Occultation event with (1437) Diomedes, event index number 3659
Regions able to see the event: SAfrica
Geocentric closest approach at 2026/04/19 22:11:52 UTC
J2000 position of star is 13:07:48.1 -33:20:41
Equinox of date position of star is 13:09:15.8 -33:29:04
Star is 142 degrees from the moon. Moon is 9% illuminated.
Stellar brightness G=16.2, apparent brightess of occulting body is G=13.2
Use an exposure time of 1.70 seconds with the standard RECON-QHY system.
SNR of 3.1 per integration for unocculted signal
Expected flux drop is 6% with SNR of 0.2 for the occulted depth (per occulted point)
Apparent velocity is 17.1 km/sec on the sky relative to the star, or, 19.2 arcsec/hr.
Position angle of asteroid motion is 110.2 degrees
The recommended exposure time corresponds to 29.0 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 22.1 km.
The sky-plane scale is 3204.0 km/arcsec.
Diameter estimates:
140.6 km assuming a 5% albedo, maximum of 8.2 sec for a central chord
57.4 km assuming a 30% albedo, maximum of 3.4 sec for a central chord
Cross-track diameter of 117.8 km used for deployment plan.
Star training set for 1437_Diomedes, (2026/04/19 22:12UT) Object RA Dec mag sep mel Spica 13:26:34.9 -11:17:52 1.0 22.54 140 Iot Cen 13:22:05.1 -36:51:01 2.8 4.26 144 PPM 290865 13:02:30.2 -33:45:54 6.3 1.43 140 PPM 291027 13:10:28.6 -33:38:29 7.4 0.30 142 PPM 291000 13:09:05.0 -33:17:23 9.4 0.20 142 PPM 290992 13:08:57.3 -33:36:32 10.2 0.14 142 1437_Diomedes 13:09:15.8 -33:29:04 13.2 142 Positions are for equinox of date
Star training set for 1437_Diomedes, (2026/04/19 22:12UT) Object RA Dec mag sep mel Spica 13:25:11.5 -11:09:41 1.0 22.54 140 Iot Cen 13:20:35.1 -36:42:46 2.8 4.26 144 PPM 290865 13:01:03.1 -33:37:26 6.3 1.43 140 PPM 291027 13:09:00.8 -33:30:06 7.4 0.30 142 PPM 291000 13:07:37.4 -33:08:59 9.4 0.20 142 PPM 290992 13:07:29.6 -33:28:08 10.2 0.14 142 1437_Diomedes 13:07:48.1 -33:20:41 13.2 142 Positions are for J2000