Occultation event with (4057) Demophon, event index number 1712
Regions able to see the event: SAmericaN
Geocentric closest approach at 2025/12/23 07:53:41 UTC
J2000 position of star is 11:55:16.5 +02:28:49
Equinox of date position of star is 11:56:36.4 +02:20:08
Star is 130 degrees from the moon. Moon is 10% illuminated.
Stellar brightness G=14.9, apparent brightess of occulting body is G=15.8
Use an exposure time of 0.80 seconds with the standard RECON-QHY system.
SNR of 10.0 per integration for unocculted signal
Expected flux drop is 69% with SNR of 6.9 for the occulted depth (per occulted point)
Apparent velocity is 10.9 km/sec on the sky relative to the star, or, 11.0 arcsec/hr.
Position angle of asteroid motion is 111.7 degrees
The recommended exposure time corresponds to 8.7 km per image.
The 1-sigma error in the time of the event is 2.7 seconds.
The 1-sigma cross-track error in the shadow position is 26.4 km.
The sky-plane scale is 3566.3 km/arcsec.
Diameter estimates:
53.2 km assuming a 5% albedo, aximum of 4.9 sec for a central chord
21.7 km assuming a 30% albedo, maximum of 2.0 sec for a central chord
Cross-track diameter of 45.7 km used for deployment plan.
Star training set for 4057_Demophon, (2025/12/23 07:54UT) Object RA Dec mag sep mel Spica 13:26:33.9 -11:17:46 1.0 26.19 104 Denebola 11:50:23.0 +14:25:36 2.1 12.19 136 5Bet Vir 11:52:02.9 +01:37:06 3.6 1.35 131 PPM 158328 11:56:26.9 +03:04:27 8.0 0.74 131 PPM 158331 11:56:46.0 +02:08:23 9.3 0.20 130 PPM 158324 11:56:16.2 +02:30:23 11.8 0.19 131 4057_Demophon 11:56:36.4 +02:20:08 15.8 130 Positions are for equinox of date
Star training set for 4057_Demophon, (2025/12/23 07:54UT) Object RA Dec mag sep mel Spica 13:25:11.5 -11:09:41 1.0 26.19 104 Denebola 11:49:02.7 +14:34:16 2.1 12.19 136 5Bet Vir 11:50:43.0 +01:45:46 3.6 1.35 131 PPM 158328 11:55:07.0 +03:13:07 8.0 0.74 131 PPM 158331 11:55:26.1 +02:17:04 9.3 0.20 130 PPM 158324 11:54:56.2 +02:39:03 11.8 0.19 131 4057_Demophon 11:55:16.5 +02:28:49 15.8 130 Positions are for J2000