Occultation event with (15527) 99YY2, event index number 1720
Regions able to see the event: Australia
Geocentric closest approach at 2025/12/25 19:51:42 UTC
J2000 position of star is 11:24:27.2 -00:55:26
Equinox of date position of star is 11:25:47.0 -01:04:01
Star is 167 degrees from the moon. Moon is 30% illuminated.
Stellar brightness G=16.7, apparent brightess of occulting body is G=17.1
Use an exposure time of 2.00 seconds with the standard RECON-QHY system.
SNR of 4.4 per integration for unocculted signal
Expected flux drop is 60% with SNR of 2.6 for the occulted depth (per occulted point)
Apparent velocity is 4.4 km/sec on the sky relative to the star, or, 3.8 arcsec/hr.
Position angle of asteroid motion is 88.5 degrees
The recommended exposure time corresponds to 8.9 km per image.
The 1-sigma error in the time of the event is 0.2 seconds.
The 1-sigma cross-track error in the shadow position is 31.9 km.
The sky-plane scale is 4163.0 km/arcsec.
Diameter estimates:
38.7 km assuming a 5% albedo, aximum of 8.8 sec for a central chord
15.8 km assuming a 30% albedo, maximum of 3.6 sec for a central chord
Cross-track diameter of 36.4 km used for deployment plan.
Star training set for 15527_99YY2, (2025/12/25 19:52UT) Object RA Dec mag sep mel Regulus 10:09:45.2 +11:50:21 1.3 22.87 170 Denebola 11:50:23.0 +14:25:36 2.1 16.65 163 79 Leo 11:25:22.4 +01:15:53 6.4 2.33 169 PPM 178489 11:27:19.1 -01:13:17 8.2 0.41 167 PPM 178486 11:27:07.9 -00:54:36 9.6 0.37 167 PPM 178477 11:24:37.3 -01:10:23 10.2 0.31 167 15527_99YY2 11:25:47.0 -01:04:01 17.1 167 Positions are for equinox of date
Star training set for 15527_99YY2, (2025/12/25 19:52UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 22.87 170 Denebola 11:49:02.7 +14:34:16 2.1 16.65 163 79 Leo 11:24:02.3 +01:24:28 6.4 2.33 169 PPM 178489 11:25:59.3 -01:04:42 8.2 0.41 167 PPM 178486 11:25:48.0 -00:46:01 9.6 0.37 167 PPM 178477 11:23:17.5 -01:01:48 10.2 0.31 167 15527_99YY2 11:24:27.2 -00:55:26 17.1 167 Positions are for J2000