Occultation event with (4138) Kalchas, event index number 706
Regions able to see the event: Australia
Geocentric closest approach at 2025/02/24 15:54:57 UTC
J2000 position of star is 10:08:07.3 +09:12:27
Equinox of date position of star is 10:09:27.1 +09:05:01
Star is 141 degrees from the moon. Moon is 14% illuminated.
Stellar brightness G=14.3, apparent brightess of occulting body is G=14.9
Use an exposure time of 0.40 seconds with the standard RECON-QHY system.
Expected flux drop is 35% with SNR of 9.7 per integration
Apparent velocity is 17.3 km/sec on the sky relative to the star, or, 19.8 arcsec/hr.
The recommended exposure time corresponds to 6.9 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 20.4 km.
The sky-plane scale is 3155.0 km/arcsec.
Diameter estimates:
55.2 km assuming a 5% albedo, aximum of 3.2 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, (2025/02/24 15:55UT) Object RA Dec mag sep mel Regulus 10:09:42.5 +11:50:36 1.3 2.76 142 31 Leo 10:09:14.2 +09:52:24 6.0 0.79 141 PPM 156568 10:10:51.4 +09:28:08 8.2 0.52 141 PPM 156527 10:08:27.6 +08:38:43 9.1 0.50 141 PPM 156537 10:09:11.2 +09:04:56 11.6 0.07 141 4138_Kalchas 10:09:27.1 +09:05:01 14.9 141 Positions are for equinox of date
Star training set for 4138_Kalchas, (2025/02/24 15:55UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 2.76 142 31 Leo 10:07:54.1 +09:59:49 6.0 0.79 141 PPM 156568 10:09:31.4 +09:35:35 8.2 0.52 141 PPM 156527 10:07:07.8 +08:46:07 9.1 0.50 141 PPM 156537 10:07:51.4 +09:12:22 11.6 0.07 141 4138_Kalchas 10:08:07.3 +09:12:27 14.9 141 Positions are for J2000