Occultation event with (20729) 99XS143, event index number 955
Regions able to see the event: SAmericaS
Geocentric closest approach at 2025/05/08 00:35:36 UTC
J2000 position of star is 09:20:26.7 +05:02:07
Equinox of date position of star is 09:21:46.5 +04:55:36
Star is 37 degrees from the moon. Moon is 82% illuminated.
Stellar brightness G=14.7, apparent brightess of occulting body is G=16.2
Use an exposure time of 0.60 seconds with the standard RECON-QHY system.
SNR of 9.7 per integration for unocculted signal
Expected flux drop is 79% with SNR of 7.7 for the occulted depth (per occulted point)
Apparent velocity is 9.5 km/sec on the sky relative to the star, or, 9.1 arcsec/hr.
Position angle of asteroid motion is 334.2 degrees
The recommended exposure time corresponds to 5.7 km per image.
The 1-sigma error in the time of the event is 3.8 seconds.
The 1-sigma cross-track error in the shadow position is 32.5 km.
The sky-plane scale is 3754.6 km/arcsec.
Diameter estimates:
48.3 km assuming a 5% albedo, aximum of 5.1 sec for a central chord
19.7 km assuming a 30% albedo, maximum of 2.1 sec for a central chord
Cross-track diameter of 48.3 km used for deployment plan.
Star training set for 20729_99XS143, (2025/05/08 00:36UT) Object RA Dec mag sep mel Regulus 10:09:43.2 +11:50:32 1.3 13.72 27 PPM 155539 09:13:32.3 +03:45:42 6.0 2.36 39 PPM 155692 09:21:11.0 +05:06:27 6.9 0.23 37 PPM 155696 09:21:16.5 +05:01:21 9.7 0.16 37 20729_99XS143 09:21:46.5 +04:55:36 16.2 37 Positions are for equinox of date
Star training set for 20729_99XS143, (2025/05/08 00:36UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 13.72 27 PPM 155539 09:12:12.8 +03:52:01 6.0 2.36 39 PPM 155692 09:19:51.1 +05:12:57 6.9 0.23 37 PPM 155696 09:19:56.6 +05:07:51 9.7 0.16 37 20729_99XS143 09:20:26.7 +05:02:07 16.2 37 Positions are for J2000