Occultation event with (17171) 99NB38, event index number 1348
Regions able to see the event: Europe
Geocentric closest approach at 2025/10/08 17:48:04 UTC
J2000 position of star is 03:12:48.7 +48:35:43
Equinox of date position of star is 03:14:37.2 +48:41:26
Star is 33 degrees from the moon. Moon is 96% illuminated.
Stellar brightness G=15.4, apparent brightess of occulting body is G=15.8
Use an exposure time of 0.80 seconds with the standard RECON-QHY system.
SNR of 6.6 per integration for unocculted signal
Expected flux drop is 59% with SNR of 3.9 for the occulted depth (per occulted point)
Apparent velocity is 12.5 km/sec on the sky relative to the star, or, 13.9 arcsec/hr.
Position angle of asteroid motion is 116.7 degrees
The recommended exposure time corresponds to 10.0 km per image.
The 1-sigma error in the time of the event is 0.5 seconds.
The 1-sigma cross-track error in the shadow position is 27.2 km.
The sky-plane scale is 3232.1 km/arcsec.
Diameter estimates:
46.1 km assuming a 5% albedo, aximum of 3.7 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, (2025/10/08 17:48UT) Object RA Dec mag sep mel Aldebaran 04:37:24.1 +16:33:32 0.8 36.29 33 Mirphak 03:26:10.6 +49:57:03 1.8 2.27 35 PPM 045922 03:14:14.2 +47:49:15 6.3 0.87 32 PPM 045963 03:16:44.2 +48:47:24 8.0 0.36 33 17171_99NB38 03:14:37.2 +48:41:26 15.8 33 Positions are for equinox of date
Star training set for 17171_99NB38, (2025/10/08 17:48UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 36.29 33 Mirphak 03:24:19.4 +49:51:40 1.8 2.27 35 PPM 045922 03:12:26.6 +47:43:31 6.3 0.87 32 PPM 045963 03:14:55.3 +48:41:45 8.0 0.36 33 17171_99NB38 03:12:48.7 +48:35:43 15.8 33 Positions are for J2000