Occultation event with (18493) Demoleon, event index number 1306
Regions able to see the event: SAfrica
Geocentric closest approach at 2025/09/22 22:49:44 UTC
J2000 position of star is 02:05:18.8 +15:35:39
Equinox of date position of star is 02:06:43.0 +15:42:59
Star is 158 degrees from the moon. Moon is 1% illuminated.
Stellar brightness G=14.5, apparent brightess of occulting body is G=15.9
Use an exposure time of 0.45 seconds with the standard RECON-QHY system.
SNR of 9.5 per integration for unocculted signal
Expected flux drop is 79% with SNR of 7.5 for the occulted depth (per occulted point)
Apparent velocity is 12.7 km/sec on the sky relative to the star, or, 14.6 arcsec/hr.
Position angle of asteroid motion is 55.7 degrees
The recommended exposure time corresponds to 5.7 km per image.
The 1-sigma error in the time of the event is 1.5 seconds.
The 1-sigma cross-track error in the shadow position is 25.9 km.
The sky-plane scale is 3127.1 km/arcsec.
Diameter estimates:
40.5 km assuming a 5% albedo, aximum of 3.2 sec for a central chord
16.6 km assuming a 30% albedo, maximum of 1.3 sec for a central chord
Cross-track diameter of 33.5 km used for deployment plan.
Star training set for 18493_Demoleon, (2025/09/22 22:50UT) Object RA Dec mag sep mel Aldebaran 04:37:24.0 +16:33:32 0.8 36.14 123 6Bet Ari 01:56:04.0 +20:55:58 2.6 5.80 158 19 Ari 02:14:27.8 +15:23:57 5.7 1.89 157 PPM 117935 02:06:48.1 +15:39:35 8.4 0.06 158 18493_Demoleon 02:06:43.0 +15:42:59 15.9 158 Positions are for equinox of date
Star training set for 18493_Demoleon, (2025/09/22 22:50UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 36.14 123 6Bet Ari 01:54:38.6 +20:48:26 2.6 5.80 158 19 Ari 02:13:03.5 +15:16:47 5.7 1.89 157 PPM 117935 02:05:24.0 +15:32:16 8.4 0.06 158 18493_Demoleon 02:05:18.8 +15:35:39 15.9 158 Positions are for J2000