Occultation event with (1872) Helenos, event index number 4379
Regions able to see the event: Australia
Geocentric closest approach at 2026/10/10 16:49:21 UTC
J2000 position of star is 05:07:02.4 +08:47:49
Equinox of date position of star is 05:08:30.1 +08:49:51
Star is 119 degrees from the moon. Moon is 0% illuminated.
Stellar brightness G=15.0, apparent brightess of occulting body is G=16.3
Use an exposure time of 0.85 seconds with the standard RECON-QHY system.
SNR of 9.9 per integration for unocculted signal
Expected flux drop is 78% with SNR of 7.7 for the occulted depth (per occulted point)
Apparent velocity is 8.0 km/sec on the sky relative to the star, or, 8.2 arcsec/hr.
Position angle of asteroid motion is 18.8 degrees
The recommended exposure time corresponds to 6.8 km per image.
The 1-sigma error in the time of the event is 4.2 seconds.
The 1-sigma cross-track error in the shadow position is 11.5 km.
The sky-plane scale is 3546.7 km/arcsec.
Diameter estimates:
42.1 km assuming a 5% albedo, maximum of 5.2 sec for a central chord
17.2 km assuming a 30% albedo, maximum of 2.1 sec for a central chord
Cross-track diameter of 34.0 km used for deployment plan.
Star training set for 1872_Helenos, (2026/10/10 16:49UT) Object RA Dec mag sep mel Aldebaran 04:37:27.6 +16:33:39 0.8 10.82 127 Bellatrix 05:26:34.1 +06:22:18 1.6 5.11 114 14 Ori 05:09:20.5 +08:31:53 5.7 0.36 119 PPM 148418 05:06:40.8 +08:58:38 7.2 0.47 120 PPM 148502 05:09:45.7 +08:50:01 8.9 0.31 119 PPM 148481 05:09:14.6 +08:45:55 10.9 0.19 119 1872_Helenos 05:08:30.1 +08:49:51 16.3 119 Positions are for equinox of date
Star training set for 1872_Helenos, (2026/10/10 16:49UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 10.82 127 Bellatrix 05:25:07.8 +06:20:58 1.6 5.11 114 14 Ori 05:07:52.9 +08:29:53 5.7 0.36 119 PPM 148418 05:05:13.0 +08:56:32 7.2 0.47 120 PPM 148502 05:08:18.0 +08:48:03 8.9 0.31 119 PPM 148481 05:07:46.9 +08:43:56 10.9 0.19 119 1872_Helenos 05:07:02.4 +08:47:49 16.3 119 Positions are for J2000