Occultation event with (11509) Thersilochos, event index number 4642
Regions able to see the event: SAmericaS
Geocentric closest approach at 2026/11/11 06:27:40 UTC
J2000 position of star is 06:11:44.1 +06:32:11
Equinox of date position of star is 06:13:10.8 +06:31:42
Star is 149 degrees from the moon. Moon is 4% illuminated.
Stellar brightness G=13.9, apparent brightess of occulting body is G=15.4
Use an exposure time of 0.25 seconds with the standard RECON-QHY system.
SNR of 9.4 per integration for unocculted signal
Expected flux drop is 80% with SNR of 7.5 for the occulted depth (per occulted point)
Apparent velocity is 12.4 km/sec on the sky relative to the star, or, 13.7 arcsec/hr.
Position angle of asteroid motion is 50.8 degrees
The recommended exposure time corresponds to 3.1 km per image.
The 1-sigma error in the time of the event is 1.1 seconds.
The 1-sigma cross-track error in the shadow position is 26.1 km.
The sky-plane scale is 3269.3 km/arcsec.
Diameter estimates:
55.0 km assuming a 5% albedo, maximum of 4.4 sec for a central chord
22.4 km assuming a 30% albedo, maximum of 1.8 sec for a central chord
Cross-track diameter of 50.0 km used for deployment plan.
Star training set for 11509_Thersilochos, (2026/11/11 06:28UT) Object RA Dec mag sep mel Betelgeuse 05:56:37.6 +07:24:35 0.4 4.20 153 Bellatrix 05:26:34.4 +06:22:18 1.6 11.58 156 PPM 150179 06:17:06.6 +06:03:19 5.8 1.09 148 PPM 150073 06:13:27.8 +06:46:22 7.2 0.25 149 PPM 150074 06:13:34.5 +06:18:25 9.8 0.24 149 PPM 150036 06:12:29.6 +06:23:05 10.5 0.22 149 11509_Thersilo 06:13:10.8 +06:31:42 15.4 149 Positions are for equinox of date
Star training set for 11509_Thersilochos, (2026/11/11 06:28UT) Object RA Dec mag sep mel Betelgeuse 05:55:10.3 +07:24:26 0.4 4.20 153 Bellatrix 05:25:07.8 +06:20:58 1.6 11.58 156 PPM 150179 06:15:40.2 +06:03:57 5.8 1.09 148 PPM 150073 06:12:00.9 +06:46:52 7.2 0.25 149 PPM 150074 06:12:07.9 +06:18:55 9.8 0.24 149 PPM 150036 06:11:03.0 +06:23:32 10.5 0.22 149 11509_Thersilo 06:11:44.1 +06:32:11 15.4 149 Positions are for J2000