Occultation event with (4791) Iphidamas, event index number 1542
Regions able to see the event: Japan
Geocentric closest approach at 2025/11/18 18:40:03 UTC
J2000 position of star is 01:11:21.1 +33:13:20
Equinox of date position of star is 01:12:47.7 +33:21:33
Star is 158 degrees from the moon. Moon is 2% illuminated.
Stellar brightness G=12.9, apparent brightess of occulting body is G=14.9
Use an exposure time of 0.12 seconds with the standard RECON-QHY system.
SNR of 11.5 per integration for unocculted signal
Expected flux drop is 86% with SNR of 9.9 for the occulted depth (per occulted point)
Apparent velocity is 16.5 km/sec on the sky relative to the star, or, 19.9 arcsec/hr.
Position angle of asteroid motion is 31.9 degrees
The recommended exposure time corresponds to 2.0 km per image.
The 1-sigma error in the time of the event is 1.5 seconds.
The 1-sigma cross-track error in the shadow position is 10.4 km.
The sky-plane scale is 2980.4 km/arcsec.
Diameter estimates:
59.2 km assuming a 5% albedo, aximum of 3.6 sec for a central chord
24.1 km assuming a 30% albedo, maximum of 1.5 sec for a central chord
Cross-track diameter of 49.5 km used for deployment plan.
Star training set for 4791_Iphidamas, (2025/11/18 18:40UT) Object RA Dec mag sep mel Aldebaran 04:37:24.5 +16:33:33 0.8 48.78 149 57Gam1And 02:05:30.0 +42:27:09 2.3 13.78 156 PPM 066072 01:14:43.3 +34:14:06 6.5 0.96 158 PPM 066000 01:10:40.0 +34:04:44 7.6 0.84 157 PPM 066066 01:14:27.7 +33:29:13 9.4 0.37 158 4791_Iphidamas 01:12:47.7 +33:21:33 14.9 158 Positions are for equinox of date
Star training set for 4791_Iphidamas, (2025/11/18 18:40UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 48.78 149 57Gam1And 02:03:54.1 +42:19:46 2.3 13.78 156 PPM 066072 01:13:16.2 +34:05:54 6.5 0.96 158 PPM 066000 01:09:13.4 +33:56:29 7.6 0.84 157 PPM 066066 01:13:00.9 +33:21:01 9.4 0.37 158 4791_Iphidamas 01:11:21.1 +33:13:20 14.9 158 Positions are for J2000