Occultation event with (11887) Echemmon, event index number 4222
Regions able to see the event: SMexico
Geocentric closest approach at 2026/09/11 09:05:24 UTC
J2000 position of star is 05:43:10.7 +18:09:16
Equinox of date position of star is 05:44:44.5 +18:09:53
Star is 85 degrees from the moon. Moon is 0% illuminated.
Stellar brightness G=16.2, apparent brightess of occulting body is G=16.4
Use an exposure time of 0.65 seconds with the standard RECON-QHY system.
SNR of 3.0 per integration for unocculted signal
Expected flux drop is 55% with SNR of 1.7 for the occulted depth (per occulted point)
Apparent velocity is 17.2 km/sec on the sky relative to the star, or, 16.8 arcsec/hr.
Position angle of asteroid motion is 115.2 degrees
The recommended exposure time corresponds to 11.2 km per image.
The 1-sigma error in the time of the event is 1.6 seconds.
The 1-sigma cross-track error in the shadow position is 25.7 km.
The sky-plane scale is 3691.6 km/arcsec.
Diameter estimates:
40.7 km assuming a 5% albedo, maximum of 2.4 sec for a central chord
16.6 km assuming a 30% albedo, maximum of 1.0 sec for a central chord
Cross-track diameter of 31.2 km used for deployment plan.
Star training set for 11887_Echemmon, (2026/09/11 09:05UT) Object RA Dec mag sep mel Betelgeuse 05:56:37.1 +07:24:35 0.4 11.14 83 Alnath 05:27:58.9 +28:37:39 1.6 11.14 89 126 Tau 05:42:50.3 +16:32:43 4.6 1.68 86 PPM 121313 05:44:41.3 +18:31:49 8.3 0.37 86 PPM 121318 05:45:01.8 +18:05:53 9.5 0.10 85 11887_Echemmon 05:44:44.5 +18:09:53 16.4 85 Positions are for equinox of date
Star training set for 11887_Echemmon, (2026/09/11 09:05UT) Object RA Dec mag sep mel Betelgeuse 05:55:10.3 +07:24:26 0.4 11.14 83 Alnath 05:26:17.6 +28:36:22 1.6 11.14 89 126 Tau 05:41:17.7 +16:32:01 4.6 1.68 86 PPM 121313 05:43:07.3 +18:31:11 8.3 0.37 86 PPM 121318 05:43:28.1 +18:05:16 9.5 0.10 85 11887_Echemmon 05:43:10.7 +18:09:16 16.4 85 Positions are for J2000