Occultation event with (12242) Koon, event index number 4869
Regions able to see the event: Europe,SAmericaN
Geocentric closest approach at 2026/11/25 03:18:38 UTC
J2000 position of star is 06:09:12.7 -02:25:51
Equinox of date position of star is 06:10:33.9 -02:26:14
Star is 38 degrees from the moon. Moon is 99% illuminated.
Stellar brightness G=15.9, apparent brightess of occulting body is G=16.1
Use an exposure time of 0.50 seconds with the standard RECON-QHY system.
SNR of 3.2 per integration for unocculted signal
Expected flux drop is 56% with SNR of 1.8 for the occulted depth (per occulted point)
Apparent velocity is 17.8 km/sec on the sky relative to the star, or, 19.5 arcsec/hr.
Position angle of asteroid motion is 55.3 degrees
The recommended exposure time corresponds to 8.9 km per image.
The 1-sigma error in the time of the event is 0.5 seconds.
The 1-sigma cross-track error in the shadow position is 31.2 km.
The sky-plane scale is 3289.0 km/arcsec.
Diameter estimates:
39.8 km assuming a 5% albedo, maximum of 2.2 sec for a central chord
16.2 km assuming a 30% albedo, maximum of 0.9 sec for a central chord
Cross-track diameter of 37.9 km used for deployment plan.
Star training set for 12242_Koon, (2026/11/25 03:19UT) Object RA Dec mag sep mel Betelgeuse 05:56:37.7 +07:24:35 0.4 10.44 28 Saiph 05:49:02.0 -09:39:44 2.1 8.99 41 PPM 188936 06:15:14.5 -03:45:03 5.8 1.76 39 PPM 176136 06:10:18.2 -02:02:37 7.9 0.40 37 PPM 176133 06:10:04.1 -02:30:27 8.7 0.14 38 12242_Koon 06:10:33.9 -02:26:14 16.1 38 Positions are for equinox of date
Star training set for 12242_Koon, (2026/11/25 03:19UT) Object RA Dec mag sep mel Betelgeuse 05:55:10.3 +07:24:26 0.4 10.44 28 Saiph 05:47:45.4 -09:40:11 2.1 8.99 41 PPM 188936 06:13:54.2 -03:44:28 5.8 1.76 39 PPM 176136 06:08:56.7 -02:02:14 7.9 0.40 37 PPM 176133 06:08:43.0 -02:30:05 8.7 0.14 38 12242_Koon 06:09:12.7 -02:25:51 16.1 38 Positions are for J2000