Occultation event with (11509) Thersilochos, event index number 3512
Regions able to see the event: SAmericaN
Geocentric closest approach at 2026/03/26 22:11:20 UTC
J2000 position of star is 03:45:56.2 +10:50:50
Equinox of date position of star is 03:47:22.5 +10:55:39
Star is 55 degrees from the moon. Moon is 63% illuminated.
Stellar brightness G=9.6, apparent brightess of occulting body is G=15.8
Use an exposure time of 0.12 seconds with the standard RECON-QHY system.
SNR of 66.5 per integration for unocculted signal
Expected flux drop is 100% with SNR of 66.3 for the occulted depth (per occulted point)
Apparent velocity is 31.5 km/sec on the sky relative to the star, or, 28.2 arcsec/hr.
Position angle of asteroid motion is 77.9 degrees
The recommended exposure time corresponds to 3.8 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 29.0 km.
The sky-plane scale is 4021.7 km/arcsec.
Diameter estimates:
55.0 km assuming a 5% albedo, maximum of 1.7 sec for a central chord
22.4 km assuming a 30% albedo, maximum of 0.7 sec for a central chord
Cross-track diameter of 50.0 km used for deployment plan.
Star training set for 11509_Thersilochos, (2026/03/26 22:11UT) Object RA Dec mag sep mel Aldebaran 04:37:25.7 +16:33:36 0.8 13.39 42 Menkar 03:03:39.2 +04:11:28 2.5 12.75 68 30 Tau 03:49:42.8 +11:13:19 4.8 0.64 55 PPM 119341 03:47:32.4 +10:37:44 8.5 0.30 55 PPM 119333 03:46:50.7 +10:45:13 10.0 0.22 56 11509_Thersilo 03:47:22.5 +10:55:39 15.8 55 Positions are for equinox of date
Star training set for 11509_Thersilochos, (2026/03/26 22:11UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 13.39 42 Menkar 03:02:16.8 +04:05:21 2.5 12.75 68 30 Tau 03:48:16.3 +11:08:35 4.8 0.64 55 PPM 119341 03:46:06.3 +10:32:56 8.5 0.30 55 PPM 119333 03:45:24.5 +10:40:23 10.0 0.22 56 11509_Thersilo 03:45:56.2 +10:50:50 15.8 55 Positions are for J2000