Occultation event with (4902) Thessandrus, event index number 3668
Regions able to see the event: Australia
Geocentric closest approach at 2026/04/21 11:56:24 UTC
J2000 position of star is 11:17:40.9 +05:38:41
Equinox of date position of star is 11:19:02.4 +05:30:03
Star is 81 degrees from the moon. Moon is 22% illuminated.
Stellar brightness G=15.7, apparent brightess of occulting body is G=15.0
Use an exposure time of 1.35 seconds with the standard RECON-QHY system.
SNR of 6.4 per integration for unocculted signal
Expected flux drop is 34% with SNR of 2.2 for the occulted depth (per occulted point)
Apparent velocity is 9.3 km/sec on the sky relative to the star, or, 10.5 arcsec/hr.
Position angle of asteroid motion is 123.7 degrees
The recommended exposure time corresponds to 12.6 km per image.
The 1-sigma error in the time of the event is 3.0 seconds.
The 1-sigma cross-track error in the shadow position is 25.4 km.
The sky-plane scale is 3205.5 km/arcsec.
Diameter estimates:
64.9 km assuming a 5% albedo, maximum of 7.0 sec for a central chord
26.5 km assuming a 30% albedo, maximum of 2.8 sec for a central chord
Cross-track diameter of 51.3 km used for deployment plan.
Star training set for 4902_Thessandrus, (2026/04/21 11:56UT) Object RA Dec mag sep mel Regulus 10:09:46.2 +11:50:15 1.3 18.24 63 Denebola 11:50:24.0 +14:25:30 2.1 11.80 84 77Sig Leo 11:22:29.5 +05:53:05 4.0 0.94 82 PPM 157764 11:22:20.3 +04:44:09 7.8 1.12 82 PPM 157706 11:19:14.0 +05:29:44 9.7 0.05 81 4902_Thessandr 11:19:02.4 +05:30:03 15.0 81 Positions are for equinox of date
Star training set for 4902_Thessandrus, (2026/04/21 11:56UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 18.24 63 Denebola 11:49:02.7 +14:34:16 2.1 11.80 84 77Sig Leo 11:21:08.0 +06:01:45 4.0 0.94 82 PPM 157764 11:20:59.0 +04:52:49 7.8 1.12 82 PPM 157706 11:17:52.5 +05:38:22 9.7 0.05 81 4902_Thessandr 11:17:40.9 +05:38:41 15.0 81 Positions are for J2000