Occultation event with (21601) 98XO89, event index number 3989
Regions able to see the event: SAfrica
Geocentric closest approach at 2026/08/11 16:39:32 UTC
J2000 position of star is 13:33:07.6 -23:34:58
Equinox of date position of star is 13:34:35.6 -23:43:07
Star is 86 degrees from the moon. Moon is 2% illuminated.
Stellar brightness G=16.1, apparent brightess of occulting body is G=15.8
Use an exposure time of 0.65 seconds with the standard RECON-QHY system.
SNR of 3.1 per integration for unocculted signal
Expected flux drop is 43% with SNR of 1.3 for the occulted depth (per occulted point)
Apparent velocity is 23.7 km/sec on the sky relative to the star, or, 21.4 arcsec/hr.
Position angle of asteroid motion is 90.2 degrees
The recommended exposure time corresponds to 15.4 km per image.
The 1-sigma error in the time of the event is 0.3 seconds.
The 1-sigma cross-track error in the shadow position is 35.6 km.
The sky-plane scale is 3998.8 km/arcsec.
Diameter estimates:
60.0 km assuming a 5% albedo, maximum of 2.5 sec for a central chord
24.5 km assuming a 30% albedo, maximum of 1.0 sec for a central chord
Cross-track diameter of 54.9 km used for deployment plan.
Star training set for 21601_98XO89, (2026/08/11 16:40UT) Object RA Dec mag sep mel Spica 13:26:35.9 -11:17:58 1.0 12.56 79 PPM 261719 13:31:10.4 -23:25:05 5.9 0.84 85 PPM 261734 13:31:57.4 -23:47:10 8.3 0.61 85 PPM 261792 13:34:42.7 -23:49:16 9.6 0.11 86 21601_98XO89 13:34:35.6 -23:43:07 15.8 86 Positions are for equinox of date
Star training set for 21601_98XO89, (2026/08/11 16:40UT) Object RA Dec mag sep mel Spica 13:25:11.5 -11:09:41 1.0 12.56 79 PPM 261719 13:29:42.7 -23:16:52 5.9 0.84 85 PPM 261734 13:30:29.5 -23:38:58 8.3 0.61 85 PPM 261792 13:33:14.7 -23:41:07 9.6 0.11 86 21601_98XO89 13:33:07.6 -23:34:58 15.8 86 Positions are for J2000