Occultation event with (12242) Koon, event index number 4066
Regions able to see the event: SAmericaN
Geocentric closest approach at 2026/08/21 06:31:37 UTC
J2000 position of star is 05:57:19.1 +06:00:44
Equinox of date position of star is 05:58:44.8 +06:00:49
Star is 151 degrees from the moon. Moon is 61% illuminated.
Stellar brightness G=14.3, apparent brightess of occulting body is G=16.8
Use an exposure time of 0.30 seconds with the standard RECON-QHY system.
SNR of 8.4 per integration for unocculted signal
Expected flux drop is 91% with SNR of 7.6 for the occulted depth (per occulted point)
Apparent velocity is 29.3 km/sec on the sky relative to the star, or, 25.3 arcsec/hr.
Position angle of asteroid motion is 114.0 degrees
The recommended exposure time corresponds to 8.8 km per image.
The 1-sigma error in the time of the event is 0.8 seconds.
The 1-sigma cross-track error in the shadow position is 24.0 km.
The sky-plane scale is 4156.6 km/arcsec.
Diameter estimates:
39.8 km assuming a 5% albedo, maximum of 1.4 sec for a central chord
16.2 km assuming a 30% albedo, maximum of 0.6 sec for a central chord
Cross-track diameter of 37.9 km used for deployment plan.
Star training set for 12242_Koon, (2026/08/21 06:32UT) Object RA Dec mag sep mel Betelgeuse 05:56:36.9 +07:24:35 0.4 1.49 152 Bellatrix 05:26:33.7 +06:22:18 1.6 8.01 156 PPM 149639 05:56:21.0 +05:51:49 6.4 0.61 151 PPM 149688 05:58:56.0 +06:23:33 8.1 0.38 151 PPM 149687 05:58:55.6 +05:49:09 10.1 0.20 151 12242_Koon 05:58:44.8 +06:00:49 16.8 151 Positions are for equinox of date
Star training set for 12242_Koon, (2026/08/21 06:32UT) Object RA Dec mag sep mel Betelgeuse 05:55:10.3 +07:24:26 0.4 1.49 152 Bellatrix 05:25:07.8 +06:20:58 1.6 8.01 156 PPM 149639 05:54:55.4 +05:51:39 6.4 0.61 151 PPM 149688 05:57:30.1 +06:23:28 8.1 0.38 151 PPM 149687 05:57:30.0 +05:49:05 10.1 0.20 151 12242_Koon 05:57:19.1 +06:00:44 16.8 151 Positions are for J2000