4, 2019-04-14 04:45

Object Data Page

Results

******************************************************************************* Ephemeris / WWW_USER Thu May 2 11:07:57 2019 Pasadena, USA / Horizons ******************************************************************************* Target body name: 99942 Apophis (2004 MN4) {source: JPL#199} Center body name: Earth (399) {source: DE431} Center-site name: GEOCENTRIC ******************************************************************************* Start time : A.D. 2029-Apr-14 04:00:00.0000 UT Stop time : A.D. 2029-Apr-14 06:00:00.0000 UT Step-size : 1 minutes ******************************************************************************* Target pole/equ : No model available Target radii : 0.2 km Center geodetic : 0.00000000,0.00000000,0.0000000 {E-lon(deg),Lat(deg),Alt(km)} Center cylindric: 0.00000000,0.00000000,0.0000000 {E-lon(deg),Dxy(km),Dz(km)} Center pole/equ : High-precision EOP model {East-longitude positive} Center radii : 6378.1 x 6378.1 x 6356.8 km {Equator, meridian, pole} Target primary : Sun Vis. interferer : MOON (R_eq= 1737.400) km {source: DE431} Rel. light bend : Sun, EARTH {source: DE431} Rel. lght bnd GM: 1.3271E+11, 3.9860E+05 km^3/s^2 Small-body perts: Yes {source: SB431-N16} Atmos refraction: NO (AIRLESS) RA format : HMS Time format : CAL EOP file : eop.190501.p190723 EOP coverage : DATA-BASED 1962-JAN-20 TO 2019-MAY-01. PREDICTS-> 2019-JUL-22 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 ) ******************************************************************************* Initial IAU76/J2000 heliocentric ecliptic osculating elements (au, days, deg.): EPOCH= 2454733.5 ! 2008-Sep-24.00 (TDB) Residual RMS= .17383 EC= .1911953048308701 QR= .7460724295867941 TP= 2454894.9125195034 OM= 204.4460289189818 W= 126.401879524849 IN= 3.331369520013644 Equivalent ICRF heliocentric equatorial cartesian coordinates (au, au/d): X=-9.617610121438336E-01 Y= 5.056402470928835E-01 Z= 1.634216613600531E-01 VX=-7.112764893524261E-03 VY=-1.205930258845442E-02 VZ=-4.668804545027994E-03 Asteroid physical parameters (km, seconds, rotational period in hours): GM= n.a. RAD= .1625 ROTPER= 30.4 H= 19.7 G= .250 B-V= n.a. ALBEDO= .230 STYP= Sq Asteroid non-gravitational force model (AMRAT= m^2/kg;A1,A2,A3=au/d^2;R0=au): AMRAT= 0. A1= 0. A2= -5.592839897872E-14 A3= 0. Non-standard or simulated/proxy model: ALN= 1. NK= 0. NM= 2. NN= 5.093 R0= 1. ************************************************************************************************************** Date__(UT)__HR:MN R.A._(ICRF/J2000.0)_DEC APmag S-brt delta deldot S-O-T /r S-T-O ************************************************************************************************************** $$SOE 2029-Apr-14 04:00 01 38 57.14 +26 26 10.6 17. 11. 0.00099691672192 5.9946093 17.2480 /T 162.7352 2029-Apr-14 04:01 01 38 47.14 +26 24 51.9 17. 11. 0.00099932107095 5.9949575 17.2208 /T 162.7624 2029-Apr-14 04:02 01 38 37.19 +26 23 33.6 17. 11. 0.00100172555844 5.9953007 17.1938 /T 162.7894 2029-Apr-14 04:03 01 38 27.29 +26 22 15.6 17. 11. 