Occultation event with (4057) Demophon, event index number 3671
Regions able to see the event: SAmericaS
Geocentric closest approach at 2026/04/22 04:38:40 UTC
J2000 position of star is 11:23:45.7 +05:35:43
Equinox of date position of star is 11:25:07.2 +05:27:02
Star is 72 degrees from the moon. Moon is 29% illuminated.
Stellar brightness G=15.2, apparent brightess of occulting body is G=15.4
Use an exposure time of 1.20 seconds with the standard RECON-QHY system.
SNR of 9.7 per integration for unocculted signal
Expected flux drop is 55% with SNR of 5.3 for the occulted depth (per occulted point)
Apparent velocity is 9.2 km/sec on the sky relative to the star, or, 10.4 arcsec/hr.
Position angle of asteroid motion is 106.4 degrees
The recommended exposure time corresponds to 11.0 km per image.
The 1-sigma error in the time of the event is 2.9 seconds.
The 1-sigma cross-track error in the shadow position is 29.2 km.
The sky-plane scale is 3184.7 km/arcsec.
Diameter estimates:
53.2 km assuming a 5% albedo, maximum of 5.8 sec for a central chord
21.7 km assuming a 30% albedo, maximum of 2.4 sec for a central chord
Cross-track diameter of 45.7 km used for deployment plan.
Star training set for 4057_Demophon, (2026/04/22 04:39UT) Object RA Dec mag sep mel Regulus 10:09:46.2 +11:50:15 1.3 19.68 53 Denebola 11:50:24.0 +14:25:30 2.1 10.92 74 77Sig Leo 11:22:29.5 +05:53:05 4.0 0.78 72 PPM 157764 11:22:20.3 +04:44:09 7.8 0.99 72 PPM 157830 11:26:32.6 +05:35:40 8.6 0.38 73 PPM 157802 11:24:39.6 +05:31:42 10.6 0.14 72 4057_Demophon 11:25:07.2 +05:27:02 15.4 73 Positions are for equinox of date
Star training set for 4057_Demophon, (2026/04/22 04:39UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 19.68 53 Denebola 11:49:02.7 +14:34:16 2.1 10.92 74 77Sig Leo 11:21:08.0 +06:01:45 4.0 0.78 72 PPM 157764 11:20:59.0 +04:52:49 7.8 0.99 72 PPM 157830 11:25:11.2 +05:44:21 8.6 0.38 73 PPM 157802 11:23:18.2 +05:40:23 10.6 0.14 72 4057_Demophon 11:23:45.7 +05:35:43 15.4 72 Positions are for J2000