Occultation event with (9857) Hecamede, event index number 3548
Regions able to see the event: SAmericaS
Geocentric closest approach at 2026/03/31 02:27:35 UTC
J2000 position of star is 11:38:35.8 -23:23:24
Equinox of date position of star is 11:39:55.2 -23:32:08
Star is 29 degrees from the moon. Moon is 96% illuminated.
Stellar brightness G=16.2, apparent brightess of occulting body is G=15.3
Use an exposure time of 0.75 seconds with the standard RECON-QHY system.
SNR of 3.0 per integration for unocculted signal
Expected flux drop is 30% with SNR of 0.9 for the occulted depth (per occulted point)
Apparent velocity is 16.8 km/sec on the sky relative to the star, or, 19.5 arcsec/hr.
Position angle of asteroid motion is 114.6 degrees
The recommended exposure time corresponds to 12.6 km per image.
The 1-sigma error in the time of the event is 1.6 seconds.
The 1-sigma cross-track error in the shadow position is 18.6 km.
The sky-plane scale is 3102.0 km/arcsec.
Diameter estimates:
51.5 km assuming a 5% albedo, maximum of 3.1 sec for a central chord
21.0 km assuming a 30% albedo, maximum of 1.3 sec for a central chord
Cross-track diameter of 49.5 km used for deployment plan.
Star training set for 9857_Hecamede, (2026/03/31 02:28UT) Object RA Dec mag sep mel Spica 13:26:34.8 -11:17:51 1.0 28.16 37 4Gam Crv 12:17:09.6 -17:41:15 2.6 10.49 27 PPM 259219 11:38:19.1 -23:05:35 6.5 0.58 28 PPM 259232 11:38:45.5 -23:22:16 8.3 0.31 28 PPM 259251 11:39:44.9 -23:49:23 9.5 0.29 29 9857_Hecamede 11:39:55.2 -23:32:08 15.3 29 Positions are for equinox of date
Star training set for 9857_Hecamede, (2026/03/31 02:28UT) Object RA Dec mag sep mel Spica 13:25:11.5 -11:09:41 1.0 28.16 37 4Gam Crv 12:15:48.1 -17:32:30 2.6 10.49 27 PPM 259219 11:36:59.8 -22:56:52 6.5 0.58 28 PPM 259232 11:37:26.3 -23:13:32 8.3 0.31 28 PPM 259251 11:38:25.6 -23:40:40 9.5 0.29 29 9857_Hecamede 11:38:35.8 -23:23:24 15.3 29 Positions are for J2000