Occultation event with (1868) Thersites, event index number 3854
Regions able to see the event: Australia
Geocentric closest approach at 2026/07/17 10:36:30 UTC
J2000 position of star is 11:01:18.5 -00:25:13
Equinox of date position of star is 11:02:40.0 -00:33:48
Star is 12 degrees from the moon. Moon is 12% illuminated.
Stellar brightness G=14.5, apparent brightess of occulting body is G=15.7
Use an exposure time of 0.50 seconds with the standard RECON-QHY system.
SNR of 9.6 per integration for unocculted signal
Expected flux drop is 75% with SNR of 7.2 for the occulted depth (per occulted point)
Apparent velocity is 29.8 km/sec on the sky relative to the star, or, 23.0 arcsec/hr.
Position angle of asteroid motion is 102.3 degrees
The recommended exposure time corresponds to 14.9 km per image.
The 1-sigma error in the time of the event is 0.4 seconds.
The 1-sigma cross-track error in the shadow position is 36.0 km.
The sky-plane scale is 4663.2 km/arcsec.
Diameter estimates:
76.9 km assuming a 5% albedo, maximum of 2.6 sec for a central chord
31.4 km assuming a 30% albedo, maximum of 1.1 sec for a central chord
Cross-track diameter of 68.2 km used for deployment plan.
Star training set for 1868_Thersites, (2026/07/17 10:37UT) Object RA Dec mag sep mel Regulus 10:09:47.0 +11:50:11 1.3 18.06 6 PPM 178367 11:04:36.0 -00:53:48 6.2 0.59 12 PPM 178362 11:03:54.8 -00:14:12 7.6 0.45 12 PPM 178355 11:01:25.2 -00:46:11 11.4 0.37 12 1868_Thersites 11:02:40.0 -00:33:48 15.7 12 Positions are for equinox of date
Star training set for 1868_Thersites, (2026/07/17 10:37UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 18.06 6 PPM 178367 11:03:14.5 -00:45:12 6.2 0.59 12 PPM 178362 11:02:33.2 -00:05:37 7.6 0.45 12 PPM 178355 11:00:03.7 -00:37:36 11.4 0.37 12 1868_Thersites 11:01:18.5 -00:25:13 15.7 12 Positions are for J2000