0.00100413018238 5.9956389 17.1670 /T 162.8162 2029-Apr-14 04:04 01 38 17.45 +26 20 57.9 17. 11. 0.00100653494079 5.9959721 17.1404 /T 162.8428 2029-Apr-14 04:05 01 38 07.65 +26 19 40.6 17. 11. 0.00100893983171 5.9963005 17.1140 /T 162.8692 2029-Apr-14 04:06 01 37 57.91 +26 18 23.5 17. 11. 0.00101134485321 5.9966241 17.0877 /T 162.8954 2029-Apr-14 04:07 01 37 48.21 +26 17 06.8 17. 11. 0.00101375000337 5.9969430 17.0617 /T 162.9214 2029-Apr-14 04:08 01 37 38.56 +26 15 50.5 17. 11. 0.00101615528030 5.9972572 17.0358 /T 162.9473 2029-Apr-14 04:09 01 37 28.97 +26 14 34.4 17. 11. 0.00101856068215 5.9975668 17.0102 /T 162.9729 2029-Apr-14 04:10 01 37 19.42 +26 13 18.7 17. 11. 0.00102096620706 5.9978718 16.9847 /T 162.9984 2029-Apr-14 04:11 01 37 09.92 +26 12 03.3 17. 11. 0.00102337185322 5.9981722 16.9594 /T 163.0237 2029-Apr-14 04:12 01 37 00.47 +26 10 48.2 17. 11. 0.00102577761882 5.9984682 16.9342 /T 163.0488 2029-Apr-14 04:13 01 36 51.06 +26 09 33.4 17. 11. 0.00102818350208 5.9987598 16.9093 /T 163.0737 2029-Apr-14 04:14 01 36 41.71 +26 08 18.9 17. 11. 0.00103058950125 5.9990471 16.8845 /T 163.0985 2029-Apr-14 04:15 01 36 32.40 +26 07 04.7 17. 11. 0.00103299561459 5.9993300 16.8599 /T 163.1231 2029-Apr-14 04:16 01 36 23.13 +26 05 50.9 17. 11. 0.00103540184038 5.9996087 16.8355 /T 163.1475 2029-Apr-14 04:17 01 36 13.91 +26 04 37.3 17. 11. 0.00103780817693 5.9998831 16.8113 /T 163.1717 2029-Apr-14 04:18 01 36 04.74 +26 03 24.1 17. 11. 0.00104021462256 6.0001534 16.7872 /T 163.1958 2029-Apr-14 04:19 01 35 55.62 +26 02 11.1 17. 11. 0.00104262117561 6.0004197 16.7633 /T 163.2196 2029-Apr-14 04:20 01 35 46.54 +26 00 58.5 17. 11. 0.00104502783444 6.0006818 16.7396 /T 163.2434 2029-Apr-14 04:21 01 35 37.50 +25 59 46.1 17. 11. 0.00104743459744 6.0009399 16.7160 /T 163.2669 2029-Apr-14 04:22 01 35 28.51 +25 58 34.1 17. 11. 0.00104984146301 6.0011941 16.6926 /T 163.2903 2029-Apr-14 04:23 01 35 19.56 +25 57 22.3 17. 11. 0.00105224842956 6.0014443 16.6694 /T 163.3135 2029-Apr-14 04:24 01 35 10.66 +25 56 10.8 17. 11. 0.00105465549554 6.0016907 16.6463 /T 163.3365 2029-Apr-14 04:25 01 35 01.80 +25 54 59.7 17. 11. 0.00105706265940 6.0019332 16.6234 /T 163.3594 2029-Apr-14 04:26 01 34 52.98 +25 53 48.8 17. 11. 0.00105946991962 6.0021720 16.6007 /T 163.3821 2029-Apr-14 04:27 01 34 44.21 +25 52 38.2 17. 11. 0.00106187727469 6.0024070 16.5781 /T 163.4047 2029-Apr-14 04:28 01 34 35.47 +25 51 27.9 17. 11. 0.00106428472311 6.0026383 16.5557 /T 163.4271 2029-Apr-14 04:29 01 34 26.79 +25 50 17.8 17. 11. 0.00106669226343 6.0028660 16.5334 /T 163.4493 2029-Apr-14 04:30 01 34 18.14 +25 49 08.1 17. 11. 0.00106909989417 6.0030901 16.5113 /T 163.4714 2029-Apr-14 04:31 01 34 09.53 +25 47 58.6 17. 11. 0.00107150761390 6.0033106 16.4894 /T 163.4934 2029-Apr-14 04:32 01 34 00.97 +25 46 49.5 17. 11. 0.00107391542120 6.0035275 16.4676 /T 163.5151 2029-Apr-14 04:33 01 33 52.45 +25 45 40.6 17. 11. 0.00107632331466 6.0037410 16.4460 /T 163.5367 2029-Apr-14 04:34 01 33 43.96 +25 44 31.9 17. 11. 0.00107873129290 6.0039510 16.4245 /T 163.5582 2029-Apr-14 04:35 01 33 35.52 +25 43 23.6 17. 11. 