Occultation event with (21601) 98XO89, event index number 3664
Regions able to see the event: Australia,NZ
Geocentric closest approach at 2026/04/20 09:01:54 UTC
J2000 position of star is 13:30:24.5 -30:03:05
Equinox of date position of star is 13:31:53.2 -30:11:11
Star is 140 degrees from the moon. Moon is 12% illuminated.
Stellar brightness G=15.8, apparent brightess of occulting body is G=14.9
Use an exposure time of 0.80 seconds with the standard RECON-QHY system.
SNR of 4.4 per integration for unocculted signal
Expected flux drop is 31% with SNR of 1.4 for the occulted depth (per occulted point)
Apparent velocity is 17.1 km/sec on the sky relative to the star, or, 19.7 arcsec/hr.
Position angle of asteroid motion is 120.2 degrees
The recommended exposure time corresponds to 13.7 km per image.
The 1-sigma error in the time of the event is 1.4 seconds.
The 1-sigma cross-track error in the shadow position is 27.4 km.
The sky-plane scale is 3118.6 km/arcsec.
Diameter estimates:
60.0 km assuming a 5% albedo, maximum of 3.5 sec for a central chord
24.5 km assuming a 30% albedo, maximum of 1.4 sec for a central chord
Cross-track diameter of 54.9 km used for deployment plan.
Star training set for 21601_98XO89, (2026/04/20 09:02UT) Object RA Dec mag sep mel Spica 13:26:34.9 -11:17:52 1.0 18.93 133 Iot Cen 13:22:05.1 -36:51:01 2.8 6.97 139 PPM 261770 13:34:04.2 -28:49:39 5.7 1.44 141 PPM 261768 13:34:03.1 -29:41:59 6.9 0.68 141 PPM 291471 13:31:55.0 -30:11:23 9.7 0.01 140 21601_98XO89 13:31:53.2 -30:11:11 14.9 141 Positions are for equinox of date
Star training set for 21601_98XO89, (2026/04/20 09:02UT) Object RA Dec mag sep mel Spica 13:25:11.5 -11:09:41 1.0 18.93 133 Iot Cen 13:20:35.1 -36:42:46 2.8 6.97 139 PPM 261770 13:32:35.7 -28:41:35 5.7 1.44 141 PPM 261768 13:32:34.3 -29:33:55 6.9 0.68 141 PPM 291471 13:30:26.2 -30:03:17 9.7 0.01 140 21601_98XO89 13:30:24.5 -30:03:05 14.9 140 Positions are for J2000