Occultation event with (11509) Thersilochos, event index number 5200
Regions able to see the event: Europe,SMexico
Geocentric closest approach at 2026/12/13 03:02:10 UTC
J2000 position of star is 05:57:54.0 +05:07:16
Equinox of date position of star is 05:59:20.1 +05:07:20
Star is 140 degrees from the moon. Moon is 14% illuminated.
Stellar brightness G=14.8, apparent brightess of occulting body is G=15.1
Use an exposure time of 0.70 seconds with the standard RECON-QHY system.
SNR of 9.2 per integration for unocculted signal
Expected flux drop is 57% with SNR of 5.3 for the occulted depth (per occulted point)
Apparent velocity is 17.8 km/sec on the sky relative to the star, or, 20.4 arcsec/hr.
Position angle of asteroid motion is 78.2 degrees
The recommended exposure time corresponds to 12.5 km per image.
The 1-sigma error in the time of the event is 0.1 seconds.
The 1-sigma cross-track error in the shadow position is 29.2 km.
The sky-plane scale is 3142.1 km/arcsec.
Diameter estimates:
55.0 km assuming a 5% albedo, maximum of 3.1 sec for a central chord
22.4 km assuming a 30% albedo, maximum of 1.3 sec for a central chord
Cross-track diameter of 50.0 km used for deployment plan.
Star training set for 11509_Thersilochos, (2026/12/13 03:02UT) Object RA Dec mag sep mel Betelgeuse 05:56:37.9 +07:24:35 0.4 2.38 140 Bellatrix 05:26:34.7 +06:22:19 1.6 8.24 133 PPM 149639 05:56:22.0 +05:51:49 6.4 1.05 139 PPM 149685 05:58:53.7 +05:00:10 7.8 0.16 139 11509_Thersilo 05:59:20.1 +05:07:20 15.1 140 Positions are for equinox of date
Star training set for 11509_Thersilochos, (2026/12/13 03:02UT) Object RA Dec mag sep mel Betelgeuse 05:55:10.3 +07:24:26 0.4 2.38 140 Bellatrix 05:25:07.8 +06:20:58 1.6 8.24 133 PPM 149639 05:54:55.4 +05:51:39 6.4 1.05 139 PPM 149685 05:57:27.6 +05:00:05 7.8 0.16 139 11509_Thersilo 05:57:54.0 +05:07:16 15.1 139 Positions are for J2000