Occultation event with (11887) Echemmon, event index number 4446
Regions able to see the event: SAmericaN
Geocentric closest approach at 2026/10/21 07:15:05 UTC
J2000 position of star is 05:50:05.6 +15:56:38
Equinox of date position of star is 05:51:38.3 +15:56:59
Star is 120 degrees from the moon. Moon is 75% illuminated.
Stellar brightness G=16.8, apparent brightess of occulting body is G=16.1
Use an exposure time of 1.50 seconds with the standard RECON-QHY system.
SNR of 3.0 per integration for unocculted signal
Expected flux drop is 34% with SNR of 1.0 for the occulted depth (per occulted point)
Apparent velocity is 9.0 km/sec on the sky relative to the star, or, 9.8 arcsec/hr.
Position angle of asteroid motion is 21.5 degrees
The recommended exposure time corresponds to 13.4 km per image.
The 1-sigma error in the time of the event is 3.1 seconds.
The 1-sigma cross-track error in the shadow position is 25.3 km.
The sky-plane scale is 3275.3 km/arcsec.
Diameter estimates:
40.7 km assuming a 5% albedo, maximum of 4.6 sec for a central chord
16.6 km assuming a 30% albedo, maximum of 1.9 sec for a central chord
Cross-track diameter of 31.2 km used for deployment plan.
Star training set for 11887_Echemmon, (2026/10/21 07:15UT) Object RA Dec mag sep mel Betelgeuse 05:56:37.4 +07:24:35 0.4 8.63 120 Bellatrix 05:26:34.2 +06:22:18 1.6 11.38 113 131 Tau 05:48:44.8 +14:29:46 5.7 1.61 119 PPM 121449 05:51:35.0 +16:01:09 8.3 0.07 120 11887_Echemmon 05:51:38.3 +15:56:59 16.1 120 Positions are for equinox of date
Star training set for 11887_Echemmon, (2026/10/21 07:15UT) Object RA Dec mag sep mel Betelgeuse 05:55:10.3 +07:24:26 0.4 8.63 120 Bellatrix 05:25:07.8 +06:20:58 1.6 11.38 113 131 Tau 05:47:13.1 +14:29:18 5.7 1.61 119 PPM 121449 05:50:02.3 +16:00:47 8.3 0.07 120 11887_Echemmon 05:50:05.6 +15:56:38 16.1 120 Positions are for J2000