Occultation event with (19725) 99WT4, event index number 1075
Regions able to see the event: SAmericaN
Geocentric closest approach at 2025/06/20 21:57:28 UTC
J2000 position of star is 09:13:57.3 +25:06:49
Equinox of date position of star is 09:15:26.2 +25:00:26
Star is 105 degrees from the moon. Moon is 27% illuminated.
Stellar brightness G=12.2, apparent brightess of occulting body is G=16.4
Use an exposure time of 0.12 seconds with the standard RECON-QHY system.
SNR of 18.7 per integration for unocculted signal
Expected flux drop is 98% with SNR of 18.3 for the occulted depth (per occulted point)
Apparent velocity is 34.8 km/sec on the sky relative to the star, or, 30.9 arcsec/hr.
Position angle of asteroid motion is 337.4 degrees
The recommended exposure time corresponds to 4.2 km per image.
The 1-sigma error in the time of the event is 1.3 seconds.
The 1-sigma cross-track error in the shadow position is 24.1 km.
The sky-plane scale is 4060.8 km/arcsec.
Diameter estimates:
40.7 km assuming a 5% albedo, aximum of 1.2 sec for a central chord
16.6 km assuming a 30% albedo, maximum of 0.5 sec for a central chord
Cross-track diameter of 40.7 km used for deployment plan.
Star training set for 19725_99WT4, (2025/06/20 21:57UT) Object RA Dec mag sep mel Regulus 10:09:43.5 +11:50:30 1.3 18.39 122 69Nu Cnc 09:04:13.3 +24:21:03 5.4 2.63 103 PPM 099418 09:15:56.6 +24:54:15 8.0 0.15 105 PPM 099406 09:15:10.8 +25:08:52 9.0 0.15 105 19725_99WT4 09:15:26.2 +25:00:26 16.4 105 Positions are for equinox of date
Star training set for 19725_99WT4, (2025/06/20 21:57UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 18.39 122 69Nu Cnc 09:02:44.2 +24:27:10 5.4 2.63 103 PPM 099418 09:14:27.8 +25:00:39 8.0 0.15 105 PPM 099406 09:13:41.9 +25:15:15 9.0 0.15 105 19725_99WT4 09:13:57.3 +25:06:49 16.4 105 Positions are for J2000