Occultation event with (20729) 99XS143, event index number 1404
Regions able to see the event: Australia
Geocentric closest approach at 2025/10/23 19:05:53 UTC
J2000 position of star is 11:09:26.1 -07:52:32
Equinox of date position of star is 11:10:44.5 -08:00:57
Star is 64 degrees from the moon. Moon is 5% illuminated.
Stellar brightness G=14.4, apparent brightess of occulting body is G=16.4
Use an exposure time of 0.35 seconds with the standard RECON-QHY system.
SNR of 8.4 per integration for unocculted signal
Expected flux drop is 86% with SNR of 7.2 for the occulted depth (per occulted point)
Apparent velocity is 35.8 km/sec on the sky relative to the star, or, 29.0 arcsec/hr.
Position angle of asteroid motion is 125.5 degrees
The recommended exposure time corresponds to 12.5 km per image.
The 1-sigma error in the time of the event is 1.1 seconds.
The 1-sigma cross-track error in the shadow position is 10.3 km.
The sky-plane scale is 4442.7 km/arcsec.
Diameter estimates:
48.3 km assuming a 5% albedo, aximum of 1.3 sec for a central chord
19.7 km assuming a 30% albedo, maximum of 0.6 sec for a central chord
Cross-track diameter of 51.0 km used for deployment plan.
Star training set for 20729_99XS143, (2025/10/23 19:06UT) Object RA Dec mag sep mel Regulus 10:09:44.6 +11:50:24 1.3 24.98 86 4Gam Crv 12:17:08.2 -17:41:06 2.6 18.83 45 PPM 194312 11:18:16.7 -07:16:33 6.1 2.01 62 PPM 194178 11:11:31.4 -07:31:52 7.0 0.52 64 PPM 194148 11:09:23.6 -08:00:31 9.5 0.33 64 20729_99XS143 11:10:44.5 -08:00:57 16.4 63 Positions are for equinox of date
Star training set for 20729_99XS143, (2025/10/23 19:06UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 24.98 86 4Gam Crv 12:15:48.1 -17:32:30 2.6 18.83 45 PPM 194312 11:16:58.2 -07:08:05 6.1 2.01 62 PPM 194178 11:10:13.0 -07:23:27 7.0 0.52 64 PPM 194148 11:08:05.3 -07:52:07 9.5 0.33 64 20729_99XS143 11:09:26.1 -07:52:32 16.4 64 Positions are for J2000