Occultation event with (11509) Thersilochos, event index number 4479
Regions able to see the event: SAmericaN
Geocentric closest approach at 2026/10/25 02:45:06 UTC
J2000 position of star is 06:14:46.2 +07:35:33
Equinox of date position of star is 06:16:13.5 +07:34:56
Star is 78 degrees from the moon. Moon is 98% illuminated.
Stellar brightness G=13.2, apparent brightess of occulting body is G=15.6
Use an exposure time of 0.13 seconds with the standard RECON-QHY system.
SNR of 9.8 per integration for unocculted signal
Expected flux drop is 90% with SNR of 8.8 for the occulted depth (per occulted point)
Apparent velocity is 9.4 km/sec on the sky relative to the star, or, 10.0 arcsec/hr.
Position angle of asteroid motion is 14.2 degrees
The recommended exposure time corresponds to 1.2 km per image.
The 1-sigma error in the time of the event is 2.8 seconds.
The 1-sigma cross-track error in the shadow position is 12.6 km.
The sky-plane scale is 3405.9 km/arcsec.
Diameter estimates:
55.0 km assuming a 5% albedo, maximum of 5.8 sec for a central chord
22.4 km assuming a 30% albedo, maximum of 2.4 sec for a central chord
Cross-track diameter of 50.0 km used for deployment plan.
Star training set for 11509_Thersilochos, (2026/10/25 02:45UT) Object RA Dec mag sep mel Betelgeuse 05:56:37.5 +07:24:35 0.4 4.86 73 Alhena 06:39:15.6 +16:22:27 1.9 10.44 82 PPM 150217 06:18:25.3 +07:02:27 6.4 0.77 78 PPM 150176 06:17:02.9 +07:38:30 7.5 0.21 78 PPM 150165 06:16:44.8 +07:26:00 9.7 0.20 78 11509_Thersilo 06:16:13.5 +07:34:56 15.6 78 Positions are for equinox of date
Star training set for 11509_Thersilochos, (2026/10/25 02:45UT) Object RA Dec mag sep mel Betelgeuse 05:55:10.3 +07:24:26 0.4 4.86 73 Alhena 06:37:42.8 +16:23:56 1.9 10.44 82 PPM 150217 06:16:58.4 +07:03:08 6.4 0.77 78 PPM 150176 06:15:35.7 +07:39:08 7.5 0.21 78 PPM 150165 06:15:17.7 +07:26:37 9.7 0.20 78 11509_Thersilo 06:14:46.2 +07:35:33 15.6 78 Positions are for J2000