Occultation event with (1868) Thersites, event index number 3670
Regions able to see the event: Europe
Geocentric closest approach at 2026/04/21 18:27:49 UTC
J2000 position of star is 10:37:04.1 -01:21:54
Equinox of date position of star is 10:38:24.7 -01:30:08
Star is 72 degrees from the moon. Moon is 25% illuminated.
Stellar brightness G=16.3, apparent brightess of occulting body is G=15.2
Use an exposure time of 1.65 seconds with the standard RECON-QHY system.
SNR of 4.6 per integration for unocculted signal
Expected flux drop is 27% with SNR of 1.2 for the occulted depth (per occulted point)
Apparent velocity is 10.3 km/sec on the sky relative to the star, or, 9.9 arcsec/hr.
Position angle of asteroid motion is 150.2 degrees
The recommended exposure time corresponds to 17.0 km per image.
The 1-sigma error in the time of the event is 3.5 seconds.
The 1-sigma cross-track error in the shadow position is 14.0 km.
The sky-plane scale is 3737.3 km/arcsec.
Diameter estimates:
76.9 km assuming a 5% albedo, maximum of 7.5 sec for a central chord
31.4 km assuming a 30% albedo, maximum of 3.0 sec for a central chord
Cross-track diameter of 68.2 km used for deployment plan.
Star training set for 1868_Thersites, (2026/04/21 18:28UT) Object RA Dec mag sep mel Regulus 10:09:46.2 +11:50:15 1.3 15.12 59 33 Sex 10:42:44.5 -01:52:50 6.3 1.15 73 PPM 178242 10:39:31.5 -02:06:46 8.5 0.67 72 PPM 178224 10:36:29.7 -01:40:05 11.3 0.51 71 1868_Thersites 10:38:24.7 -01:30:08 15.2 72 Positions are for equinox of date
Star training set for 1868_Thersites, (2026/04/21 18:28UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 15.12 59 33 Sex 10:41:24.0 -01:44:33 6.3 1.15 73 PPM 178242 10:38:11.1 -01:58:31 8.5 0.67 72 PPM 178224 10:35:09.1 -01:31:53 11.3 0.51 71 1868_Thersites 10:37:04.1 -01:21:54 15.2 72 Positions are for J2000