Occultation event with (12242) Koon, event index number 1334
Regions able to see the event: SAmericaN
Geocentric closest approach at 2025/10/04 04:27:18 UTC
J2000 position of star is 04:15:52.2 +12:56:32
Equinox of date position of star is 04:17:18.6 +13:00:18
Star is 93 degrees from the moon. Moon is 88% illuminated.
Stellar brightness G=13.5, apparent brightess of occulting body is G=16.1
Use an exposure time of 0.17 seconds with the standard RECON-QHY system.
SNR of 9.6 per integration for unocculted signal
Expected flux drop is 92% with SNR of 8.8 for the occulted depth (per occulted point)
Apparent velocity is 11.6 km/sec on the sky relative to the star, or, 12.8 arcsec/hr.
Position angle of asteroid motion is 25.7 degrees
The recommended exposure time corresponds to 2.0 km per image.
The 1-sigma error in the time of the event is 2.0 seconds.
The 1-sigma cross-track error in the shadow position is 21.6 km.
The sky-plane scale is 3260.0 km/arcsec.
Diameter estimates:
39.8 km assuming a 5% albedo, aximum of 3.4 sec for a central chord
16.2 km assuming a 30% albedo, maximum of 1.4 sec for a central chord
Cross-track diameter of 37.9 km used for deployment plan.
Star training set for 12242_Koon, (2025/10/04 04:27UT) Object RA Dec mag sep mel Aldebaran 04:37:24.1 +16:33:32 0.8 6.02 98 Bellatrix 05:26:30.8 +06:22:15 1.6 18.29 108 57 Tau 04:21:24.9 +14:05:44 5.9 1.48 94 PPM 119715 04:15:16.1 +12:49:04 7.3 0.53 92 PPM 119747 04:18:12.1 +13:01:12 9.9 0.22 93 12242_Koon 04:17:18.6 +13:00:18 16.1 93 Positions are for equinox of date
Star training set for 12242_Koon, (2025/10/04 04:27UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 6.02 98 Bellatrix 05:25:07.8 +06:20:58 1.6 18.29 108 57 Tau 04:19:57.9 +14:02:07 5.9 1.48 94 PPM 119715 04:13:49.9 +12:45:15 7.3 0.53 92 PPM 119747 04:16:45.7 +12:57:28 9.9 0.22 93 12242_Koon 04:15:52.2 +12:56:32 16.1 93 Positions are for J2000