Occultation event with (17171) 99NB38, event index number 1316
Regions able to see the event: Europe,Australia
Geocentric closest approach at 2025/09/27 20:16:36 UTC
J2000 position of star is 03:17:18.0 +48:01:47
Equinox of date position of star is 03:19:06.3 +48:07:21
Star is 154 degrees from the moon. Moon is 30% illuminated.
Stellar brightness G=16.4, apparent brightess of occulting body is G=15.9
Use an exposure time of 0.90 seconds with the standard RECON-QHY system.
SNR of 3.0 per integration for unocculted signal
Expected flux drop is 38% with SNR of 1.1 for the occulted depth (per occulted point)
Apparent velocity is 11.2 km/sec on the sky relative to the star, or, 12.2 arcsec/hr.
Position angle of asteroid motion is 139.1 degrees
The recommended exposure time corresponds to 10.1 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 22.0 km.
The sky-plane scale is 3308.0 km/arcsec.
Diameter estimates:
46.1 km assuming a 5% albedo, aximum of 4.1 sec for a central chord
18.8 km assuming a 30% albedo, maximum of 1.7 sec for a central chord
Cross-track diameter of 40.9 km used for deployment plan.
Star training set for 17171_99NB38, (2025/09/27 20:17UT) Object RA Dec mag sep mel Aldebaran 04:37:24.0 +16:33:32 0.8 35.40 169 Mirphak 03:26:10.5 +49:57:02 1.8 2.16 154 PPM 045922 03:14:14.1 +47:49:14 6.3 0.87 154 PPM 045994 03:18:40.3 +48:13:23 8.5 0.12 154 PPM 045995 03:18:50.2 +48:07:33 9.2 0.04 154 17171_99NB38 03:19:06.3 +48:07:21 15.9 154 Positions are for equinox of date
Star training set for 17171_99NB38, (2025/09/27 20:17UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 35.40 169 Mirphak 03:24:19.4 +49:51:40 1.8 2.16 154 PPM 045922 03:12:26.6 +47:43:31 6.3 0.87 154 PPM 045994 03:16:52.0 +48:07:47 8.5 0.12 154 PPM 045995 03:17:01.9 +48:01:58 9.2 0.04 154 17171_99NB38 03:17:18.0 +48:01:47 15.9 154 Positions are for J2000