Occultation event with (4834) Thoas, event index number 3251
Regions able to see the event: Senegal
Geocentric closest approach at 2026/02/15 23:11:40 UTC
J2000 position of star is 13:02:45.1 +29:46:06
Equinox of date position of star is 13:04:00.0 +29:37:42
Star is 122 degrees from the moon. Moon is 3% illuminated.
Stellar brightness G=13.1, apparent brightess of occulting body is G=14.4
Use an exposure time of 0.12 seconds with the standard RECON-QHY system.
SNR of 9.7 per integration for unocculted signal
Expected flux drop is 77% with SNR of 7.5 for the occulted depth (per occulted point)
Apparent velocity is 14.5 km/sec on the sky relative to the star, or, 15.8 arcsec/hr.
Position angle of asteroid motion is 149.0 degrees
The recommended exposure time corresponds to 1.7 km per image.
The 1-sigma error in the time of the event is 2.6 seconds.
The 1-sigma cross-track error in the shadow position is 2.9 km.
The sky-plane scale is 3298.2 km/arcsec.
Diameter estimates:
89.1 km assuming a 5% albedo, maximum of 6.2 sec for a central chord
36.4 km assuming a 30% albedo, maximum of 2.5 sec for a central chord
Cross-track diameter of 72.3 km used for deployment plan.
Star training set for 4834_Thoas, (2026/02/15 23:12UT) Object RA Dec mag sep mel Arcturus 14:16:51.3 +19:02:52 0.0 19.64 104 Vindemiatrix 13:03:28.7 +10:49:09 2.8 18.81 119 PPM 102376 13:07:24.8 +28:53:23 6.5 1.05 122 PPM 076885 13:03:35.5 +30:13:04 8.4 0.60 123 PPM 102325 13:03:08.0 +29:26:33 10.4 0.26 123 4834_Thoas 13:04:00.0 +29:37:42 14.4 122 Positions are for equinox of date
Star training set for 4834_Thoas, (2026/02/15 23:12UT) Object RA Dec mag sep mel Arcturus 14:15:37.7 +19:10:06 0.0 19.64 104 Vindemiatrix 13:02:10.1 +10:57:33 2.8 18.81 119 PPM 102376 13:06:10.0 +29:01:45 6.5 1.05 122 PPM 076885 13:02:20.7 +30:21:28 8.4 0.60 123 PPM 102325 13:01:53.0 +29:34:57 10.4 0.26 123 4834_Thoas 13:02:45.1 +29:46:06 14.4 122 Positions are for J2000