Occultation event with (1872) Helenos, event index number 1508
Regions able to see the event: Europe
Geocentric closest approach at 2025/11/13 20:11:34 UTC
J2000 position of star is 02:39:25.5 +05:14:20
Equinox of date position of star is 02:40:47.1 +05:20:57
Star is 121 degrees from the moon. Moon is 34% illuminated.
Stellar brightness G=13.8, apparent brightess of occulting body is G=15.7
Use an exposure time of 0.20 seconds with the standard RECON-QHY system.
SNR of 8.9 per integration for unocculted signal
Expected flux drop is 86% with SNR of 7.6 for the occulted depth (per occulted point)
Apparent velocity is 16.9 km/sec on the sky relative to the star, or, 19.1 arcsec/hr.
Position angle of asteroid motion is 66.3 degrees
The recommended exposure time corresponds to 3.4 km per image.
The 1-sigma error in the time of the event is 0.9 seconds.
The 1-sigma cross-track error in the shadow position is 28.4 km.
The sky-plane scale is 3177.7 km/arcsec.
Diameter estimates:
42.1 km assuming a 5% albedo, aximum 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, (2025/11/13 20:12UT) Object RA Dec mag sep mel Aldebaran 04:37:24.5 +16:33:33 0.8 30.68 91 Menkar 03:03:38.1 +04:11:23 2.5 5.81 116 78Nu Cet 02:37:14.1 +05:42:17 4.9 0.95 122 PPM 145808 02:42:18.2 +04:58:49 7.4 0.53 121 PPM 145794 02:41:23.7 +05:13:11 9.4 0.20 121 1872_Helenos 02:40:47.1 +05:20:57 15.7 121 Positions are for equinox of date
Star training set for 1872_Helenos, (2025/11/13 20:12UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 30.68 91 Menkar 03:02:16.8 +04:05:21 2.5 5.81 116 78Nu Cet 02:35:52.4 +05:35:35 4.9 0.95 122 PPM 145808 02:40:56.7 +04:52:14 7.4 0.53 121 PPM 145794 02:40:02.1 +05:06:35 9.4 0.20 121 1872_Helenos 02:39:25.5 +05:14:20 15.7 121 Positions are for J2000