Occultation event with (9142) Rhesus, event index number 4060
Regions able to see the event: SAfrica
Geocentric closest approach at 2026/08/21 01:38:01 UTC
J2000 position of star is 05:09:58.1 +11:06:36
Equinox of date position of star is 05:11:26.8 +11:08:30
Star is 161 degrees from the moon. Moon is 59% illuminated.
Stellar brightness G=16.3, apparent brightess of occulting body is G=16.5
Use an exposure time of 0.80 seconds with the standard RECON-QHY system.
SNR of 3.1 per integration for unocculted signal
Expected flux drop is 54% with SNR of 1.7 for the occulted depth (per occulted point)
Apparent velocity is 22.1 km/sec on the sky relative to the star, or, 19.7 arcsec/hr.
Position angle of asteroid motion is 96.6 degrees
The recommended exposure time corresponds to 17.7 km per image.
The 1-sigma error in the time of the event is 0.1 seconds.
The 1-sigma cross-track error in the shadow position is 28.0 km.
The sky-plane scale is 4036.8 km/arcsec.
Diameter estimates:
43.7 km assuming a 5% albedo, maximum of 2.0 sec for a central chord
17.8 km assuming a 30% albedo, maximum of 0.8 sec for a central chord
Cross-track diameter of 42.3 km used for deployment plan.
Star training set for 9142_Rhesus, (2026/08/21 01:38UT) Object RA Dec mag sep mel Aldebaran 04:37:27.1 +16:33:38 0.8 9.87 169 Bellatrix 05:26:33.7 +06:22:18 1.6 6.06 155 16 Ori 05:10:47.7 +09:51:42 5.4 1.29 160 PPM 120663 05:11:27.7 +10:55:26 8.4 0.22 161 9142_Rhesus 05:11:26.8 +11:08:30 16.5 161 Positions are for equinox of date
Star training set for 9142_Rhesus, (2026/08/21 01:38UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 9.87 169 Bellatrix 05:25:07.8 +06:20:58 1.6 6.06 155 16 Ori 05:09:19.7 +09:49:46 5.4 1.29 160 PPM 120663 05:09:59.1 +10:53:32 8.4 0.22 161 9142_Rhesus 05:09:58.1 +11:06:36 16.5 161 Positions are for J2000