Occultation event with (19725) 99WT4, event index number 1701
Regions able to see the event: SAmericaS
Geocentric closest approach at 2025/12/20 07:26:11 UTC
J2000 position of star is 11:37:00.2 +12:50:46
Equinox of date position of star is 11:38:20.8 +12:42:08
Star is 102 degrees from the moon. Moon is 0% illuminated.
Stellar brightness G=14.6, apparent brightess of occulting body is G=16.2
Use an exposure time of 0.55 seconds with the standard RECON-QHY system.
SNR of 9.6 per integration for unocculted signal
Expected flux drop is 81% with SNR of 7.8 for the occulted depth (per occulted point)
Apparent velocity is 8.9 km/sec on the sky relative to the star, or, 9.3 arcsec/hr.
Position angle of asteroid motion is 90.4 degrees
The recommended exposure time corresponds to 4.9 km per image.
The 1-sigma error in the time of the event is 2.2 seconds.
The 1-sigma cross-track error in the shadow position is 33.8 km.
The sky-plane scale is 3463.5 km/arcsec.
Diameter estimates:
41.1 km assuming a 5% albedo, aximum of 4.6 sec for a central chord
16.8 km assuming a 30% albedo, maximum of 1.9 sec for a central chord
Cross-track diameter of 31.7 km used for deployment plan.
Star training set for 19725_99WT4, (2025/12/20 07:26UT) Object RA Dec mag sep mel Regulus 10:09:45.1 +11:50:21 1.3 21.65 121 Denebola 11:50:23.0 +14:25:37 2.1 3.40 100 PPM 128566 11:49:58.8 +14:08:23 6.0 3.17 100 PPM 128419 11:39:21.0 +12:48:47 8.4 0.27 102 PPM 128388 11:37:27.2 +12:42:41 8.8 0.22 102 19725_99WT4 11:38:20.8 +12:42:08 16.2 102 Positions are for equinox of date
Star training set for 19725_99WT4, (2025/12/20 07:26UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 21.65 121 Denebola 11:49:02.7 +14:34:16 2.1 3.40 100 PPM 128566 11:48:38.5 +14:17:03 6.0 3.17 100 PPM 128419 11:38:00.5 +12:57:25 8.4 0.27 102 PPM 128388 11:36:06.5 +12:51:18 8.8 0.22 102 19725_99WT4 11:37:00.2 +12:50:46 16.2 102 Positions are for J2000