024-Oct-31 13:50 04 28 11.46 +23 36 49.7 31.698597 27.777332 n.a. n.a. 1.001361456340 -0.3575161 0.01006250967440 -0.0876477 149.1777 /L 30.5274 138.7/ 0.8570 n.a. n.a. 0.2549479 240.98084 -70.51639 2024-Oct-31 14:00 04 28 11.27 +23 36 48.2 29.402038 28.867219 n.a. n.a. 1.001360022518 -0.3574730 0.01006218584904 -0.0737822 149.1855 /L 30.5197 138.8/ 0.8402 n.a. n.a. 0.3410505 239.34027 -60.65541 2024-Oct-31 14:10 04 28 11.04 +23 36 46.2 27.037080 29.881360 n.a. n.a. 1.001358588868 -0.3574299 0.01006191829866 -0.0595887 149.1935 /L 30.5118 138.9/ 0.8235 n.a. n.a. 0.4232510 237.83259 -49.17818 2024-Oct-31 14:20 04 28 10.75 +23 36 43.6 24.605411 30.815791 n.a. n.a. 1.001357155392 -0.3573867 0.01006170828427 -0.0450944 149.2017 /L 30.5036 139.1/ 0.8071 n.a. n.a. 0.5015246 236.35855 -36.47776 2024-Oct-31 14:30 04 28 10.43 +23 36 40.6 22.109592 31.666614 n.a. n.a. 1.001355722089 -0.3573436 0.01006155695667 -0.0303272 149.2101 /L 30.4953 139.2/ 0.7908 n.a. n.a. 0.5758700 234.87576 -23.41662 2024-Oct-31 14:40 04 28 10.07 +23 36 37.0 19.553121 32.430064 n.a. n.a. 1.001354288958 -0.3573005 0.01006146535423 -0.0153152 149.2187 /L 30.4868 139.3/ 0.7748 n.a. n.a. 0.6463080 233.36186 -11.02947 2024-Oct-31 14:50 04 28 09.68 +23 36 32.8 16.940465 33.102569 n.a. n.a. 1.001352856001 -0.3572574 0.01006143440075 -0.0000873 149.2274 /L 30.4781 139.4/ 0.7590 n.a. n.a. 0.7128824 231.80294 -0.062018 2024-Oct-31 15:00 04 28 09.26 +23 36 28.1 14.277069 33.680826 n.a. n.a. 1.001351423217 -0.3572142 0.01006146490373 0.0153273 149.2362 /L 30.4694 139.5/ 0.7435 n.a. n.a. 0.7756605 230.18919 9.2242817 2024-Oct-31 15:10 04 28 08.81 +23 36 22.9 11.569329 34.161865 n.a. n.a. 1.001349990605 -0.3571711 0.01006155755274 0.0308990 149.2452 /L 30.4605 139.6/ 0.7282 n.a. n.a. 0.8347345 228.51291 16.924114 2024-Oct-31 15:20 04 28 08.35 +23 36 17.0 8.824522 34.543123 n.a. n.a. 1.001348558167 -0.3571280 0.01006171291798 0.0465979 149.2543 /L 30.4515 139.7/ 0.7132 n.a. n.a. 0.8902228 226.76767 23.282370 2024-Oct-31 15:30 04 28 07.87 +23 36 10.6 6.050707 34.822503 n.a. n.a. 1.001347125902 -0.3570849 0.01006193144929 0.0623939 149.2635 /L 30.4424 139.8/ 0.6984 n.a. n.a. 0.9422714 224.94782 28.561760 2024-Oct-31 15:40 04 28 07.39 +23 36 03.7 3.256572 34.998435 n.a. n.a. 1.001345693810 -0.3570418 0.01006221347515 0.0782566 149.2727 /L 30.4332 140.0/ 0.6838 n.a. n.a. 0.9910547 223.04830 32.989025 2024-Oct-31 15:50 04 28 06.89 +23 35 56.1 0.451267 35.069910 n.a. n.a. 1.001344261890 -0.3569987 0.01006255920203 0.0941555 149.2820 /L 30.4240 140.1/ 0.6696 n.a. n.a. 1.0367770 221.06454 36.743536 2024-Oct-31 16:00 t 04 28 06.40 +23 35 48.0 357.644194 35.036516 n.a. n.a. 1.001342830144 -0.3569556 0.01006296871404 0.1100602 149.2913 /L 30.4147 140.2/ 0.6555 n.a. n.a. 1.0796731 218.99252 39.962064 2024-Oct-31 16:10 04 28 05.91 +23 35 39.3 354.844798 34.898443 n.a. n.a. 1.001341398571 -0.3569125 0.01006344197269 0.1259399 149.3007 /L 30.4054 140.3/ 0.6418 n.a. n.a. 1.1200093 216.82875 42.747478 2024-Oct-31 16:20 04 28 05.43 +23 35 30.0 352.062344 34.656483 n.a. n.a. 1.001339967170 -0.3568694 0.01006397881699 0.1417643 149.3100 /L 30.3962 140.4/ 0.6283 n.a. n.a. 1.1580835 214.57051 45.176952 2024-Oct-31 16:30 04 28 04.96 +23 35 20.2 349.305710 34.312005 n.a. n.a. 1.001338535943 -0.3568263 0.01006457896382 0.1575028 149.3193 /L 30.3869 140.5/ 0.6151 n.a. n.a. 1.1942245 212.21587 47.308557 2024-Oct-31 16:40 04 28 04.51 +23 35 09.8 346.583204 33.866919 n.a. n.a. 1.001337104888 -0.3567831 0.01006524200837 0.1731254 149.3286 /L 30.3777 140.6/ 0.6022 n.a. n.a. 1.2287918 209.76397 49.186216 2024-Oct-31 16:50 04 28 04.08 +23 34 58.8 343.902401 33.323621 n.a. n.a. 1.001335674007 -0.3567400 0.01006596742503 0.1886019 149.3379 /L 30.3685 140.7/ 0.5895 n.a. n.a. 1.2621731 207.21515 50.843366 2024-Oct-31 17:00 04 28 03.67 +23 34 47.3 341.270028 32.684940 n.a. n.a. 1.001334243298 -0.3566969 0.01006675456839 0.2039026 