Occultation event with (588) Achilles, event index number 1726
Regions able to see the event: SAmericaN
Geocentric closest approach at 2025/12/27 06:17:06 UTC
J2000 position of star is 12:53:51.2 -14:15:11
Equinox of date position of star is 12:55:13.2 -14:23:37
Star is 160 degrees from the moon. Moon is 44% illuminated.
Stellar brightness G=11.5, apparent brightess of occulting body is G=13.9
Use an exposure time of 0.12 seconds with the standard RECON-QHY system.
SNR of 28.1 per integration for unocculted signal
Expected flux drop is 90% with SNR of 25.4 for the occulted depth (per occulted point)
Apparent velocity is 19.5 km/sec on the sky relative to the star, or, 18.2 arcsec/hr.
Position angle of asteroid motion is 128.4 degrees
The recommended exposure time corresponds to 2.3 km per image.
The 1-sigma error in the time of the event is 1.7 seconds.
The 1-sigma cross-track error in the shadow position is 14.8 km.
The sky-plane scale is 3854.3 km/arcsec.
Diameter estimates:
136.1 km assuming a 5% albedo, aximum of 7.0 sec for a central chord
55.6 km assuming a 30% albedo, maximum of 2.8 sec for a central chord
Cross-track diameter of 130.1 km used for deployment plan.
Star training set for 588_Achilles, (2025/12/27 06:17UT) Object RA Dec mag sep mel Spica 13:26:34.0 -11:17:46 1.0 8.24 155 PPM 226546 12:57:15.5 -15:28:02 6.2 1.18 159 PPM 226479 12:54:31.6 -15:06:22 7.9 0.73 160 PPM 226494 12:55:00.5 -14:36:10 9.4 0.22 160 588_Achilles 12:55:13.2 -14:23:37 13.9 160 Positions are for equinox of date
Star training set for 588_Achilles, (2025/12/27 06:17UT) Object RA Dec mag sep mel Spica 13:25:11.5 -11:09:41 1.0 8.24 155 PPM 226546 12:55:53.2 -15:19:37 6.2 1.18 159 PPM 226479 12:53:09.5 -14:57:55 7.9 0.73 160 PPM 226494 12:53:38.5 -14:27:44 9.4 0.22 160 588_Achilles 12:53:51.2 -14:15:11 13.9 160 Positions are for J2000