Occultation event with (4035) Thestor, event index number 958
Regions able to see the event: SAmericaN
Geocentric closest approach at 2025/05/08 21:24:11 UTC
J2000 position of star is 08:40:21.8 +05:51:29
Equinox of date position of star is 08:41:42.4 +05:46:01
Star is 57 degrees from the moon. Moon is 88% illuminated.
Stellar brightness G=13.1, apparent brightess of occulting body is G=15.2
Use an exposure time of 0.12 seconds with the standard RECON-QHY system.
SNR of 9.9 per integration for unocculted signal
Expected flux drop is 87% with SNR of 8.6 for the occulted depth (per occulted point)
Apparent velocity is 17.3 km/sec on the sky relative to the star, or, 16.6 arcsec/hr.
Position angle of asteroid motion is 359.5 degrees
The recommended exposure time corresponds to 2.1 km per image.
The 1-sigma error in the time of the event is 2.3 seconds.
The 1-sigma cross-track error in the shadow position is 12.7 km.
The sky-plane scale is 3757.0 km/arcsec.
Diameter estimates:
73.8 km assuming a 5% albedo, aximum of 4.3 sec for a central chord
30.1 km assuming a 30% albedo, maximum of 1.7 sec for a central chord
Cross-track diameter of 73.8 km used for deployment plan.
Star training set for 4035_Thestor, (2025/05/08 21:24UT) Object RA Dec mag sep mel Regulus 10:09:43.2 +11:50:32 1.3 22.56 37 Alphard 09:28:50.0 -08:46:11 2.0 18.69 44 4Del Hya 08:38:59.8 +05:36:50 4.2 0.69 57 PPM 154823 08:41:34.2 +06:28:29 7.7 0.71 57 PPM 154816 08:41:05.6 +05:40:39 8.7 0.18 57 4035_Thestor 08:41:42.4 +05:46:01 15.2 56 Positions are for equinox of date
Star training set for 4035_Thestor, (2025/05/08 21:24UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 22.56 37 Alphard 09:27:35.2 -08:39:30 2.0 18.69 44 4Del Hya 08:37:39.3 +05:42:13 4.2 0.69 57 PPM 154823 08:40:13.3 +06:33:58 7.7 0.71 57 PPM 154816 08:39:45.0 +05:46:06 8.7 0.18 57 4035_Thestor 08:40:21.8 +05:51:29 15.2 57 Positions are for J2000