Occultation event with (17171) 99NB38, event index number 1275
Regions able to see the event: Europe
Geocentric closest approach at 2025/09/09 22:53:55 UTC
J2000 position of star is 03:20:05.7 +46:42:19
Equinox of date position of star is 03:21:52.8 +46:47:48
Star is 48 degrees from the moon. Moon is 93% illuminated.
Stellar brightness G=16.3, apparent brightess of occulting body is G=16.0
Use an exposure time of 0.80 seconds with the standard RECON-QHY system.
SNR of 3.2 per integration for unocculted signal
Expected flux drop is 44% with SNR of 1.4 for the occulted depth (per occulted point)
Apparent velocity is 12.2 km/sec on the sky relative to the star, or, 12.7 arcsec/hr.
Position angle of asteroid motion is 0.7 degrees
The recommended exposure time corresponds to 9.7 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 5.1 km.
The sky-plane scale is 3458.1 km/arcsec.
Diameter estimates:
46.1 km assuming a 5% albedo, aximum of 3.8 sec for a central chord
18.8 km assuming a 30% albedo, maximum of 1.5 sec for a central chord
Cross-track diameter of 40.9 km used for deployment plan.
Star training set for 17171_99NB38, (2025/09/09 22:54UT) Object RA Dec mag sep mel Aldebaran 04:37:23.9 +16:33:32 0.8 34.04 53 Mirphak 03:26:10.3 +49:57:02 1.8 3.23 51 PPM 046236 03:31:14.6 +47:01:29 6.1 1.62 49 PPM 046045 03:22:01.1 +46:52:21 8.5 0.08 48 17171_99NB38 03:21:52.8 +46:47:48 16.0 48 Positions are for equinox of date
Star training set for 17171_99NB38, (2025/09/09 22:54UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 34.04 53 Mirphak 03:24:19.4 +49:51:40 1.8 3.23 51 PPM 046236 03:29:26.4 +46:56:16 6.1 1.62 49 PPM 046045 03:20:14.0 +46:46:52 8.5 0.08 48 17171_99NB38 03:20:05.7 +46:42:19 16.0 48 Positions are for J2000