Occultation event with (4902) Thessandrus, event index number 1133
Regions able to see the event: SAmericaN
Geocentric closest approach at 2025/07/12 22:36:02 UTC
J2000 position of star is 09:47:35.0 +10:41:47
Equinox of date position of star is 09:48:57.0 +10:34:38
Star is 169 degrees from the moon. Moon is 95% illuminated.
Stellar brightness G=16.0, apparent brightess of occulting body is G=15.6
Use an exposure time of 0.55 seconds with the standard RECON-QHY system.
SNR of 3.0 per integration for unocculted signal
Expected flux drop is 40% with SNR of 1.2 for the occulted depth (per occulted point)
Apparent velocity is 37.2 km/sec on the sky relative to the star, or, 31.3 arcsec/hr.
Position angle of asteroid motion is 343.3 degrees
The recommended exposure time corresponds to 20.5 km per image.
The 1-sigma error in the time of the event is 1.3 seconds.
The 1-sigma cross-track error in the shadow position is 17.3 km.
The sky-plane scale is 4285.4 km/arcsec.
Diameter estimates:
64.6 km assuming a 5% albedo, aximum of 1.7 sec for a central chord
26.4 km assuming a 30% albedo, maximum of 0.7 sec for a central chord
Cross-track diameter of 64.6 km used for deployment plan.
Star training set for 4902_Thessandrus, (2025/07/12 22:36UT) Object RA Dec mag sep mel Regulus 10:09:43.7 +11:50:29 1.3 5.25 166 PPM 126849 09:52:11.5 +11:43:18 6.5 1.39 169 PPM 126799 09:49:03.2 +10:15:56 7.7 0.31 169 PPM 126793 09:48:51.3 +10:43:30 8.7 0.15 169 4902_Thessandr 09:48:57.0 +10:34:38 15.6 169 Positions are for equinox of date
Star training set for 4902_Thessandrus, (2025/07/12 22:36UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 5.25 166 PPM 126849 09:50:49.2 +11:50:32 6.5 1.39 169 PPM 126799 09:47:41.3 +10:23:06 7.7 0.31 169 PPM 126793 09:47:29.3 +10:50:39 8.7 0.15 169 4902_Thessandr 09:47:35.0 +10:41:47 15.6 169 Positions are for J2000