Occultation event with (12242) Koon, event index number 1211
Regions able to see the event: SAmericaN
Geocentric closest approach at 2025/08/06 05:57:10 UTC
J2000 position of star is 04:02:48.2 +16:05:04
Equinox of date position of star is 04:04:15.5 +16:09:13
Star is 144 degrees from the moon. Moon is 90% illuminated.
Stellar brightness G=15.4, apparent brightess of occulting body is G=16.6
Use an exposure time of 0.40 seconds with the standard RECON-QHY system.
SNR of 4.2 per integration for unocculted signal
Expected flux drop is 75% with SNR of 3.1 for the occulted depth (per occulted point)
Apparent velocity is 21.8 km/sec on the sky relative to the star, or, 20.3 arcsec/hr.
Position angle of asteroid motion is 101.7 degrees
The recommended exposure time corresponds to 8.7 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 26.9 km.
The sky-plane scale is 3873.1 km/arcsec.
Diameter estimates:
39.8 km assuming a 5% albedo, aximum of 1.8 sec for a central chord
16.2 km assuming a 30% albedo, maximum of 0.7 sec for a central chord
Cross-track diameter of 37.9 km used for deployment plan.
Star training set for 12242_Koon, (2025/08/06 05:57UT) Object RA Dec mag sep mel Aldebaran 04:37:23.5 +16:33:31 0.8 7.96 151 44Zet Per 03:55:44.9 +31:57:27 2.8 15.92 146 PPM 119638 04:09:09.2 +15:13:45 6.1 1.50 145 PPM 119538 04:02:11.4 +15:32:43 8.2 0.79 143 PPM 119558 04:03:36.8 +15:36:37 9.4 0.57 144 PPM 119546 04:02:50.4 +16:13:11 10.8 0.35 144 12242_Koon 04:04:15.5 +16:09:13 16.6 144 Positions are for equinox of date
Star training set for 12242_Koon, (2025/08/06 05:57UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 7.96 151 44Zet Per 03:54:07.9 +31:53:01 2.8 15.92 146 PPM 119638 04:07:42.2 +15:09:45 6.1 1.50 145 PPM 119538 04:00:44.5 +15:28:30 8.2 0.79 143 PPM 119558 04:02:09.7 +15:32:26 9.4 0.57 144 PPM 119546 04:01:23.1 +16:08:58 10.8 0.35 144 12242_Koon 04:02:48.2 +16:05:04 16.6 144 Positions are for J2000