Occultation event with (12242) Koon, event index number 1223
Regions able to see the event: SAmericaN
Geocentric closest approach at 2025/08/12 07:47:34 UTC
J2000 position of star is 04:05:58.8 +15:54:07
Equinox of date position of star is 04:07:26.1 +15:58:11
Star is 64 degrees from the moon. Moon is 89% illuminated.
Stellar brightness G=11.6, apparent brightess of occulting body is G=16.5
Use an exposure time of 0.12 seconds with the standard RECON-QHY system.
SNR of 27.3 per integration for unocculted signal
Expected flux drop is 99% with SNR of 27.0 for the occulted depth (per occulted point)
Apparent velocity is 19.6 km/sec on the sky relative to the star, or, 18.5 arcsec/hr.
Position angle of asteroid motion is 105.4 degrees
The recommended exposure time corresponds to 2.3 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 25.7 km.
The sky-plane scale is 3808.9 km/arcsec.
Diameter estimates:
39.8 km assuming a 5% albedo, aximum of 2.0 sec for a central chord
16.2 km assuming a 30% albedo, maximum of 0.8 sec for a central chord
Cross-track diameter of 37.9 km used for deployment plan.
Star training set for 12242_Koon, (2025/08/12 07:48UT) Object RA Dec mag sep mel Aldebaran 04:37:23.6 +16:33:31 0.8 7.21 72 44Zet Per 03:55:44.9 +31:57:27 2.8 16.21 65 PPM 119638 04:09:09.2 +15:13:46 6.1 0.85 65 PPM 119621 04:07:43.6 +15:45:56 8.2 0.22 64 12242_Koon 04:07:26.1 +15:58:11 16.5 65 Positions are for equinox of date
Star training set for 12242_Koon, (2025/08/12 07:48UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 7.21 72 44Zet Per 03:54:07.9 +31:53:01 2.8 16.21 65 PPM 119638 04:07:42.2 +15:09:45 6.1 0.85 65 PPM 119621 04:06:16.4 +15:41:53 8.2 0.22 64 12242_Koon 04:05:58.8 +15:54:07 16.5 64 Positions are for J2000