149.3471 /L 30.3594 140.8/ 0.5771 n.a. n.a. 1.2947819 204.57119 52.305632 2024-Oct-31 17:10 04 28 03.30 +23 34 35.3 338.691882 31.954065 n.a. n.a. 1.001332812763 -0.3566538 0.01006760267452 0.2189982 149.3561 /L 30.3503 140.9/ 0.5650 n.a. n.a. 1.3270536 201.83545 53.592799 2024-Oct-31 17:20 04 28 02.96 +23 34 22.7 336.172787 31.134477 n.a. n.a. 1.001331382400 -0.3566107 0.01006851086245 0.2338596 149.3651 /L 30.3414 141.0/ 0.5532 n.a. n.a. 1.3594405 199.01307 54.720285 2024-Oct-31 17:30 04 28 02.66 +23 34 09.6 333.716589 30.229878 n.a. n.a. 1.001329952210 -0.3565676 0.01006947813593 0.2484585 149.3740 /L 30.3326 141.1/ 0.5417 n.a. n.a. 1.3924051 196.11105 55.700242 2024-Oct-31 17:40 A 04 28 02.40 +23 33 55.9 331.326185 29.244122 n.a. n.a. 1.001328522194 -0.3565245 0.01007050338540 0.2627667 149.3827 /L 30.3239 141.2/ 0.5304 n.a. n.a. 1.4264134 193.13829 56.542407 2024-Oct-31 17:50 A 04 28 02.20 +23 33 41.8 329.003571 28.181157 n.a. n.a. 1.001327092350 -0.3564814 0.01007158539014 0.2767569 149.3913 /L 30.3154 141.3/ 0.5194 n.a. n.a. 1.4619262 190.10551 57.254757 2024-Oct-31 18:00 A 04 28 02.04 +23 33 27.1 326.749917 27.044961 n.a. n.a. 1.001325662679 -0.3564383 0.01007272282069 0.2904023 149.3997 /L 30.3070 141.4/ 0.5087 n.a. n.a. 1.4993899 187.02513 57.844021 2024-Oct-31 18:10 A 04 28 01.94 +23 33 12.0 324.565645 25.839498 n.a. n.a. 1.001324233181 -0.3563952 0.01007391424148 0.3036767 149.4080 /L 30.2988 141.5/ 0.4982 n.a. n.a. 1.5392278 183.91098 58.316079 2024-Oct-31 18:20 N 04 28 01.89 +23 32 56.4 322.450525 24.568676 n.a. n.a. 1.001322803856 -0.3563521 0.01007515811361 0.3165548 149.4160 /L 30.2908 141.6/ 0.4880 n.a. n.a. 1.5818309 180.77794 58.676267 2024-Oct-31 18:30 N 04 28 01.91 +23 32 40.4 320.403762 23.236309 n.a. n.a. 1.001321374704 -0.3563090 0.01007645279793 0.3290119 149.4239 /L 30.2830 141.7/ 0.4781 n.a. n.a. 1.6275495 177.64149 58.929612 2024-Oct-31 18:40 Nm 04 28 02.00 +23 32 23.9 318.424087 21.846095 n.a. n.a. 1.001319945725 -0.3562659 0.01007779655818 0.3410243 149.4315 /L 30.2754 141.8/ 0.4685 n.a. n.a. 1.6766865 174.51725 59.080991 2024-Oct-31 18:50 Cm 04 28 02.15 +23 32 07.0 316.509841 20.401590 n.a. n.a. 1.001318516919 -0.3562228 0.01007918756445 0.3525690 149.4388 /L 30.2681 141.9/ 0.4591 n.a. n.a. 1.7294921 171.42047 59.135246 2024-Oct-31 19:00 Cm 04 28 02.38 +23 31 49.7 314.659054 18.906200 n.a. n.a. 1.001317088285 -0.3561797 0.01008062389675 0.3636241 149.4459 /L 30.2610 142.0/ 0.4500 n.a. n.a. 1.7861600 168.36557 59.097239 >..... Daylight Cut-off Requested .....< >..... Elevation Cut-off Requested .....< $$EOE *************************************************************************************************************************************************************************************************************************************************** Column meaning: TIME Times PRIOR to 1962 are UT1, a mean-solar time closely related to the prior but now-deprecated GMT. Times AFTER 1962 are in UTC, the current civil or "wall-clock" time-scale. UTC is kept within 0.9 seconds of UT1 using integer leap-seconds for 1972 and later years. Conversion from the internal Barycentric Dynamical Time (TDB) of solar system dynamics to the non-uniform civil UT time-scale requested for output has not been determined for UTC times after the next July or January 1st. Therefore, the last known leap-second is used as a constant over future intervals. Time tags refer to the UT time-scale conversion from TDB on Earth regardless of observer location within the solar system, although clock rates may differ due to the local gravity field and no analog to "UT" may be defined for that location. Any 'b' symbol in the 1st-column denotes a B.C. date. First-column blank (" ") denotes an A.D. date. CALENDAR SYSTEM Mixed calendar mode was active such that calendar dates after AD 1582-Oct-15 (if any) are in the modern Gregorian system. Dates prior to 1582-Oct-5 (if any) are in the Julian calendar system, which is automatically extended for dates prior to its adoption on 45-Jan-1 BC. The Julian calendar is useful for matching historical dates. The Gregorian calendar more accurately corresponds to the Earth's orbital motion and seasons. A "Gregorian-only" calendar mode is available if such physical events are the primary interest. NOTE: "n.a." in output means quantity "not available" at the print-time. SOLAR PRESENCE (OBSERVING SITE) Time tag is followed by a blank, then a solar-presence condition code: '*' Daylight (refracted solar upper-limb on or above apparent horizon) 'C' Civil twilight/dawn 'N' Nautical twilight/dawn 'A' Astronomical twilight/dawn ' ' Night OR geocentric ephemeris LUNAR PRESENCE WITH TARGET RISE/TRANSIT/SET EVENT MARKER (OBSERVING SITE) The solar-presence code column is immediately followed by another marker: 'm' Refracted upper-limb of Moon on or above apparent horizon ' ' Refracted upper-limb of Moon below apparent horizon OR geocentric The lunar presence marker (an ongoing state) can be over-ridden by a target event marker if an event has occurred since the last output step: 'r' Rise (target body on or went above cut-off RTS elevation) 'e' Elevation max (target body maximum elevation angle has occurred) 't' Transit (target body at or passed through observer meridian) 's' Set (target body on or went below cut-off RTS elevation) RTS MARKERS (TVH) Rise and set are with respect to the reference ellipsoid true visual horizon defined by the elevation cut-off angle. Horizon dip and yellow-light refraction (Earth only) are considered. Accuracy is < or = to twice the requested search step-size. 'R.A._____(ICRF)_____DEC' = Astrometric right ascension and declination of the target center with respect to the observing site (coordinate origin) in the reference frame of the planetary ephemeris (ICRF). Compensated for down-leg light-time delay aberration. Units: RA in hours-minutes-seconds of time, HH MM SS.ff{ffff} DEC in degrees-minutes-seconds of arc, sDD MN SC.f{ffff} 'Azi____(a-app)___Elev' = Airless apparent azimuth and elevation of target center. Compensated for light-time, the gravitational deflection of light, stellar aberration, precession and nutation. Azimuth is measured clockwise from north: North(0) -> East(90) -> South(180) -> West(270) -> North (360) Elevation angle is with respect to a plane perpendicular to the reference surface local zenith direction. TOPOCENTRIC ONLY. Units: DEGREES 'APmag S-brt' = The targets' approximate apparent visual magnitude and surface brightness. For planets and natural satellites, output is restricted to solar phase angles covered by observational data. Outside the observed phase angle range, "n.a." may be output to avoid extrapolation beyond the limit of model validity. For Earth-based observers, the estimated dimming due to atmospheric absorption (extinction) is available as a separate, requestable quantity. Surface brightness is the average airless visual magnitude of a square-arcsecond of the illuminated portion of the apparent disk. It is computed only if the target radius is known. Units: MAGNITUDES & MAGNITUDES PER SQUARE ARCSECOND 'r rdot' = The Sun's apparent range ("r", light-time aberrated) and range-rate ("rdot") relative to the target center, as seen by the observer. A positive "rdot" means the target center was moving away from the Sun, negative means moving toward the Sun. Units: AU and KM/S 'delta deldot' = Apparent range ("delta", light-time aberrated) and range-rate ("delta-dot") of the target center relative to the observer. A positive "deldot" means the target center is moving away from the observer, negative indicates movement toward the observer. Units: AU and KM/S 'S-O-T /r' = Sun-Observer-Target apparent SOLAR ELONGATION ANGLE seen from the observers' location at print-time. The '/r' column provides a code indicating the