0.00108113935453 6.0041577 16.4032 /T 163.5795 2029-Apr-14 04:36 01 33 27.12 +25 42 15.5 17. 11. 0.00108354749821 6.0043609 16.3820 /T 163.6007 2029-Apr-14 04:37 01 33 18.76 +25 41 07.7 17. 11. 0.00108595572260 6.0045609 16.3609 /T 163.6217 2029-Apr-14 04:38 01 33 10.44 +25 40 00.2 17. 11. 0.00108836402635 6.0047575 16.3401 /T 163.6426 2029-Apr-14 04:39 01 33 02.15 +25 38 52.9 17. 11. 0.00109077240818 6.0049509 16.3193 /T 163.6633 2029-Apr-14 04:40 01 32 53.91 +25 37 45.9 18. 11. 0.00109318086677 6.0051411 16.2987 /T 163.6839 2029-Apr-14 04:41 01 32 45.71 +25 36 39.2 18. 11. 0.00109558940084 6.0053281 16.2783 /T 163.7043 2029-Apr-14 04:42 01 32 37.54 +25 35 32.7 18. 11. 0.00109799800914 6.0055120 16.2580 /T 163.7246 2029-Apr-14 04:43 01 32 29.41 +25 34 26.5 18. 11. 0.00110040669041 6.0056927 16.2378 /T 163.7447 2029-Apr-14 04:44 01 32 21.32 +25 33 20.6 18. 11. 0.00110281544342 6.0058704 16.2178 /T 163.7648 2029-Apr-14 04:45 01 32 13.27 +25 32 14.9 18. 11. 0.00110522426693 6.0060451 16.1979 /T 163.7846 2029-Apr-14 04:46 01 32 05.25 +25 31 09.5 18. 11. 0.00110763315975 6.0062167 16.1782 /T 163.8043 2029-Apr-14 04:47 01 31 57.28 +25 30 04.3 18. 11. 0.00111004212067 6.0063854 16.1586 /T 163.8239 2029-Apr-14 04:48 01 31 49.34 +25 28 59.4 18. 11. 0.00111245114851 6.0065512 16.1391 /T 163.8434 2029-Apr-14 04:49 01 31 41.43 +25 27 54.7 18. 11. 0.00111486024212 6.0067141 16.1198 /T 163.8627 2029-Apr-14 04:50 01 31 33.56 +25 26 50.3 18. 11. 0.00111726940032 6.0068741 16.1006 /T 163.8819 2029-Apr-14 04:51 01 31 25.73 +25 25 46.2 18. 11. 0.00111967862199 6.0070313 16.0815 /T 163.9009 2029-Apr-14 04:52 01 31 17.94 +25 24 42.3 18. 11. 0.00112208790598 6.0071856 16.0626 /T 163.9198 2029-Apr-14 04:53 01 31 10.18 +25 23 38.6 18. 11. 0.00112449725120 6.0073372 16.0438 /T 163.9386 2029-Apr-14 04:54 01 31 02.45 +25 22 35.2 18. 11. 0.00112690665653 6.0074861 16.0251 /T 163.9572 2029-Apr-14 04:55 01 30 54.76 +25 21 32.0 18. 11. 0.00112931612088 6.0076323 16.0066 /T 163.9758 2029-Apr-14 04:56 01 30 47.11 +25 20 29.1 18. 11. 0.00113172564318 6.0077758 15.9882 /T 163.9941 2029-Apr-14 04:57 01 30 39.49 +25 19 26.4 18. 11. 0.00113413522236 6.0079166 15.9699 /T 164.0124 2029-Apr-14 04:58 01 30 31.91 +25 18 24.0 18. 11. 0.00113654485736 6.0080549 15.9518 /T 164.0305 2029-Apr-14 04:59 01 30 24.36 +25 17 21.8 18. 11. 0.00113895454716 6.0081905 15.9337 /T 164.0485 2029-Apr-14 05:00 01 30 16.84 +25 16 19.8 18. 11. 0.00114136429070 6.0083236 15.9158 /T 164.0664 2029-Apr-14 05:01 01 30 09.36 +25 15 18.1 18. 11. 0.00114377408699 6.0084542 15.8981 /T 164.0842 2029-Apr-14 05:02 01 30 01.91 +25 14 16.6 18. 11. 0.00114618393500 6.0085823 15.8804 /T 164.1018 2029-Apr-14 05:03 01 29 54.49 +25 13 15.4 18. 11. 0.00114859383376 6.0087079 15.8629 /T 164.1193 2029-Apr-14 05:04 01 29 47.11 +25 12 14.3 18. 11. 0.00115100378226 6.0088311 15.8455 /T 164.1367 2029-Apr-14 05:05 01 29 39.76 +25 11 13.6 18. 11. 0.00115341377955 6.0089518 15.8282 /T 164.1540 2029-Apr-14 05:06 01 29 32.44 +25 10 13.0 18. 11. 0.00115582382465 6.0090702 15.8110 /T 164.1711 2029-Apr-14 05:07 01 29 25.16 +25 09 12.7 18. 11. 