Occultation event with (11509) Thersilochos, event index number 4486
Regions able to see the event: Australia
Geocentric closest approach at 2026/10/25 19:38:21 UTC
J2000 position of star is 06:14:43.2 +07:32:50
Equinox of date position of star is 06:16:10.4 +07:32:14
Star is 68 degrees from the moon. Moon is 100% illuminated.
Stellar brightness G=16.1, apparent brightess of occulting body is G=15.6
Use an exposure time of 1.30 seconds with the standard RECON-QHY system.
SNR of 5.0 per integration for unocculted signal
Expected flux drop is 39% with SNR of 2.0 for the occulted depth (per occulted point)
Apparent velocity is 9.5 km/sec on the sky relative to the star, or, 10.0 arcsec/hr.
Position angle of asteroid motion is 16.1 degrees
The recommended exposure time corresponds to 12.3 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 13.5 km.
The sky-plane scale is 3399.6 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 19:38UT) Object RA Dec mag sep mel Betelgeuse 05:56:37.5 +07:24:35 0.4 4.85 64 Alhena 06:39:15.6 +16:22:27 1.9 10.48 72 PPM 150217 06:18:25.3 +07:02:27 6.4 0.75 69 PPM 150176 06:17:02.9 +07:38:30 7.5 0.24 69 PPM 150165 06:16:44.8 +07:26:00 9.7 0.18 69 11509_Thersilo 06:16:10.4 +07:32:14 15.6 69 Positions are for equinox of date
Star training set for 11509_Thersilochos, (2026/10/25 19:38UT) Object RA Dec mag sep mel Betelgeuse 05:55:10.3 +07:24:26 0.4 4.85 64 Alhena 06:37:42.8 +16:23:56 1.9 10.48 72 PPM 150217 06:16:58.4 +07:03:08 6.4 0.75 69 PPM 150176 06:15:35.7 +07:39:08 7.5 0.24 69 PPM 150165 06:15:17.7 +07:26:37 9.7 0.18 69 11509_Thersilo 06:14:43.2 +07:32:50 15.6 68 Positions are for J2000