Occultation event with (19725) 99WT4, event index number 1737
Regions able to see the event: Europe
Geocentric closest approach at 2025/12/31 03:40:29 UTC
J2000 position of star is 11:39:01.3 +12:55:10
Equinox of date position of star is 11:40:22.0 +12:46:31
Star is 115 degrees from the moon. Moon is 85% illuminated.
Stellar brightness G=15.1, apparent brightess of occulting body is G=16.1
Use an exposure time of 1.00 seconds with the standard RECON-QHY system.
SNR of 9.7 per integration for unocculted signal
Expected flux drop is 72% with SNR of 7.0 for the occulted depth (per occulted point)
Apparent velocity is 4.4 km/sec on the sky relative to the star, or, 4.8 arcsec/hr.
Position angle of asteroid motion is 63.9 degrees
The recommended exposure time corresponds to 4.4 km per image.
The 1-sigma error in the time of the event is 0.6 seconds.
The 1-sigma cross-track error in the shadow position is 40.3 km.
The sky-plane scale is 3347.7 km/arcsec.
Diameter estimates:
41.1 km assuming a 5% albedo, aximum of 9.3 sec for a central chord
16.8 km assuming a 30% albedo, maximum of 3.8 sec for a central chord
Cross-track diameter of 31.7 km used for deployment plan.
Star training set for 19725_99WT4, (2025/12/31 03:40UT) Object RA Dec mag sep mel Regulus 10:09:45.2 +11:50:21 1.3 22.15 96 Denebola 11:50:23.1 +14:25:36 2.1 2.94 116 PPM 128566 11:49:58.9 +14:08:23 6.0 2.71 116 PPM 128419 11:39:21.1 +12:48:47 8.4 0.25 114 19725_99WT4 11:40:22.0 +12:46:31 16.1 115 Positions are for equinox of date
Star training set for 19725_99WT4, (2025/12/31 03:40UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 22.15 96 Denebola 11:49:02.7 +14:34:16 2.1 2.94 116 PPM 128566 11:48:38.5 +14:17:03 6.0 2.71 116 PPM 128419 11:38:00.5 +12:57:25 8.4 0.25 114 19725_99WT4 11:39:01.3 +12:55:10 16.1 115 Positions are for J2000