Occultation event with (5144) Achates, event index number 1696
Regions able to see the event: SAmericaN
Geocentric closest approach at 2025/12/18 22:39:02 UTC
J2000 position of star is 02:53:55.1 +27:29:34
Equinox of date position of star is 02:55:27.4 +27:35:50
Star is 154 degrees from the moon. Moon is 1% illuminated.
Stellar brightness G=13.7, apparent brightess of occulting body is G=14.6
Use an exposure time of 0.20 seconds with the standard RECON-QHY system.
SNR of 9.3 per integration for unocculted signal
Expected flux drop is 70% with SNR of 6.5 for the occulted depth (per occulted point)
Apparent velocity is 12.3 km/sec on the sky relative to the star, or, 12.8 arcsec/hr.
Position angle of asteroid motion is 57.4 degrees
The recommended exposure time corresponds to 2.5 km per image.
The 1-sigma error in the time of the event is 1.9 seconds.
The 1-sigma cross-track error in the shadow position is 19.2 km.
The sky-plane scale is 3459.8 km/arcsec.
Diameter estimates:
87.5 km assuming a 5% albedo, aximum of 7.1 sec for a central chord
35.7 km assuming a 30% albedo, maximum of 2.9 sec for a central chord
Cross-track diameter of 81.0 km used for deployment plan.
Star training set for 5144_Achates, (2025/12/18 22:39UT) Object RA Dec mag sep mel Aldebaran 04:37:24.8 +16:33:34 0.8 26.00 168 Hamal 02:08:38.6 +23:35:02 2.0 11.29 143 49 Ari 03:03:26.3 +26:33:48 6.0 2.06 156 PPM 092073 02:56:54.6 +27:49:33 7.0 0.39 154 PPM 092041 02:54:34.7 +27:38:04 10.0 0.20 154 5144_Achates 02:55:27.4 +27:35:50 14.6 154 Positions are for equinox of date
Star training set for 5144_Achates, (2025/12/18 22:39UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 26.00 168 Hamal 02:07:10.8 +23:27:41 2.0 11.29 143 49 Ari 03:01:54.1 +26:27:44 6.0 2.06 156 PPM 092073 02:55:22.0 +27:43:19 7.0 0.39 154 PPM 092041 02:53:02.4 +27:31:46 10.0 0.20 154 5144_Achates 02:53:55.1 +27:29:34 14.6 154 Positions are for J2000