Occultation event with (15440) Eioneus, event index number 1633
Regions able to see the event: Europe
Geocentric closest approach at 2025/12/03 03:47:55 UTC
J2000 position of star is 11:07:19.2 +21:36:14
Equinox of date position of star is 11:08:41.9 +21:27:47
Star is 112 degrees from the moon. Moon is 95% illuminated.
Stellar brightness G=13.5, apparent brightess of occulting body is G=15.3
Use an exposure time of 0.17 seconds with the standard RECON-QHY system.
SNR of 9.7 per integration for unocculted signal
Expected flux drop is 84% with SNR of 8.1 for the occulted depth (per occulted point)
Apparent velocity is 16.4 km/sec on the sky relative to the star, or, 15.7 arcsec/hr.
Position angle of asteroid motion is 63.7 degrees
The recommended exposure time corresponds to 2.8 km per image.
The 1-sigma error in the time of the event is 1.1 seconds.
The 1-sigma cross-track error in the shadow position is 38.3 km.
The sky-plane scale is 3771.3 km/arcsec.
Diameter estimates:
72.4 km assuming a 5% albedo, aximum of 4.4 sec for a central chord
29.6 km assuming a 30% albedo, maximum of 1.8 sec for a central chord
Cross-track diameter of 62.5 km used for deployment plan.
Star training set for 15440_Eioneus, (2025/12/03 03:48UT) Object RA Dec mag sep mel Regulus 10:09:45.0 +11:50:22 1.3 17.07 104 68Del Leo 11:15:29.0 +20:22:53 2.6 1.92 114 64 Leo 11:09:02.7 +23:10:59 6.4 1.72 111 PPM 100955 11:12:14.1 +21:11:40 7.8 0.87 113 PPM 100900 11:08:15.8 +21:25:01 9.6 0.11 112 15440_Eioneus 11:08:41.9 +21:27:47 15.3 112 Positions are for equinox of date
Star training set for 15440_Eioneus, (2025/12/03 03:48UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 17.07 104 68Del Leo 11:14:06.7 +20:31:22 2.6 1.92 114 64 Leo 11:07:39.7 +23:19:25 6.4 1.72 111 PPM 100955 11:10:51.6 +21:20:08 7.8 0.87 113 PPM 100900 11:06:53.0 +21:33:27 9.6 0.11 112 15440_Eioneus 11:07:19.2 +21:36:14 15.3 112 Positions are for J2000