Occultation event with (17171) 99NB38, event index number 1301
Regions able to see the event: Europe,UAE
Geocentric closest approach at 2025/09/21 22:35:04 UTC
J2000 position of star is 03:18:52.1 +47:38:22
Equinox of date position of star is 03:20:40.1 +47:43:53
Star is 117 degrees from the moon. Moon is 0% illuminated.
Stellar brightness G=14.3, apparent brightess of occulting body is G=15.9
Use an exposure time of 0.40 seconds with the standard RECON-QHY system.
SNR of 10.0 per integration for unocculted signal
Expected flux drop is 82% with SNR of 8.2 for the occulted depth (per occulted point)
Apparent velocity is 11.0 km/sec on the sky relative to the star, or, 11.8 arcsec/hr.
Position angle of asteroid motion is 153.1 degrees
The recommended exposure time corresponds to 4.4 km per image.
The 1-sigma error in the time of the event is 2.0 seconds.
The 1-sigma cross-track error in the shadow position is 17.4 km.
The sky-plane scale is 3354.6 km/arcsec.
Diameter estimates:
46.1 km assuming a 5% albedo, aximum of 4.2 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, (2025/09/21 22:35UT) Object RA Dec mag sep mel Aldebaran 04:37:24.0 +16:33:32 0.8 34.93 110 Mirphak 03:26:10.4 +49:57:02 1.8 2.40 115 PPM 045922 03:14:14.0 +47:49:14 6.3 1.08 118 PPM 046036 03:21:29.7 +47:57:45 8.2 0.27 117 PPM 046008 03:19:41.6 +47:43:59 8.7 0.16 117 17171_99NB38 03:20:40.1 +47:43:53 15.9 116 Positions are for equinox of date
Star training set for 17171_99NB38, (2025/09/21 22:35UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 34.93 110 Mirphak 03:24:19.4 +49:51:40 1.8 2.40 115 PPM 045922 03:12:26.6 +47:43:31 6.3 1.08 118 PPM 046036 03:19:41.3 +47:52:15 8.2 0.27 117 PPM 046008 03:17:53.7 +47:38:26 8.7 0.16 117 17171_99NB38 03:18:52.1 +47:38:22 15.9 117 Positions are for J2000