0.00115823391662 6.0091862 15.7940 /T 164.1881 2029-Apr-14 05:08 01 29 17.90 +25 08 12.6 18. 11. 0.00116064405451 6.0092999 15.7771 /L 164.2051 2029-Apr-14 05:09 01 29 10.68 +25 07 12.7 18. 11. 0.00116305423741 6.0094113 15.7602 /L 164.2218 2029-Apr-14 05:10 01 29 03.49 +25 06 13.1 18. 11. 0.00116546446438 6.0095204 15.7436 /L 164.2385 2029-Apr-14 05:11 01 28 56.34 +25 05 13.6 18. 11. 0.00116787473452 6.0096272 15.7270 /L 164.2551 2029-Apr-14 05:12 01 28 49.21 +25 04 14.5 18. 11. 0.00117028504693 6.0097318 15.7105 /L 164.2715 2029-Apr-14 05:13 01 28 42.12 +25 03 15.5 18. 11. 0.00117269540073 6.0098342 15.6942 /L 164.2879 2029-Apr-14 05:14 01 28 35.05 +25 02 16.7 18. 11. 0.00117510579503 6.0099344 15.6779 /L 164.3041 2029-Apr-14 05:15 01 28 28.02 +25 01 18.2 18. 11. 0.00117751622896 6.0100325 15.6618 /L 164.3202 2029-Apr-14 05:16 01 28 21.02 +25 00 19.9 18. 11. 0.00117992670167 6.0101285 15.6458 /L 164.3362 2029-Apr-14 05:17 01 28 14.05 +24 59 21.8 18. 11. 0.00118233721231 6.0102223 15.6299 /L 164.3521 2029-Apr-14 05:18 01 28 07.10 +24 58 23.9 18. 11. 0.00118474776004 6.0103141 15.6141 /L 164.3678 2029-Apr-14 05:19 01 28 00.19 +24 57 26.2 18. 11. 0.00118715834403 6.0104038 15.5984 /L 164.3835 2029-Apr-14 05:20 01 27 53.31 +24 56 28.8 18. 11. 0.00118956896346 6.0104914 15.5828 /L 164.3990 2029-Apr-14 05:21 01 27 46.46 +24 55 31.5 18. 11. 0.00119197961751 6.0105771 15.5674 /L 164.4145 2029-Apr-14 05:22 01 27 39.64 +24 54 34.5 18. 11. 0.00119439030538 6.0106607 15.5520 /L 164.4298 2029-Apr-14 05:23 01 27 32.84 +24 53 37.7 18. 11. 0.00119680102629 6.0107424 15.5368 /L 164.4451 2029-Apr-14 05:24 01 27 26.08 +24 52 41.1 18. 11. 0.00119921177944 6.0108221 15.5216 /L 164.4602 2029-Apr-14 05:25 01 27 19.34 +24 51 44.7 18. 11. 0.00120162256406 6.0109000 15.5066 /L 164.4752 2029-Apr-14 05:26 01 27 12.64 +24 50 48.5 18. 11. 0.00120403337938 6.0109759 15.4916 /L 164.4901 2029-Apr-14 05:27 01 27 05.96 +24 49 52.5 18. 11. 0.00120644422465 6.0110499 15.4768 /L 164.5050 2029-Apr-14 05:28 01 26 59.31 +24 48 56.7 18. 11. 0.00120885509911 6.0111221 15.4621 /L 164.5197 2029-Apr-14 05:29 01 26 52.68 +24 48 01.1 18. 11. 0.00121126600202 6.0111924 15.4474 /L 164.5343 2029-Apr-14 05:30 01 26 46.09 +24 47 05.8 18. 11. 0.00121367693265 6.0112609 15.4329 /L 164.5488 2029-Apr-14 05:31 01 26 39.52 +24 46 10.6 18. 11. 0.00121608789028 6.0113276 15.4185 /L 164.5632 2029-Apr-14 05:32 01 26 32.99 +24 45 15.6 18. 11. 0.00121849887418 6.0113926 15.4041 /L 164.5775 2029-Apr-14 05:33 01 26 26.47 +24 44 20.8 18. 11. 0.00122090988364 6.0114557 15.3899 /L 164.5918 2029-Apr-14 05:34 01 26 19.99 +24 43 26.3 18. 11. 0.00122332091798 6.0115172 15.3758 /L 164.6059 2029-Apr-14 05:35 01 26 13.53 +24 42 31.9 18. 11. 0.00122573197648 6.0115769 15.3617 /L 164.6199 2029-Apr-14 05:36 01 26 07.10 +24 41 37.7 18. 11. 0.00122814305847 6.0116349 15.3478 /L 164.6338 2029-Apr-14 05:37 01 26 00.70 +24 40 43.7 18. 11. 0.00123055416327 6.0116912 15.3339 /L 164.6476 2029-Apr-14 05:38 01 25 54.32 +24 39 49.9 18. 11. 0.00123296529021 6.0117459 15.3202 /L 164.6614 2029-Apr-14 05:39 01 25 47.97 +24 38 56.3 18. 11. 