Occultation event with (11887) Echemmon, event index number 1244
Regions able to see the event: Europe
Geocentric closest approach at 2025/08/21 02:02:10 UTC
J2000 position of star is 03:16:51.9 +27:49:12
Equinox of date position of star is 03:18:24.5 +27:54:46
Star is 67 degrees from the moon. Moon is 5% illuminated.
Stellar brightness G=16.2, apparent brightess of occulting body is G=16.1
Use an exposure time of 0.75 seconds with the standard RECON-QHY system.
SNR of 3.1 per integration for unocculted signal
Expected flux drop is 47% with SNR of 1.5 for the occulted depth (per occulted point)
Apparent velocity is 10.1 km/sec on the sky relative to the star, or, 10.8 arcsec/hr.
Position angle of asteroid motion is 80.6 degrees
The recommended exposure time corresponds to 7.6 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 34.8 km.
The sky-plane scale is 3369.0 km/arcsec.
Diameter estimates:
40.7 km assuming a 5% albedo, aximum of 4.0 sec for a central chord
16.6 km assuming a 30% albedo, maximum of 1.7 sec for a central chord
Cross-track diameter of 31.2 km used for deployment plan.
Star training set for 11887_Echemmon, (2025/08/21 02:02UT) Object RA Dec mag sep mel Aldebaran 04:37:23.7 +16:33:31 0.8 21.47 53 44Zet Per 03:55:45.0 +31:57:27 2.8 9.04 58 56 Ari 03:13:46.3 +27:21:07 5.6 1.17 68 PPM 092390 03:21:10.1 +27:38:03 8.0 0.67 67 PPM 092368 03:19:37.9 +27:30:28 9.6 0.49 67 PPM 092356 03:18:50.6 +27:53:38 11.4 0.10 67 11887_Echemmon 03:18:24.5 +27:54:46 16.1 67 Positions are for equinox of date
Star training set for 11887_Echemmon, (2025/08/21 02:02UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 21.47 53 44Zet Per 03:54:07.9 +31:53:01 2.8 9.04 58 56 Ari 03:12:14.2 +27:15:25 5.6 1.17 68 PPM 092390 03:19:37.5 +27:32:33 8.0 0.67 67 PPM 092368 03:18:05.4 +27:24:56 9.6 0.49 67 PPM 092356 03:17:18.0 +27:48:04 11.4 0.10 67 11887_Echemmon 03:16:51.9 +27:49:12 16.1 67 Positions are for J2000