Occultation event with (1872) Helenos, event index number 4148
Regions able to see the event: SAmericaN
Geocentric closest approach at 2026/09/01 09:18:59 UTC
J2000 position of star is 05:00:25.5 +10:34:05
Equinox of date position of star is 05:01:54.0 +10:36:21
Star is 47 degrees from the moon. Moon is 81% illuminated.
Stellar brightness G=16.2, apparent brightess of occulting body is G=16.6
Use an exposure time of 0.70 seconds with the standard RECON-QHY system.
SNR of 3.1 per integration for unocculted signal
Expected flux drop is 59% with SNR of 1.8 for the occulted depth (per occulted point)
Apparent velocity is 16.9 km/sec on the sky relative to the star, or, 15.4 arcsec/hr.
Position angle of asteroid motion is 110.3 degrees
The recommended exposure time corresponds to 11.8 km per image.
The 1-sigma error in the time of the event is 0.7 seconds.
The 1-sigma cross-track error in the shadow position is 34.1 km.
The sky-plane scale is 3957.9 km/arcsec.
Diameter estimates:
42.1 km assuming a 5% albedo, maximum of 2.5 sec for a central chord
17.2 km assuming a 30% albedo, maximum of 1.0 sec for a central chord
Cross-track diameter of 34.0 km used for deployment plan.
Star training set for 1872_Helenos, (2026/09/01 09:19UT) Object RA Dec mag sep mel Aldebaran 04:37:27.2 +16:33:39 0.8 8.41 40 Bellatrix 05:26:33.8 +06:22:18 1.6 7.42 54 6 Ori 04:56:15.8 +11:28:03 5.2 1.63 46 PPM 120481 05:01:29.9 +10:25:43 8.1 0.20 47 PPM 120480 05:01:28.8 +10:32:22 11.7 0.12 47 1872_Helenos 05:01:54.0 +10:36:21 16.6 47 Positions are for equinox of date
Star training set for 1872_Helenos, (2026/09/01 09:19UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 8.41 40 Bellatrix 05:25:07.8 +06:20:58 1.6 7.42 54 6 Ori 04:54:46.9 +11:25:35 5.2 1.63 46 PPM 120481 05:00:01.6 +10:23:26 8.1 0.20 47 PPM 120480 05:00:00.4 +10:30:06 11.7 0.12 47 1872_Helenos 05:00:25.5 +10:34:05 16.6 47 Positions are for J2000