Occultation event with (1872) Helenos, event index number 4295
Regions able to see the event: SAmericaN
Geocentric closest approach at 2026/09/24 04:30:04 UTC
J2000 position of star is 05:06:30.1 +09:37:01
Equinox of date position of star is 05:07:58.2 +09:39:03
Star is 105 degrees from the moon. Moon is 93% illuminated.
Stellar brightness G=15.8, apparent brightess of occulting body is G=16.5
Use an exposure time of 0.95 seconds with the standard RECON-QHY system.
SNR of 5.3 per integration for unocculted signal
Expected flux drop is 64% with SNR of 3.4 for the occulted depth (per occulted point)
Apparent velocity is 8.9 km/sec on the sky relative to the star, or, 8.6 arcsec/hr.
Position angle of asteroid motion is 144.8 degrees
The recommended exposure time corresponds to 8.5 km per image.
The 1-sigma error in the time of the event is 3.2 seconds.
The 1-sigma cross-track error in the shadow position is 19.9 km.
The sky-plane scale is 3711.5 km/arcsec.
Diameter estimates:
42.1 km assuming a 5% albedo, maximum of 4.7 sec for a central chord
17.2 km assuming a 30% albedo, maximum of 1.9 sec for a central chord
Cross-track diameter of 34.0 km used for deployment plan.
Star training set for 1872_Helenos, (2026/09/24 04:30UT) Object RA Dec mag sep mel Aldebaran 04:37:27.5 +16:33:39 0.8 10.14 99 Bellatrix 05:26:34.0 +06:22:18 1.6 5.65 109 16 Ori 05:10:48.0 +09:51:42 5.4 0.73 106 PPM 148418 05:06:40.7 +08:58:37 7.2 0.75 105 PPM 148493 05:09:30.8 +09:24:29 8.8 0.45 106 1872_Helenos 05:07:58.2 +09:39:03 16.5 106 Positions are for equinox of date
Star training set for 1872_Helenos, (2026/09/24 04:30UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 10.14 99 Bellatrix 05:25:07.8 +06:20:58 1.6 5.65 109 16 Ori 05:09:19.7 +09:49:46 5.4 0.73 106 PPM 148418 05:05:13.0 +08:56:32 7.2 0.75 105 PPM 148493 05:08:02.8 +09:22:31 8.8 0.45 106 1872_Helenos 05:06:30.1 +09:37:01 16.5 105 Positions are for J2000