Occultation event with (20729) 99XS143, event index number 3338
Regions able to see the event: SAmericaN
Geocentric closest approach at 2026/03/03 10:29:39 UTC
J2000 position of star is 11:17:33.6 -17:22:58
Equinox of date position of star is 11:18:52.1 -17:31:34
Star is 25 degrees from the moon. Moon is 100% illuminated.
Stellar brightness G=16.6, apparent brightess of occulting body is G=15.6
Use an exposure time of 1.25 seconds with the standard RECON-QHY system.
SNR of 3.0 per integration for unocculted signal
Expected flux drop is 29% with SNR of 0.9 for the occulted depth (per occulted point)
Apparent velocity is 17.8 km/sec on the sky relative to the star, or, 19.5 arcsec/hr.
Position angle of asteroid motion is 95.9 degrees
The recommended exposure time corresponds to 22.2 km per image.
The 1-sigma error in the time of the event is 1.6 seconds.
The 1-sigma cross-track error in the shadow position is 28.1 km.
The sky-plane scale is 3291.8 km/arcsec.
Diameter estimates:
48.3 km assuming a 5% albedo, maximum of 2.7 sec for a central chord
19.7 km assuming a 30% albedo, maximum of 1.1 sec for a central chord
Cross-track diameter of 51.0 km used for deployment plan.
Star training set for 20729_99XS143, (2026/03/03 10:30UT) Object RA Dec mag sep mel Spica 13:26:34.5 -11:17:49 1.0 31.50 42 4Gam Crv 12:17:09.4 -17:41:14 2.6 13.89 32 Psi Crt 11:13:48.4 -18:38:34 6.4 1.64 26 PPM 224123 11:15:28.9 -17:01:43 7.2 0.95 24 PPM 224190 11:18:26.6 -17:29:56 9.6 0.10 25 20729_99XS143 11:18:52.1 -17:31:34 15.6 25 Positions are for equinox of date
Star training set for 20729_99XS143, (2026/03/03 10:30UT) Object RA Dec mag sep mel Spica 13:25:11.5 -11:09:41 1.0 31.50 42 4Gam Crv 12:15:48.1 -17:32:30 2.6 13.89 32 Psi Crt 11:12:30.3 -18:30:00 6.4 1.64 26 PPM 224123 11:14:10.5 -16:53:09 7.2 0.95 24 PPM 224190 11:17:08.2 -17:21:21 9.6 0.10 25 20729_99XS143 11:17:33.6 -17:22:58 15.6 25 Positions are for J2000