Occultation event with (3540) Protesilaos, event index number 1645
Regions able to see the event: SMexico
Geocentric closest approach at 2025/12/06 09:16:06 UTC
J2000 position of star is 12:42:43.7 +08:21:53
Equinox of date position of star is 12:44:02.5 +08:13:23
Star is 91 degrees from the moon. Moon is 97% illuminated.
Stellar brightness G=16.5, apparent brightess of occulting body is G=14.7
Use an exposure time of 1.25 seconds with the standard RECON-QHY system.
SNR of 3.0 per integration for unocculted signal
Expected flux drop is 16% with SNR of 0.5 for the occulted depth (per occulted point)
Apparent velocity is 24.2 km/sec on the sky relative to the star, or, 24.0 arcsec/hr.
Position angle of asteroid motion is 112.6 degrees
The recommended exposure time corresponds to 30.2 km per image.
The 1-sigma error in the time of the event is 1.6 seconds.
The 1-sigma cross-track error in the shadow position is 15.3 km.
The sky-plane scale is 3627.6 km/arcsec.
Diameter estimates:
80.5 km assuming a 5% albedo, aximum of 3.3 sec for a central chord
32.9 km assuming a 30% albedo, maximum of 1.4 sec for a central chord
Cross-track diameter of 70.2 km used for deployment plan.
Star training set for 3540_Protesilaos, (2025/12/06 09:16UT) Object RA Dec mag sep mel Spica 13:26:33.8 -11:17:45 1.0 22.20 109 Vindemiatrix 13:03:28.1 +10:49:13 2.8 5.45 94 32 Vir 12:46:55.7 +07:31:55 5.2 0.99 92 PPM 159095 12:43:34.8 +07:54:02 8.4 0.34 91 3540_Protesila 12:44:02.5 +08:13:23 14.7 91 Positions are for equinox of date
Star training set for 3540_Protesilaos, (2025/12/06 09:16UT) Object RA Dec mag sep mel Spica 13:25:11.5 -11:09:41 1.0 22.20 109 Vindemiatrix 13:02:10.1 +10:57:33 2.8 5.45 94 32 Vir 12:45:36.9 +07:40:24 5.2 0.99 92 PPM 159095 12:42:16.0 +08:02:33 8.4 0.34 91 3540_Protesila 12:42:43.7 +08:21:53 14.7 91 Positions are for J2000