Occultation event with (17171) 99NB38, event index number 3165
Regions able to see the event: Europe
Geocentric closest approach at 2026/01/22 22:18:44 UTC
J2000 position of star is 02:28:36.0 +42:50:36
Equinox of date position of star is 02:30:15.8 +42:57:31
Star is 61 degrees from the moon. Moon is 17% illuminated.
Stellar brightness G=13.7, apparent brightess of occulting body is G=16.1
Use an exposure time of 0.20 seconds with the standard RECON-QHY system.
SNR of 9.3 per integration for unocculted signal
Expected flux drop is 90% with SNR of 8.3 for the occulted depth (per occulted point)
Apparent velocity is 13.7 km/sec on the sky relative to the star, or, 13.9 arcsec/hr.
Position angle of asteroid motion is 141.8 degrees
The recommended exposure time corresponds to 2.7 km per image.
The 1-sigma error in the time of the event is 1.0 seconds.
The 1-sigma cross-track error in the shadow position is 23.8 km.
The sky-plane scale is 3528.9 km/arcsec.
Diameter estimates:
46.1 km assuming a 5% albedo, maximum of 3.4 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, (2026/01/22 22:19UT) Object RA Dec mag sep mel Aldebaran 04:37:25.2 +16:33:34 0.8 37.77 78 57Gam1And 02:05:30.7 +42:27:13 2.3 4.57 57 PPM 045035 02:24:28.3 +41:30:47 6.1 1.80 59 PPM 045165 02:33:06.8 +42:40:38 7.6 0.59 61 PPM 045116 02:30:04.0 +42:55:04 8.8 0.05 61 17171_99NB38 02:30:15.8 +42:57:31 16.1 61 Positions are for equinox of date
Star training set for 17171_99NB38, (2026/01/22 22:19UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 37.77 78 57Gam1And 02:03:54.1 +42:19:46 2.3 4.57 57 PPM 045035 02:22:50.1 +41:23:44 6.1 1.80 59 PPM 045165 02:31:26.9 +42:33:47 7.6 0.59 61 PPM 045116 02:28:24.2 +42:48:09 8.8 0.05 61 17171_99NB38 02:28:36.0 +42:50:36 16.1 61 Positions are for J2000