Occultation event with (9799) Thronium, event index number 1020
Regions able to see the event: SAmericaN
Geocentric closest approach at 2025/05/30 23:58:13 UTC
J2000 position of star is 08:33:18.3 -08:28:08
Equinox of date position of star is 08:34:32.4 -08:33:25
Star is 32 degrees from the moon. Moon is 20% illuminated.
Stellar brightness G=16.4, apparent brightess of occulting body is G=15.5
Use an exposure time of 0.95 seconds with the standard RECON-QHY system.
SNR of 3.1 per integration for unocculted signal
Expected flux drop is 31% with SNR of 1.0 for the occulted depth (per occulted point)
Apparent velocity is 26.0 km/sec on the sky relative to the star, or, 22.7 arcsec/hr.
Position angle of asteroid motion is 3.4 degrees
The recommended exposure time corresponds to 24.7 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 22.9 km.
The sky-plane scale is 4111.6 km/arcsec.
Diameter estimates:
70.8 km assuming a 5% albedo, aximum of 2.7 sec for a central chord
28.9 km assuming a 30% albedo, maximum of 1.1 sec for a central chord
Cross-track diameter of 70.8 km used for deployment plan.
Star training set for 9799_Thronium, (2025/05/30 23:58UT) Object RA Dec mag sep mel Sirius 06:46:16.0 -16:45:09 -1.5 27.62 47 Alphard 09:28:50.2 -08:46:12 2.0 13.42 36 3 Hya 08:36:42.6 -08:04:17 6.2 0.72 32 PPM 191424 08:32:46.5 -08:28:09 8.3 0.45 32 PPM 191469 08:35:15.6 -08:30:36 9.4 0.18 32 9799_Thronium 08:34:32.4 -08:33:25 15.5 32 Positions are for equinox of date
Star training set for 9799_Thronium, (2025/05/30 23:58UT) Object RA Dec mag sep mel Sirius 06:45:07.9 -16:43:28 -1.5 27.62 47 Alphard 09:27:35.2 -08:39:30 2.0 13.42 36 3 Hya 08:35:28.2 -07:58:56 6.2 0.72 32 PPM 191424 08:31:32.3 -08:22:55 8.3 0.45 32 PPM 191469 08:34:01.4 -08:25:18 9.4 0.18 32 9799_Thronium 08:33:18.3 -08:28:08 15.5 32 Positions are for J2000