0.00123537643862 6.0117989 15.3065 /L 164.6750 2029-Apr-14 05:40 01 25 41.65 +24 38 02.9 18. 11. 0.00123778760785 6.0118503 15.2929 /L 164.6886 2029-Apr-14 05:41 01 25 35.35 +24 37 09.7 18. 11. 0.00124019879726 6.0119001 15.2795 /L 164.7020 2029-Apr-14 05:42 01 25 29.08 +24 36 16.7 18. 11. 0.00124261000619 6.0119483 15.2661 /L 164.7154 2029-Apr-14 05:43 01 25 22.83 +24 35 23.8 18. 11. 0.00124502123402 6.0119949 15.2528 /L 164.7286 2029-Apr-14 05:44 01 25 16.61 +24 34 31.2 18. 11. 0.00124743248011 6.0120399 15.2396 /L 164.7418 2029-Apr-14 05:45 01 25 10.42 +24 33 38.7 18. 11. 0.00124984374386 6.0120835 15.2265 /L 164.7549 2029-Apr-14 05:46 01 25 04.25 +24 32 46.4 18. 11. 0.00125225502464 6.0121255 15.2135 /L 164.7679 2029-Apr-14 05:47 01 24 58.10 +24 31 54.3 18. 11. 0.00125466632186 6.0121660 15.2006 /L 164.7808 2029-Apr-14 05:48 01 24 51.98 +24 31 02.4 18. 11. 0.00125707763490 6.0122050 15.1877 /L 164.7936 2029-Apr-14 05:49 01 24 45.89 +24 30 10.7 18. 11. 0.00125948896318 6.0122425 15.1750 /L 164.8063 2029-Apr-14 05:50 01 24 39.82 +24 29 19.2 18. 11. 0.00126190030611 6.0122786 15.1623 /L 164.8190 2029-Apr-14 05:51 01 24 33.77 +24 28 27.8 18. 11. 0.00126431166311 6.0123133 15.1497 /L 164.8315 2029-Apr-14 05:52 01 24 27.75 +24 27 36.6 18. 11. 0.00126672303361 6.0123465 15.1372 /L 164.8440 2029-Apr-14 05:53 01 24 21.75 +24 26 45.6 18. 12. 0.00126913441705 6.0123783 15.1248 /L 164.8564 2029-Apr-14 05:54 01 24 15.78 +24 25 54.8 18. 12. 0.00127154581286 6.0124088 15.1125 /L 164.8687 2029-Apr-14 05:55 01 24 09.83 +24 25 04.2 18. 12. 0.00127395722048 6.0124378 15.1003 /L 164.8809 2029-Apr-14 05:56 01 24 03.91 +24 24 13.7 18. 12. 0.00127636863937 6.0124655 15.0881 /L 164.8930 2029-Apr-14 05:57 01 23 58.00 +24 23 23.4 18. 12. 0.00127878006898 6.0124919 15.0761 /L 164.9051 2029-Apr-14 05:58 01 23 52.13 +24 22 33.3 18. 12. 0.00128119150879 6.0125169 15.0641 /L 164.9170 2029-Apr-14 05:59 01 23 46.27 +24 21 43.3 18. 12. 0.00128360295826 6.0125406 15.0522 /L 164.9289 2029-Apr-14 06:00 01 23 40.44 +24 20 53.6 18. 12. 0.00128601441687 6.0125630 15.0404 /L 164.9407 $$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 by introduction of integer leap-seconds for 1972 and later. Conversion from the internal TDB timescale to the non-uniform 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 on Earth, regardless of where the observer is located in the solar system. For example, if an observation from the surface of another body has an output time-tag of 12:31:00 UT, it refers to a time-scale conversion from TDB to UT valid at the center of the Earth, not the actual observer location elsewhere in the solar system, where clock rates may differ slightly due to the local spacetime metric and there is no precisely defined or adopted "UT" analog. Any 'b' symbol in the 1st-column denotes a B.C. date. First-column blank (" ") denotes an A.D. date. Calendar dates prior to 1582-Oct-15 are in the Julian calendar system. Later calendar dates are in the Gregorian system. NOTE: "n.a." in output means quantity "not available" at the print-time. R.A._(ICRF/J2000.0)_DEC = Astrometric right