Occultation event with (4057) Demophon, event index number 3691
Regions able to see the event: SAmericaS
Geocentric closest approach at 2026/04/28 01:37:47 UTC
J2000 position of star is 11:22:23.2 +05:41:21
Equinox of date position of star is 11:23:44.7 +05:32:40
Star is 8 degrees from the moon. Moon is 87% illuminated.
Stellar brightness G=14.5, apparent brightess of occulting body is G=15.5
Use an exposure time of 0.50 seconds with the standard RECON-QHY system.
SNR of 9.5 per integration for unocculted signal
Expected flux drop is 71% with SNR of 6.7 for the occulted depth (per occulted point)
Apparent velocity is 7.0 km/sec on the sky relative to the star, or, 7.8 arcsec/hr.
Position angle of asteroid motion is 103.9 degrees
The recommended exposure time corresponds to 3.5 km per image.
The 1-sigma error in the time of the event is 3.6 seconds.
The 1-sigma cross-track error in the shadow position is 30.7 km.
The sky-plane scale is 3235.0 km/arcsec.
Diameter estimates:
53.2 km assuming a 5% albedo, maximum of 7.6 sec for a central chord
21.7 km assuming a 30% albedo, maximum of 3.1 sec for a central chord
Cross-track diameter of 45.7 km used for deployment plan.
Star training set for 4057_Demophon, (2026/04/28 01:38UT) Object RA Dec mag sep mel Regulus 10:09:46.3 +11:50:15 1.3 19.32 26 Denebola 11:50:24.1 +14:25:29 2.1 11.04 15 77Sig Leo 11:22:29.6 +05:53:05 4.0 0.46 8 PPM 157764 11:22:20.4 +04:44:09 7.8 0.88 7 PPM 157770 11:22:38.7 +05:35:48 9.4 0.28 8 PPM 157802 11:24:39.7 +05:31:42 10.6 0.23 7 4057_Demophon 11:23:44.7 +05:32:40 15.5 7 Positions are for equinox of date
Star training set for 4057_Demophon, (2026/04/28 01:38UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 19.32 26 Denebola 11:49:02.7 +14:34:16 2.1 11.04 15 77Sig Leo 11:21:08.0 +06:01:45 4.0 0.46 8 PPM 157764 11:20:59.0 +04:52:49 7.8 0.88 7 PPM 157770 11:21:17.2 +05:44:29 9.4 0.28 8 PPM 157802 11:23:18.2 +05:40:23 10.6 0.23 7 4057_Demophon 11:22:23.2 +05:41:21 15.5 8 Positions are for J2000