Occultation event with (4035) Thestor, event index number 3809
Regions able to see the event: SAmericaN
Geocentric closest approach at 2026/06/27 23:20:43 UTC
J2000 position of star is 10:55:48.1 -03:41:16
Equinox of date position of star is 10:57:08.9 -03:49:47
Star is 87 degrees from the moon. Moon is 96% illuminated.
Stellar brightness G=14.0, apparent brightess of occulting body is G=15.4
Use an exposure time of 0.30 seconds with the standard RECON-QHY system.
SNR of 9.9 per integration for unocculted signal
Expected flux drop is 78% with SNR of 7.7 for the occulted depth (per occulted point)
Apparent velocity is 23.1 km/sec on the sky relative to the star, or, 20.5 arcsec/hr.
Position angle of asteroid motion is 98.4 degrees
The recommended exposure time corresponds to 6.9 km per image.
The 1-sigma error in the time of the event is 0.8 seconds.
The 1-sigma cross-track error in the shadow position is 37.6 km.
The sky-plane scale is 4039.3 km/arcsec.
Diameter estimates:
74.5 km assuming a 5% albedo, maximum of 3.2 sec for a central chord
30.4 km assuming a 30% albedo, maximum of 1.3 sec for a central chord
Cross-track diameter of 68.7 km used for deployment plan.
Star training set for 4035_Thestor, (2026/06/27 23:21UT) Object RA Dec mag sep mel Regulus 10:09:46.8 +11:50:12 1.3 19.60 104 PPM 193861 10:52:26.2 -03:14:01 5.8 1.32 88 PPM 193915 10:55:21.8 -04:11:00 8.4 0.57 87 PPM 193941 10:57:08.2 -03:53:31 9.7 0.06 87 4035_Thestor 10:57:08.9 -03:49:47 15.4 86 Positions are for equinox of date
Star training set for 4035_Thestor, (2026/06/27 23:21UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 19.60 104 PPM 193861 10:51:05.3 -03:05:34 5.8 1.32 88 PPM 193915 10:54:01.1 -04:02:31 8.4 0.57 87 PPM 193941 10:55:47.4 -03:45:00 9.7 0.06 87 4035_Thestor 10:55:48.1 -03:41:16 15.4 87 Positions are for J2000