Occultation event with (12242) Koon, event index number 4012
Regions able to see the event: SAfrica
Geocentric closest approach at 2026/08/15 02:47:25 UTC
J2000 position of star is 05:53:21.8 +06:25:13
Equinox of date position of star is 05:54:47.7 +06:25:26
Star is 85 degrees from the moon. Moon is 7% illuminated.
Stellar brightness G=14.1, 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 9.5 per integration for unocculted signal
Expected flux drop is 92% with SNR of 8.7 for the occulted depth (per occulted point)
Apparent velocity is 31.0 km/sec on the sky relative to the star, or, 26.5 arcsec/hr.
Position angle of asteroid motion is 111.1 degrees
The recommended exposure time corresponds to 9.3 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 24.2 km.
The sky-plane scale is 4210.8 km/arcsec.
Diameter estimates:
39.8 km assuming a 5% albedo, maximum of 1.3 sec for a central chord
16.2 km assuming a 30% albedo, maximum of 0.5 sec for a central chord
Cross-track diameter of 37.9 km used for deployment plan.
Star training set for 12242_Koon, (2026/08/15 02:47UT) Object RA Dec mag sep mel Betelgeuse 05:56:36.8 +07:24:35 0.4 1.08 84 Bellatrix 05:26:33.6 +06:22:18 1.6 7.01 92 PPM 149639 05:56:20.9 +05:51:49 6.4 0.68 84 PPM 149601 05:54:52.2 +06:15:34 7.9 0.17 85 12242_Koon 05:54:47.7 +06:25:26 16.8 84 Positions are for equinox of date
Star training set for 12242_Koon, (2026/08/15 02:47UT) Object RA Dec mag sep mel Betelgeuse 05:55:10.3 +07:24:26 0.4 1.08 84 Bellatrix 05:25:07.8 +06:20:58 1.6 7.01 92 PPM 149639 05:54:55.4 +05:51:39 6.4 0.68 84 PPM 149601 05:53:26.4 +06:15:21 7.9 0.17 85 12242_Koon 05:53:21.8 +06:25:13 16.8 85 Positions are for J2000