Occultation event with (5144) Achates, event index number 1202
Regions able to see the event: NMexico
Geocentric closest approach at 2025/07/21 11:37:09 UTC
J2000 position of star is 03:18:51.7 +26:50:42
Equinox of date position of star is 03:20:23.6 +26:56:11
Star is 21 degrees from the moon. Moon is 14% illuminated.
Stellar brightness G=16.2, apparent brightess of occulting body is G=15.0
Use an exposure time of 0.85 seconds with the standard RECON-QHY system.
SNR of 3.2 per integration for unocculted signal
Expected flux drop is 25% with SNR of 0.8 for the occulted depth (per occulted point)
Apparent velocity is 24.5 km/sec on the sky relative to the star, or, 21.6 arcsec/hr.
The recommended exposure time corresponds to 20.8 km per image.
The 1-sigma error in the time of the event is 1.3 seconds.
The 1-sigma cross-track error in the shadow position is 17.5 km.
The sky-plane scale is 4087.0 km/arcsec.
Diameter estimates:
87.5 km assuming a 5% albedo, aximum of 3.6 sec for a central chord
35.7 km assuming a 30% albedo, maximum of 1.5 sec for a central chord
Cross-track diameter of 87.5 km used for deployment plan.
Star training set for 5144_Achates, (2025/07/21 11:37UT) Object RA Dec mag sep mel Aldebaran 04:37:23.4 +16:33:31 0.8 20.63 12 44Zet Per 03:55:44.7 +31:57:27 2.8 9.18 13 56 Ari 03:13:45.9 +27:21:06 5.6 1.53 22 59 Ari 03:21:27.8 +27:09:42 6.7 0.33 21 PPM 092358 03:19:03.4 +26:59:12 9.4 0.30 21 PPM 092386 03:20:31.6 +26:47:08 10.3 0.15 21 5144_Achates 03:20:23.6 +26:56:11 15.0 21 Positions are for equinox of date
Star training set for 5144_Achates, (2025/07/21 11:37UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 20.63 12 44Zet Per 03:54:07.9 +31:53:01 2.8 9.18 13 56 Ari 03:12:14.2 +27:15:25 5.6 1.53 22 59 Ari 03:19:55.8 +27:04:14 6.7 0.33 21 PPM 092358 03:17:31.6 +26:53:40 9.4 0.30 21 PPM 092386 03:18:59.8 +26:41:39 10.3 0.15 21 5144_Achates 03:18:51.7 +26:50:42 15.0 21 Positions are for J2000