Occultation event with (17171) 99NB38, event index number 4026
Regions able to see the event: UAE
Geocentric closest approach at 2026/08/17 00:15:07 UTC
J2000 position of star is 05:50:58.2 +43:41:42
Equinox of date position of star is 05:52:54.0 +43:42:00
Star is 110 degrees from the moon. Moon is 21% illuminated.
Stellar brightness G=16.1, apparent brightess of occulting body is G=16.5
Use an exposure time of 0.60 seconds with the standard RECON-QHY system.
SNR of 3.2 per integration for unocculted signal
Expected flux drop is 59% with SNR of 1.9 for the occulted depth (per occulted point)
Apparent velocity is 28.7 km/sec on the sky relative to the star, or, 24.6 arcsec/hr.
Position angle of asteroid motion is 78.9 degrees
The recommended exposure time corresponds to 17.2 km per image.
The 1-sigma error in the time of the event is 0.1 seconds.
The 1-sigma cross-track error in the shadow position is 29.2 km.
The sky-plane scale is 4201.9 km/arcsec.
Diameter estimates:
46.1 km assuming a 5% albedo, maximum of 1.6 sec for a central chord
18.8 km assuming a 30% albedo, maximum of 0.7 sec for a central chord
Cross-track diameter of 40.9 km used for deployment plan.
Star training set for 17171_99NB38, (2026/08/17 00:15UT) Object RA Dec mag sep mel Pollux 07:46:56.5 +27:57:35 1.1 27.74 86 34Bet Aur 06:01:29.0 +44:56:50 1.9 1.98 109 PPM 048445 05:49:09.2 +42:32:02 6.3 1.35 111 PPM 048491 05:52:40.7 +43:41:41 8.2 0.04 110 17171_99NB38 05:52:54.0 +43:42:00 16.5 110 Positions are for equinox of date
Star training set for 17171_99NB38, (2026/08/17 00:15UT) Object RA Dec mag sep mel Pollux 07:45:17.7 +28:01:33 1.1 27.74 86 34Bet Aur 05:59:31.6 +44:56:51 1.9 1.98 109 PPM 048445 05:47:14.7 +42:31:34 6.3 1.35 111 PPM 048491 05:50:44.9 +43:41:22 8.2 0.04 110 17171_99NB38 05:50:58.2 +43:41:42 16.5 110 Positions are for J2000