Occultation event with (17171) 99NB38, event index number 1376
Regions able to see the event: Europe
Geocentric closest approach at 2025/10/16 21:46:06 UTC
J2000 position of star is 03:08:14.1 +48:51:49
Equinox of date position of star is 03:10:02.4 +48:57:40
Star is 92 degrees from the moon. Moon is 19% illuminated.
Stellar brightness G=15.1, apparent brightess of occulting body is G=15.7
Use an exposure time of 0.70 seconds with the standard RECON-QHY system.
SNR of 7.4 per integration for unocculted signal
Expected flux drop is 63% with SNR of 4.7 for the occulted depth (per occulted point)
Apparent velocity is 13.8 km/sec on the sky relative to the star, or, 15.6 arcsec/hr.
Position angle of asteroid motion is 103.2 degrees
The recommended exposure time corresponds to 9.7 km per image.
The 1-sigma error in the time of the event is 0.0 seconds.
The 1-sigma cross-track error in the shadow position is 28.8 km.
The sky-plane scale is 3185.4 km/arcsec.
Diameter estimates:
46.1 km assuming a 5% albedo, aximum of 3.3 sec for a central chord
18.8 km assuming a 30% albedo, maximum of 1.4 sec for a central chord
Cross-track diameter of 40.9 km used for deployment plan.
Star training set for 17171_99NB38, (2025/10/16 21:46UT) Object RA Dec mag sep mel Aldebaran 04:37:24.2 +16:33:32 0.8 36.95 82 Mirphak 03:26:10.7 +49:57:03 1.8 2.80 89 Iot Per 03:10:56.5 +49:42:35 4.0 0.76 92 PPM 045887 03:11:23.3 +48:43:16 8.1 0.33 92 PPM 045854 03:09:03.5 +49:08:13 9.6 0.24 92 PPM 045853 03:08:50.4 +48:54:29 10.2 0.20 92 17171_99NB38 03:10:02.4 +48:57:40 15.7 92 Positions are for equinox of date
Star training set for 17171_99NB38, (2025/10/16 21:46UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 36.95 82 Mirphak 03:24:19.4 +49:51:40 1.8 2.80 89 Iot Per 03:09:07.3 +49:36:46 4.0 0.76 92 PPM 045887 03:09:35.1 +48:37:28 8.1 0.33 92 PPM 045854 03:07:15.1 +49:02:21 9.6 0.24 92 PPM 045853 03:07:02.3 +48:48:36 10.2 0.20 92 17171_99NB38 03:08:14.1 +48:51:49 15.7 92 Positions are for J2000