Occultation event with (4902) Thessandrus, event index number 1055
Regions able to see the event: Australia
Geocentric closest approach at 2025/06/13 12:18:51 UTC
J2000 position of star is 09:25:14.2 +12:02:45
Equinox of date position of star is 09:26:36.9 +11:56:06
Star is 147 degrees from the moon. Moon is 95% illuminated.
Stellar brightness G=13.6, apparent brightess of occulting body is G=15.6
Use an exposure time of 0.20 seconds with the standard RECON-QHY system.
SNR of 9.8 per integration for unocculted signal
Expected flux drop is 85% with SNR of 8.4 for the occulted depth (per occulted point)
Apparent velocity is 28.9 km/sec on the sky relative to the star, or, 25.7 arcsec/hr.
Position angle of asteroid motion is 346.3 degrees
The recommended exposure time corresponds to 5.8 km per image.
The 1-sigma error in the time of the event is 1.6 seconds.
The 1-sigma cross-track error in the shadow position is 14.0 km.
The sky-plane scale is 4043.2 km/arcsec.
Diameter estimates:
64.6 km assuming a 5% albedo, aximum of 2.2 sec for a central chord
26.4 km assuming a 30% albedo, maximum of 0.9 sec for a central chord
Cross-track diameter of 64.6 km used for deployment plan.
Star training set for 4902_Thessandrus, (2025/06/13 12:19UT) Object RA Dec mag sep mel Regulus 10:09:43.5 +11:50:31 1.3 10.55 138 5Xi Leo 09:33:18.9 +11:11:09 5.0 1.80 145 PPM 126472 09:28:59.2 +12:17:16 7.9 0.68 147 PPM 126418 09:25:43.2 +12:24:34 9.5 0.52 148 PPM 126434 09:26:36.9 +12:04:28 11.0 0.14 147 4902_Thessandr 09:26:36.9 +11:56:06 15.6 147 Positions are for equinox of date
Star training set for 4902_Thessandrus, (2025/06/13 12:19UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 10.55 138 5Xi Leo 09:31:56.6 +11:17:57 5.0 1.80 145 PPM 126472 09:27:36.4 +12:23:59 7.9 0.68 147 PPM 126418 09:24:20.2 +12:31:11 9.5 0.52 148 PPM 126434 09:25:14.1 +12:11:07 11.0 0.14 147 4902_Thessandr 09:25:14.2 +12:02:45 15.6 147 Positions are for J2000