Occultation event with (4138) Kalchas, event index number 3805
Regions able to see the event: SAmericaS
Geocentric closest approach at 2026/06/23 23:32:02 UTC
J2000 position of star is 11:53:06.6 +00:00:24
Equinox of date position of star is 11:54:28.0 -00:08:27
Star is 28 degrees from the moon. Moon is 70% illuminated.
Stellar brightness G=16.3, apparent brightess of occulting body is G=16.0
Use an exposure time of 0.80 seconds with the standard RECON-QHY system.
SNR of 3.1 per integration for unocculted signal
Expected flux drop is 42% with SNR of 1.3 for the occulted depth (per occulted point)
Apparent velocity is 14.2 km/sec on the sky relative to the star, or, 13.1 arcsec/hr.
Position angle of asteroid motion is 110.4 degrees
The recommended exposure time corresponds to 11.3 km per image.
The 1-sigma error in the time of the event is 1.7 seconds.
The 1-sigma cross-track error in the shadow position is 26.8 km.
The sky-plane scale is 3895.7 km/arcsec.
Diameter estimates:
56.2 km assuming a 5% albedo, maximum of 4.0 sec for a central chord
23.0 km assuming a 30% albedo, maximum of 1.6 sec for a central chord
Cross-track diameter of 46.5 km used for deployment plan.
Star training set for 4138_Kalchas, (2026/06/23 23:32UT) Object RA Dec mag sep mel Spica 13:26:35.5 -11:17:55 1.0 25.45 3 Denebola 11:50:24.5 +14:25:26 2.1 14.60 38 5Bet Vir 11:52:04.4 +01:36:56 3.6 1.86 30 PPM 158301 11:55:11.6 +00:24:18 6.6 0.58 28 PPM 178627 11:55:38.8 -00:13:01 10.0 0.30 28 PPM 158294 11:54:23.1 -00:05:46 11.5 0.05 28 4138_Kalchas 11:54:28.0 -00:08:27 16.0 28 Positions are for equinox of date
Star training set for 4138_Kalchas, (2026/06/23 23:32UT) Object RA Dec mag sep mel Spica 13:25:11.5 -11:09:41 1.0 25.45 3 Denebola 11:49:02.7 +14:34:16 2.1 14.60 38 5Bet Vir 11:50:43.0 +01:45:46 3.6 1.86 30 PPM 158301 11:53:50.2 +00:33:08 6.6 0.58 28 PPM 178627 11:54:17.4 -00:04:10 10.0 0.30 28 PPM 158294 11:53:01.7 +00:03:05 11.5 0.05 28 4138_Kalchas 11:53:06.6 +00:00:24 16.0 28 Positions are for J2000