Occultation event with (4138) Kalchas, event index number 746
Regions able to see the event: SAmericaN,SAfrica
Geocentric closest approach at 2025/03/02 01:33:21 UTC
J2000 position of star is 10:05:28.5 +09:28:08
Equinox of date position of star is 10:06:48.6 +09:20:45
Star is 140 degrees from the moon. Moon is 6% illuminated.
Stellar brightness G=16.5, apparent brightess of occulting body is G=15.1
Use an exposure time of 1.15 seconds with the standard RECON-QHY system.
Expected flux drop is 79% with SNR of 3.0 per integration
Apparent velocity is 16.9 km/sec on the sky relative to the star, or, 19.2 arcsec/hr.
The recommended exposure time corresponds to 19.4 km per image.
The 1-sigma error in the time of the event is 2.7 seconds.
The 1-sigma cross-track error in the shadow position is 22.3 km.
The sky-plane scale is 3163.9 km/arcsec.
Diameter estimates:
55.2 km assuming a 5% albedo, aximum of 3.3 sec for a central chord
22.5 km assuming a 30% albedo, maximum of 1.3 sec for a central chord
Cross-track diameter of 55.2 km used for deployment plan.
Star training set for 4138_Kalchas, (2025/03/02 01:33UT) Object RA Dec mag sep mel Regulus 10:09:42.6 +11:50:36 1.3 2.60 140 31 Leo 10:09:14.3 +09:52:23 6.0 0.80 141 PPM 156458 10:04:53.4 +09:46:35 7.4 0.64 140 PPM 156493 10:06:40.2 +09:20:24 9.5 0.03 140 4138_Kalchas 10:06:48.6 +09:20:45 15.1 141 Positions are for equinox of date
Star training set for 4138_Kalchas, (2025/03/02 01:33UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 2.60 140 31 Leo 10:07:54.1 +09:59:49 6.0 0.80 141 PPM 156458 10:03:33.2 +09:53:56 7.4 0.64 140 PPM 156493 10:05:20.2 +09:27:47 9.5 0.03 140 4138_Kalchas 10:05:28.5 +09:28:08 15.1 140 Positions are for J2000