Occultation event with (17171) 99NB38, event index number 1632
Regions able to see the event: Europe
Geocentric closest approach at 2025/12/02 22:10:26 UTC
J2000 position of star is 02:35:15.3 +47:19:41
Equinox of date position of star is 02:36:58.7 +47:26:25
Star is 28 degrees from the moon. Moon is 94% illuminated.
Stellar brightness G=15.2, apparent brightess of occulting body is G=15.6
Use an exposure time of 0.60 seconds with the standard RECON-QHY system.
SNR of 6.5 per integration for unocculted signal
Expected flux drop is 60% with SNR of 3.9 for the occulted depth (per occulted point)
Apparent velocity is 16.4 km/sec on the sky relative to the star, or, 18.8 arcsec/hr.
Position angle of asteroid motion is 49.8 degrees
The recommended exposure time corresponds to 9.9 km per image.
The 1-sigma error in the time of the event is 1.5 seconds.
The 1-sigma cross-track error in the shadow position is 14.0 km.
The sky-plane scale is 3144.5 km/arcsec.
Diameter estimates:
46.1 km assuming a 5% albedo, aximum of 2.8 sec for a central chord
18.8 km assuming a 30% albedo, maximum of 1.1 sec for a central chord
Cross-track diameter of 40.9 km used for deployment plan.
Star training set for 17171_99NB38, (2025/12/02 22:10UT) Object RA Dec mag sep mel Aldebaran 04:37:24.7 +16:33:33 0.8 39.58 30 57Gam1And 02:05:30.1 +42:27:10 2.3 7.47 24 PPM 045321 02:42:07.0 +49:40:13 6.5 2.39 30 PPM 045216 02:36:10.7 +46:48:21 8.2 0.65 27 PPM 045232 02:37:02.0 +47:09:17 9.3 0.29 28 17171_99NB38 02:36:58.7 +47:26:25 15.6 28 Positions are for equinox of date
Star training set for 17171_99NB38, (2025/12/02 22:10UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 39.58 30 57Gam1And 02:03:54.1 +42:19:46 2.3 7.47 24 PPM 045321 02:40:21.0 +49:33:37 6.5 2.39 30 PPM 045216 02:34:27.9 +46:41:36 8.2 0.65 27 PPM 045232 02:35:18.9 +47:02:34 9.3 0.29 28 17171_99NB38 02:35:15.3 +47:19:41 15.6 28 Positions are for J2000