Occultation event with (9142) Rhesus, event index number 1231
Regions able to see the event: SAmericaS
Geocentric closest approach at 2025/08/15 09:15:45 UTC
J2000 position of star is 03:12:31.9 +04:34:18
Equinox of date position of star is 03:13:52.7 +04:40:00
Star is 18 degrees from the moon. Moon is 60% illuminated.
Stellar brightness G=15.0, apparent brightess of occulting body is G=16.1
Use an exposure time of 0.85 seconds with the standard RECON-QHY system.
SNR of 9.9 per integration for unocculted signal
Expected flux drop is 74% with SNR of 7.3 for the occulted depth (per occulted point)
Apparent velocity is 11.9 km/sec on the sky relative to the star, or, 12.4 arcsec/hr.
Position angle of asteroid motion is 108.6 degrees
The recommended exposure time corresponds to 10.1 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 27.6 km.
The sky-plane scale is 3451.2 km/arcsec.
Diameter estimates:
43.7 km assuming a 5% albedo, aximum of 3.7 sec for a central chord
17.8 km assuming a 30% albedo, maximum of 1.5 sec for a central chord
Cross-track diameter of 42.3 km used for deployment plan.
Star training set for 9142_Rhesus, (2025/08/15 09:16UT) Object RA Dec mag sep mel Aldebaran 04:37:23.6 +16:33:31 0.8 23.68 30 Menkar 03:03:37.3 +04:11:19 2.5 2.60 17 PPM 146333 03:13:48.1 +06:45:21 5.6 2.09 16 PPM 146427 03:19:27.5 +05:03:42 8.0 1.44 18 PPM 146324 03:12:55.3 +04:49:07 8.6 0.28 18 9142_Rhesus 03:13:52.7 +04:40:00 16.1 18 Positions are for equinox of date
Star training set for 9142_Rhesus, (2025/08/15 09:16UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 23.68 30 Menkar 03:02:16.8 +04:05:21 2.5 2.60 17 PPM 146333 03:12:26.3 +06:39:39 5.6 2.09 16 PPM 146427 03:18:06.4 +04:58:10 8.0 1.44 18 PPM 146324 03:11:34.4 +04:43:23 8.6 0.28 18 9142_Rhesus 03:12:31.9 +04:34:18 16.1 18 Positions are for J2000