Occultation event with (17171) 99NB38, event index number 1647
Regions able to see the event: Europe
Geocentric closest approach at 2025/12/06 16:32:25 UTC
J2000 position of star is 02:33:13.8 +47:00:51
Equinox of date position of star is 02:34:56.7 +47:07:38
Star is 51 degrees from the moon. Moon is 95% illuminated.
Stellar brightness G=13.8, apparent brightess of occulting body is G=15.7
Use an exposure time of 0.20 seconds with the standard RECON-QHY system.
SNR of 9.0 per integration for unocculted signal
Expected flux drop is 85% with SNR of 7.7 for the occulted depth (per occulted point)
Apparent velocity is 16.1 km/sec on the sky relative to the star, or, 18.3 arcsec/hr.
Position angle of asteroid motion is 45.5 degrees
The recommended exposure time corresponds to 3.2 km per image.
The 1-sigma error in the time of the event is 1.6 seconds.
The 1-sigma cross-track error in the shadow position is 12.3 km.
The sky-plane scale is 3159.5 km/arcsec.
Diameter estimates:
46.1 km assuming a 5% albedo, aximum of 2.9 sec for a central chord
18.8 km assuming a 30% albedo, maximum of 1.2 sec for a central chord
Cross-track diameter of 40.9 km used for deployment plan.
Star training set for 17171_99NB38, (2025/12/06 16:32UT) Object RA Dec mag sep mel Aldebaran 04:37:24.7 +16:33:33 0.8 39.64 31 57Gam1And 02:05:30.2 +42:27:10 2.3 7.00 57 PPM 045001 02:22:23.2 +47:25:42 6.0 2.15 54 PPM 045216 02:36:10.7 +46:48:21 8.2 0.38 51 PPM 045163 02:32:58.7 +47:09:22 8.8 0.34 52 17171_99NB38 02:34:56.7 +47:07:38 15.7 51 Positions are for equinox of date
Star training set for 17171_99NB38, (2025/12/06 16:32UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 39.64 31 57Gam1And 02:03:54.1 +42:19:46 2.3 7.00 57 PPM 045001 02:20:41.7 +47:18:38 6.0 2.15 54 PPM 045216 02:34:27.9 +46:41:36 8.2 0.38 51 PPM 045163 02:31:16.0 +47:02:33 8.8 0.34 52 17171_99NB38 02:33:13.8 +47:00:51 15.7 51 Positions are for J2000