Occultation event with (11509) Thersilochos, event index number 4759
Regions able to see the event: SAfrica
Geocentric closest approach at 2026/11/18 20:50:06 UTC
J2000 position of star is 06:09:14.7 +06:07:02
Equinox of date position of star is 06:10:41.2 +06:06:39
Star is 110 degrees from the moon. Moon is 64% illuminated.
Stellar brightness G=16.6, apparent brightess of occulting body is G=15.4
Use an exposure time of 1.25 seconds with the standard RECON-QHY system.
SNR of 3.0 per integration for unocculted signal
Expected flux drop is 24% with SNR of 0.7 for the occulted depth (per occulted point)
Apparent velocity is 14.2 km/sec on the sky relative to the star, or, 15.8 arcsec/hr.
Position angle of asteroid motion is 60.3 degrees
The recommended exposure time corresponds to 17.7 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 27.6 km.
The sky-plane scale is 3221.9 km/arcsec.
Diameter estimates:
55.0 km assuming a 5% albedo, maximum of 3.9 sec for a central chord
22.4 km assuming a 30% albedo, maximum of 1.6 sec for a central chord
Cross-track diameter of 50.0 km used for deployment plan.
Star training set for 11509_Thersilochos, (2026/11/18 20:50UT) Object RA Dec mag sep mel Betelgeuse 05:56:37.7 +07:24:35 0.4 3.72 106 Bellatrix 05:26:34.5 +06:22:18 1.6 10.97 99 63 Ori 06:06:24.2 +05:24:58 6.4 1.27 109 PPM 149989 06:10:49.9 +06:16:07 7.7 0.16 110 11509_Thersilo 06:10:41.2 +06:06:39 15.4 110 Positions are for equinox of date
Star training set for 11509_Thersilochos, (2026/11/18 20:50UT) Object RA Dec mag sep mel Betelgeuse 05:55:10.3 +07:24:26 0.4 3.72 106 Bellatrix 05:25:07.8 +06:20:58 1.6 10.97 99 63 Ori 06:04:58.1 +05:25:12 6.4 1.27 109 PPM 149989 06:09:23.3 +06:16:31 7.7 0.16 110 11509_Thersilo 06:09:14.7 +06:07:02 15.4 110 Positions are for J2000