Occultation event with (4057) Demophon, event index number 3468
Regions able to see the event: SAmericaN
Geocentric closest approach at 2026/03/20 00:46:36 UTC
J2000 position of star is 11:37:13.2 +04:24:20
Equinox of date position of star is 11:38:34.1 +04:15:37
Star is 160 degrees from the moon. Moon is 1% illuminated.
Stellar brightness G=15.1, apparent brightess of occulting body is G=14.9
Use an exposure time of 0.65 seconds with the standard RECON-QHY system.
SNR of 6.9 per integration for unocculted signal
Expected flux drop is 45% with SNR of 3.1 for the occulted depth (per occulted point)
Apparent velocity is 16.7 km/sec on the sky relative to the star, or, 19.9 arcsec/hr.
Position angle of asteroid motion is 111.1 degrees
The recommended exposure time corresponds to 10.8 km per image.
The 1-sigma error in the time of the event is 1.8 seconds.
The 1-sigma cross-track error in the shadow position is 27.4 km.
The sky-plane scale is 3016.1 km/arcsec.
Diameter estimates:
53.2 km assuming a 5% albedo, maximum of 3.2 sec for a central chord
21.7 km assuming a 30% albedo, maximum of 1.3 sec for a central chord
Cross-track diameter of 45.7 km used for deployment plan.
Star training set for 4057_Demophon, (2026/03/20 00:47UT) Object RA Dec mag sep mel Regulus 10:09:45.9 +11:50:17 1.3 23.23 138 Denebola 11:50:23.7 +14:25:32 2.1 10.57 155 89 Leo 11:35:42.5 +02:54:51 6.2 1.52 160 PPM 158062 11:40:05.3 +04:16:53 8.3 0.38 161 PPM 158046 11:39:08.9 +04:10:40 10.3 0.17 160 4057_Demophon 11:38:34.1 +04:15:37 14.9 161 Positions are for equinox of date
Star training set for 4057_Demophon, (2026/03/20 00:47UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 23.23 138 Denebola 11:49:02.7 +14:34:16 2.1 10.57 155 89 Leo 11:34:21.6 +03:03:34 6.2 1.52 160 PPM 158062 11:38:44.5 +04:25:36 8.3 0.38 161 PPM 158046 11:37:48.0 +04:19:23 10.3 0.17 160 4057_Demophon 11:37:13.2 +04:24:20 14.9 160 Positions are for J2000