Occultation event with (39264) 00YQ139, event index number 983
Regions able to see the event: SAmericaN,SAmericaS
Geocentric closest approach at 2025/05/18 00:18:13 UTC
J2000 position of star is 09:53:31.3 -01:32:23
Equinox of date position of star is 09:54:48.9 -01:39:37
Star is 142 degrees from the moon. Moon is 75% illuminated.
Stellar brightness G=15.9, apparent brightess of occulting body is G=16.5
Use an exposure time of 0.75 seconds with the standard RECON-QHY system.
SNR of 4.2 per integration for unocculted signal
Expected flux drop is 64% with SNR of 2.7 for the occulted depth (per occulted point)
Apparent velocity is 13.5 km/sec on the sky relative to the star, or, 13.0 arcsec/hr.
Position angle of asteroid motion is 12.8 degrees
The recommended exposure time corresponds to 10.2 km per image.
The 1-sigma error in the time of the event is 4.0 seconds.
The 1-sigma cross-track error in the shadow position is 15.6 km.
The sky-plane scale is 3746.2 km/arcsec.
Diameter estimates:
41.1 km assuming a 5% albedo, aximum of 3.0 sec for a central chord
16.8 km assuming a 30% albedo, maximum of 1.2 sec for a central chord
Cross-track diameter of 41.1 km used for deployment plan.
Star training set for 39264_00YQ139, (2025/05/18 00:18UT) Object RA Dec mag sep mel Regulus 10:09:43.2 +11:50:32 1.3 14.00 147 Alphard 09:28:50.1 -08:46:11 2.0 9.61 140 35Iot Hya 09:41:09.1 -01:15:33 3.9 3.44 145 PPM 178019 09:55:48.1 -01:23:29 8.4 0.36 142 PPM 178013 09:54:50.2 -01:44:11 9.2 0.08 142 39264_00YQ139 09:54:48.9 -01:39:37 16.5 142 Positions are for equinox of date
Star training set for 39264_00YQ139, (2025/05/18 00:18UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 14.00 147 Alphard 09:27:35.2 -08:39:30 2.0 9.61 140 35Iot Hya 09:39:51.4 -01:08:36 3.9 3.44 145 PPM 178019 09:54:30.5 -01:16:14 8.4 0.36 142 PPM 178013 09:53:32.6 -01:36:57 9.2 0.08 142 39264_00YQ139 09:53:31.3 -01:32:23 16.5 142 Positions are for J2000