Occultation event with (4057) Demophon, event index number 962
Regions able to see the event: SAmericaS
Geocentric closest approach at 2025/05/10 00:49:08 UTC
J2000 position of star is 09:09:57.8 +18:53:17
Equinox of date position of star is 09:11:23.5 +18:47:01
Star is 66 degrees from the moon. Moon is 94% illuminated.
Stellar brightness G=16.4, apparent brightess of occulting body is G=15.7
Use an exposure time of 0.90 seconds with the standard RECON-QHY system.
SNR of 3.1 per integration for unocculted signal
Expected flux drop is 35% with SNR of 1.1 for the occulted depth (per occulted point)
Apparent velocity is 16.1 km/sec on the sky relative to the star, or, 16.4 arcsec/hr.
Position angle of asteroid motion is 330.1 degrees
The recommended exposure time corresponds to 14.5 km per image.
The 1-sigma error in the time of the event is 3.1 seconds.
The 1-sigma cross-track error in the shadow position is 32.6 km.
The sky-plane scale is 3527.2 km/arcsec.
Diameter estimates:
52.7 km assuming a 5% albedo, aximum of 3.3 sec for a central chord
21.5 km assuming a 30% albedo, maximum of 1.3 sec for a central chord
Cross-track diameter of 52.7 km used for deployment plan.
Star training set for 4057_Demophon, (2025/05/10 00:49UT) Object RA Dec mag sep mel Regulus 10:09:43.2 +11:50:32 1.3 15.67 51 PPM 099404 09:15:03.9 +21:10:38 6.1 2.54 66 PPM 126094 09:06:55.7 +19:20:00 8.1 1.19 68 PPM 126170 09:11:25.6 +18:51:00 8.7 0.07 66 4057_Demophon 09:11:23.5 +18:47:01 15.7 66 Positions are for equinox of date
Star training set for 4057_Demophon, (2025/05/10 00:49UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 15.67 51 PPM 099404 09:13:37.2 +21:16:59 6.1 2.54 66 PPM 126094 09:05:29.5 +19:26:08 8.1 1.19 68 PPM 126170 09:09:59.9 +18:57:16 8.7 0.07 66 4057_Demophon 09:09:57.8 +18:53:17 15.7 66 Positions are for J2000