Occultation event with (20729) 99XS143, event index number 3673
Regions able to see the event: SAmericaS
Geocentric closest approach at 2026/04/22 05:33:14 UTC
J2000 position of star is 10:54:52.6 -15:20:13
Equinox of date position of star is 10:56:10.8 -15:28:40
Star is 76 degrees from the moon. Moon is 29% illuminated.
Stellar brightness G=13.1, apparent brightess of occulting body is G=15.9
Use an exposure time of 0.12 seconds with the standard RECON-QHY system.
SNR of 10.1 per integration for unocculted signal
Expected flux drop is 93% with SNR of 9.4 for the occulted depth (per occulted point)
Apparent velocity is 11.4 km/sec on the sky relative to the star, or, 12.0 arcsec/hr.
Position angle of asteroid motion is 130.6 degrees
The recommended exposure time corresponds to 1.4 km per image.
The 1-sigma error in the time of the event is 3.4 seconds.
The 1-sigma cross-track error in the shadow position is 5.8 km.
The sky-plane scale is 3415.2 km/arcsec.
Diameter estimates:
48.3 km assuming a 5% albedo, maximum of 4.3 sec for a central chord
19.7 km assuming a 30% albedo, maximum of 1.7 sec for a central chord
Cross-track diameter of 51.0 km used for deployment plan.
Star training set for 20729_99XS143, (2026/04/22 05:33UT) Object RA Dec mag sep mel Regulus 10:09:46.2 +11:50:15 1.3 29.63 52 4Gam Crv 12:17:09.8 -17:41:16 2.6 19.52 94 PPM 223610 10:54:51.1 -15:35:12 6.3 0.34 76 PPM 223643 10:56:12.6 -15:35:32 8.8 0.11 76 20729_99XS143 10:56:10.8 -15:28:40 15.9 77 Positions are for equinox of date
Star training set for 20729_99XS143, (2026/04/22 05:33UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 29.63 52 4Gam Crv 12:15:48.1 -17:32:30 2.6 19.52 94 PPM 223610 10:53:33.0 -15:26:46 6.3 0.34 76 PPM 223643 10:54:54.4 -15:27:06 8.8 0.11 76 20729_99XS143 10:54:52.6 -15:20:13 15.9 76 Positions are for J2000