Occultation event with (9799) Thronium, event index number 1034
Regions able to see the event: SAfrica
Geocentric closest approach at 2025/06/06 18:50:45 UTC
J2000 position of star is 08:37:36.7 -08:27:51
Equinox of date position of star is 08:38:51.0 -08:33:16
Star is 73 degrees from the moon. Moon is 82% illuminated.
Stellar brightness G=16.3, apparent brightess of occulting body is G=15.5
Use an exposure time of 0.80 seconds with the standard RECON-QHY system.
SNR of 3.1 per integration for unocculted signal
Expected flux drop is 34% with SNR of 1.0 for the occulted depth (per occulted point)
Apparent velocity is 28.2 km/sec on the sky relative to the star, or, 24.3 arcsec/hr.
Position angle of asteroid motion is 355.5 degrees
The recommended exposure time corresponds to 22.5 km per image.
The 1-sigma error in the time of the event is 1.2 seconds.
The 1-sigma cross-track error in the shadow position is 23.1 km.
The sky-plane scale is 4172.6 km/arcsec.
Diameter estimates:
70.8 km assuming a 5% albedo, aximum of 2.5 sec for a central chord
28.9 km assuming a 30% albedo, maximum of 1.0 sec for a central chord
Cross-track diameter of 70.8 km used for deployment plan.
Star training set for 9799_Thronium, (2025/06/06 18:51UT) Object RA Dec mag sep mel Sirius 06:46:16.1 -16:45:09 -1.5 28.62 98 Alphard 09:28:50.2 -08:46:12 2.0 12.36 60 3 Hya 08:36:42.7 -08:04:17 6.2 0.72 73 PPM 191536 08:39:13.4 -08:49:30 8.2 0.29 72 PPM 191541 08:39:33.2 -08:39:23 8.9 0.20 72 9799_Thronium 08:38:51.0 -08:33:16 15.5 72 Positions are for equinox of date
Star training set for 9799_Thronium, (2025/06/06 18:51UT) Object RA Dec mag sep mel Sirius 06:45:07.9 -16:43:28 -1.5 28.62 98 Alphard 09:27:35.2 -08:39:30 2.0 12.36 60 3 Hya 08:35:28.2 -07:58:56 6.2 0.72 73 PPM 191536 08:37:59.2 -08:44:04 8.2 0.29 72 PPM 191541 08:38:19.0 -08:33:57 8.9 0.20 72 9799_Thronium 08:37:36.7 -08:27:51 15.5 73 Positions are for J2000