Occultation event with (9799) Thronium, event index number 891
Regions able to see the event: SAfrica
Geocentric closest approach at 2025/04/08 18:46:27 UTC
J2000 position of star is 08:13:16.9 -10:14:26
Equinox of date position of star is 08:14:29.5 -10:19:06
Star is 39 degrees from the moon. Moon is 84% illuminated.
Stellar brightness G=13.7, apparent brightess of occulting body is G=15.2
Use an exposure time of 0.20 seconds with the standard RECON-QHY system.
SNR of 9.2 per integration for unocculted signal
Expected flux drop is 80% with SNR of 7.4 for the occulted depth (per occulted point)
Apparent velocity is 9.4 km/sec on the sky relative to the star, or, 9.4 arcsec/hr.
The recommended exposure time corresponds to 1.9 km per image.
The 1-sigma error in the time of the event is 2.8 seconds.
The 1-sigma cross-track error in the shadow position is 29.7 km.
The sky-plane scale is 3594.6 km/arcsec.
Diameter estimates:
70.8 km assuming a 5% albedo, aximum of 7.5 sec for a central chord
28.9 km assuming a 30% albedo, maximum of 3.1 sec for a central chord
Cross-track diameter of 70.8 km used for deployment plan.
Star training set for 9799_Thronium, (2025/04/08 18:46UT) Object RA Dec mag sep mel Sirius 06:46:15.7 -16:45:09 -1.5 22.37 61 15Rho Pup 08:08:37.2 -24:22:43 2.8 14.13 49 PPM 219950 08:20:27.7 -10:14:46 6.3 1.47 38 PPM 219798 08:13:36.7 -10:54:37 8.2 0.63 40 PPM 219835 08:15:09.9 -10:22:10 8.9 0.17 39 9799_Thronium 08:14:29.5 -10:19:06 15.2 39 Positions are for equinox of date
Star training set for 9799_Thronium, (2025/04/08 18:46UT) Object RA Dec mag sep mel Sirius 06:45:07.9 -16:43:28 -1.5 22.37 61 15Rho Pup 08:07:32.5 -24:18:14 2.8 14.13 49 PPM 219950 08:19:15.0 -10:09:56 6.3 1.47 38 PPM 219798 08:12:24.4 -10:50:00 8.2 0.63 40 PPM 219835 08:13:57.3 -10:17:30 8.9 0.17 39 9799_Thronium 08:13:16.9 -10:14:26 15.2 39 Positions are for J2000