Occultation event with (11887) Echemmon, event index number 4166
Regions able to see the event: SAmericaN,SAmericaS
Geocentric closest approach at 2026/09/03 08:55:42 UTC
J2000 position of star is 05:39:24.4 +18:31:14
Equinox of date position of star is 05:40:58.3 +18:32:00
Star is 29 degrees from the moon. Moon is 61% illuminated.
Stellar brightness G=13.9, apparent brightess of occulting body is G=16.5
Use an exposure time of 0.25 seconds with the standard RECON-QHY system.
SNR of 9.6 per integration for unocculted signal
Expected flux drop is 91% with SNR of 8.7 for the occulted depth (per occulted point)
Apparent velocity is 20.4 km/sec on the sky relative to the star, or, 19.4 arcsec/hr.
Position angle of asteroid motion is 109.7 degrees
The recommended exposure time corresponds to 5.1 km per image.
The 1-sigma error in the time of the event is 1.2 seconds.
The 1-sigma cross-track error in the shadow position is 27.6 km.
The sky-plane scale is 3776.8 km/arcsec.
Diameter estimates:
40.7 km assuming a 5% albedo, maximum of 2.0 sec for a central chord
16.6 km assuming a 30% albedo, maximum of 0.8 sec for a central chord
Cross-track diameter of 31.2 km used for deployment plan.
Star training set for 11887_Echemmon, (2026/09/03 08:56UT) Object RA Dec mag sep mel Betelgeuse 05:56:37.0 +07:24:35 0.4 11.76 37 Alnath 05:27:58.8 +28:37:39 1.6 10.52 24 120 Tau 05:35:05.5 +18:33:25 5.4 1.39 27 PPM 121262 05:42:42.8 +18:38:09 8.2 0.43 29 PPM 121215 05:40:23.2 +18:40:27 9.1 0.20 28 11887_Echemmon 05:40:58.3 +18:32:00 16.5 29 Positions are for equinox of date
Star training set for 11887_Echemmon, (2026/09/03 08:56UT) Object RA Dec mag sep mel Betelgeuse 05:55:10.3 +07:24:26 0.4 11.76 37 Alnath 05:26:17.6 +28:36:22 1.6 10.52 24 120 Tau 05:33:31.6 +18:32:25 5.4 1.39 27 PPM 121262 05:41:08.8 +18:37:27 8.2 0.43 29 PPM 121215 05:38:49.2 +18:39:40 9.1 0.20 28 11887_Echemmon 05:39:24.4 +18:31:14 16.5 29 Positions are for J2000