Occultation event with (11887) Echemmon, event index number 4209
Regions able to see the event: Australia
Geocentric closest approach at 2026/09/09 20:46:28 UTC
J2000 position of star is 05:42:31.2 +18:13:34
Equinox of date position of star is 05:44:05.0 +18:14:13
Star is 65 degrees from the moon. Moon is 2% illuminated.
Stellar brightness G=14.5, apparent brightess of occulting body is G=16.4
Use an exposure time of 0.40 seconds with the standard RECON-QHY system.
SNR of 8.4 per integration for unocculted signal
Expected flux drop is 85% with SNR of 7.1 for the occulted depth (per occulted point)
Apparent velocity is 17.8 km/sec on the sky relative to the star, or, 17.3 arcsec/hr.
Position angle of asteroid motion is 114.0 degrees
The recommended exposure time corresponds to 7.1 km per image.
The 1-sigma error in the time of the event is 1.5 seconds.
The 1-sigma cross-track error in the shadow position is 26.1 km.
The sky-plane scale is 3707.9 km/arcsec.
Diameter estimates:
40.7 km assuming a 5% albedo, maximum of 2.3 sec for a central chord
16.6 km assuming a 30% albedo, maximum of 0.9 sec for a central chord
Cross-track diameter of 31.2 km used for deployment plan.
Star training set for 11887_Echemmon, (2026/09/09 20:46UT) Object RA Dec mag sep mel Betelgeuse 05:56:37.1 +07:24:35 0.4 11.25 63 Alnath 05:27:58.9 +28:37:39 1.6 11.02 68 126 Tau 05:42:50.3 +16:32:43 4.6 1.72 65 PPM 121313 05:44:41.3 +18:31:48 8.3 0.33 65 PPM 121295 05:43:57.5 +18:05:26 9.5 0.15 65 11887_Echemmon 05:44:05.0 +18:14:13 16.4 65 Positions are for equinox of date
Star training set for 11887_Echemmon, (2026/09/09 20:46UT) Object RA Dec mag sep mel Betelgeuse 05:55:10.3 +07:24:26 0.4 11.25 63 Alnath 05:26:17.6 +28:36:22 1.6 11.02 68 126 Tau 05:41:17.7 +16:32:01 4.6 1.72 65 PPM 121313 05:43:07.3 +18:31:11 8.3 0.33 65 PPM 121295 05:42:23.8 +18:04:47 9.5 0.15 65 11887_Echemmon 05:42:31.2 +18:13:34 16.4 65 Positions are for J2000