targets' apparent position relative to the Sun in the observers' sky, as described below: Case A: For an observing location on the surface of a rotating body, that body rotational sense is considered: /T indicates target TRAILS Sun (evening sky: rises and sets AFTER Sun) /L indicates target LEADS Sun (morning sky: rises and sets BEFORE Sun) Case B: For an observing point that does not have a rotational model (such as a spacecraft), the "leading" and "trailing" condition is defined by the observers' heliocentric ORBITAL motion: * If continuing in the observers' current direction of heliocentric motion would encounter the targets' apparent longitude first, followed by the Sun's, the target LEADS the Sun as seen by the observer. * If the Sun's apparent longitude would be encountered first, followed by the targets', the target TRAILS the Sun. Two other codes can be output: /* indicates observer is Sun-centered (undefined) /? Target is aligned with Sun center (no lead or trail) The S-O-T solar elongation angle is numerically the minimum separation angle of the Sun and target in the sky in any direction. It does NOT indicate the amount of separation in the leading or trailing directions, which would be defined along the equator of a spherical coordinate system. Units: DEGREES 'S-T-O' = The Sun-Target-Observer angle; the interior vertex angle at target center formed by a vector from the target to the apparent center of the Sun (at reflection time on the target) and the apparent vector from target to the observer at print-time. Slightly different from true PHASE ANGLE (requestable separately) at the few arcsecond level in that it includes stellar aberration on the down-leg from target to observer. Units: DEGREES 'T-O-M/MN_Illu%' = Target-Observer-Moon LUNAR ELONGATION angle and illuminated percentage. The apparent lunar elongation angle between target body center and Moon center, seen from the observing site, along with fraction of the lunar disk illuminated by the Sun. A negative lunar elongation angle indicates the target center is behind the Moon. Units: DEGREES & PERCENT 'RA_3sigma DEC_3sigma' = Uncertainty in Right-Ascension and Declination. Output values are the formal +/- 3 standard-deviations (sigmas) around nominal position. Units: ARCSECONDS 'Sky_motion Sky_mot_PA RelVel-ANG' = Total apparent angular rate of the target in the plane-of-sky. "Sky_mot_PA" is the position angle of the target's direction of motion in the plane-of-sky, measured counter-clockwise from the apparent of-date north pole direction. "RelVel-ANG" is the flight path angle of the target's relative motion with respect to the observer's line-of-sight, in the range [-90,+90], where positive values indicate motion away from the observer, negative values are toward the observer: -90 = target is moving directly toward the observer 0 = target is moving at right angles to the observer's line-of-sight +90 = target is moving directly away from the observer UNITS: ARCSECONDS/MINUTE, DEGREES, DEGREES Computations by ... Solar System Dynamics Group, Horizons On-Line Ephemeris System 4800 Oak Grove Drive, Jet Propulsion Laboratory Pasadena, CA 91109 USA General site: https://ssd.jpl.nasa.gov/ Mailing list: https://ssd.jpl.nasa.gov/email_list.html System news : https://ssd.jpl.nasa.gov/horizons/news.html User Guide : https://ssd.jpl.nasa.gov/horizons/manual.html Connect : browser https://ssd.jpl.nasa.gov/horizons/app.html#/x API https://ssd-api.jpl.nasa.gov/doc/horizons.html command-line telnet ssd.jpl.nasa.gov 6775 e-mail/batch https://ssd.jpl.nasa.gov/ftp/ssd/hrzn_batch.txt scripts https://ssd.jpl.nasa.gov/ftp/ssd/SCRIPTS Author : Jon.D.Giorgini@jpl.nasa.gov ***************************************************************************************************************************************************************************************************************************************************