ascension and declination of the TARGET CENTER with respect to the observing site in the coordinates of the ICRF/J2000 inertial reference frame. Compensated for down-leg light-time. Units: RA in hours-minutes-seconds of time (HH MM SS.ff), DEC in angular degrees-minutes-seconds (DD MM SS.f) APmag S-brt = Asteroid's approximate apparent visual magnitude & surface brightness: APmag = H + 5*log10(delta) + 5*log10(r) - 2.5*log10((1-G)*phi1 + G*phi2) For solar phase angles > 90 deg, the error could exceed 1 magnitude. For phase angles > 120 degrees, output values are rounded to the nearest integer to indicate the errors could be large and unknown. Units: NONE & VISUAL MAGNITUDES PER SQUARE ARCSECOND delta deldot = Range ("delta") and range-rate ("delta-dot") of target center with respect to the observer at the instant light seen by the observer at print-time would have left the target center (print-time minus down-leg light-time); the distance traveled by a light ray emanating from the center of the target and recorded by the observer at print-time. "deldot" is a projection of the velocity vector along this ray, the light-time-corrected line-of-sight from the coordinate center, and indicates relative motion. A positive "deldot" means the target center is moving away from the observer (coordinate center). A negative "deldot" means the target center is moving toward the observer. Units: AU and KM/S S-O-T /r = Sun-Observer-Target angle; target's apparent SOLAR ELONGATION seen from the observer location at print-time. Angular units: DEGREES The '/r' column indicates the target's apparent position relative to the Sun in the observer's sky, as described below: For an observing location on the surface of a rotating body (considering its rotational sense): /T indicates target TRAILS Sun (evening sky; rises and sets AFTER Sun) /L indicates target LEADS Sun (morning sky; rises and sets BEFORE Sun) For an observing point NOT on a rotating body (such as a spacecraft), the "leading" and "trailing" condition is defined by the observer's heliocentric orbital motion: if continuing in the observer's current direction of heliocentric motion would encounter the target's 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 target's, the target TRAILS the Sun. NOTE: 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 are defined in the equator of a spherical coordinate system. S-T-O = "S-T-O" is the Sun->Target->Observer angle; the interior vertex angle at target center formed by a vector to the apparent center of the Sun at reflection time on the target and the apparent vector 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 Computations by ... Solar System Dynamics Group, Horizons On-Line Ephemeris System 4800 Oak Grove Drive, Jet Propulsion Laboratory Pasadena, CA 91109 USA Information: http://ssd.jpl.nasa.gov/ Connect : telnet://ssd.jpl.nasa.gov:6775 (via browser) telnet ssd.jpl.nasa.gov 6775 (via command-line) Author : Jon.D.Giorgini@jpl.nasa.gov **************************************************************************************************************