Occultation event with (11509) Thersilochos, event index number 4163
Regions able to see the event: Senegal
Geocentric closest approach at 2026/09/03 06:02:30 UTC
J2000 position of star is 06:01:22.1 +10:47:30
Equinox of date position of star is 06:02:50.9 +10:47:26
Star is 38 degrees from the moon. Moon is 62% illuminated.
Stellar brightness G=13.7, apparent brightess of occulting body is G=15.9
Use an exposure time of 0.20 seconds with the standard RECON-QHY system.
SNR of 9.3 per integration for unocculted signal
Expected flux drop is 88% with SNR of 8.2 for the occulted depth (per occulted point)
Apparent velocity is 23.5 km/sec on the sky relative to the star, or, 21.6 arcsec/hr.
Position angle of asteroid motion is 111.4 degrees
The recommended exposure time corresponds to 4.7 km per image.
The 1-sigma error in the time of the event is 0.7 seconds.
The 1-sigma cross-track error in the shadow position is 24.4 km.
The sky-plane scale is 3920.9 km/arcsec.
Diameter estimates:
55.0 km assuming a 5% albedo, maximum of 2.3 sec for a central chord
22.4 km assuming a 30% albedo, maximum of 1.0 sec for a central chord
Cross-track diameter of 50.0 km used for deployment plan.
Star training set for 11509_Thersilochos, (2026/09/03 06:02UT) Object RA Dec mag sep mel Betelgeuse 05:56:37.0 +07:24:35 0.4 3.71 38 Bellatrix 05:26:33.8 +06:22:18 1.6 10.00 33 PPM 121823 06:04:54.2 +11:40:41 6.0 1.02 38 PPM 121844 06:05:37.3 +11:00:44 8.2 0.72 39 PPM 121723 06:01:25.5 +10:51:03 9.6 0.35 38 PPM 121796 06:03:46.4 +10:40:09 11.1 0.26 38 11509_Thersilo 06:02:50.9 +10:47:26 15.9 38 Positions are for equinox of date
Star training set for 11509_Thersilochos, (2026/09/03 06:02UT) Object RA Dec mag sep mel Betelgeuse 05:55:10.3 +07:24:26 0.4 3.71 38 Bellatrix 05:25:07.8 +06:20:58 1.6 10.00 33 PPM 121823 06:03:24.8 +11:40:51 6.0 1.02 38 PPM 121844 06:04:08.3 +11:00:55 8.2 0.72 39 PPM 121723 05:59:56.7 +10:51:05 9.6 0.35 38 PPM 121796 06:02:17.7 +10:40:16 11.1 0.26 38 11509_Thersilo 06:01:22.1 +10:47:30 15.9 38 Positions are for J2000