Occultation event with (3540) Protesilaos, event index number 3411
Regions able to see the event: Australia
Geocentric closest approach at 2026/03/12 18:00:26 UTC
J2000 position of star is 12:45:55.0 +07:37:32
Equinox of date position of star is 12:47:14.6 +07:28:58
Star is 90 degrees from the moon. Moon is 37% illuminated.
Stellar brightness G=15.8, apparent brightess of occulting body is G=13.8
Use an exposure time of 1.05 seconds with the standard RECON-QHY system.
SNR of 4.0 per integration for unocculted signal
Expected flux drop is 14% with SNR of 0.5 for the occulted depth (per occulted point)
Apparent velocity is 16.0 km/sec on the sky relative to the star, or, 20.8 arcsec/hr.
Position angle of asteroid motion is 100.2 degrees
The recommended exposure time corresponds to 16.8 km per image.
The 1-sigma error in the time of the event is 2.2 seconds.
The 1-sigma cross-track error in the shadow position is 23.8 km.
The sky-plane scale is 2773.9 km/arcsec.
Diameter estimates:
80.5 km assuming a 5% albedo, maximum of 5.0 sec for a central chord
32.9 km assuming a 30% albedo, maximum of 2.1 sec for a central chord
Cross-track diameter of 70.2 km used for deployment plan.
Star training set for 3540_Protesilaos, (2026/03/12 18:00UT) Object RA Dec mag sep mel Spica 13:26:34.6 -11:17:50 1.0 21.18 73 Vindemiatrix 13:03:28.9 +10:49:08 2.8 5.21 88 32 Vir 12:46:56.5 +07:31:50 5.2 0.09 90 PPM 159095 12:43:35.6 +07:53:57 8.4 1.00 91 32 Vir 12:46:56.5 +07:31:50 5.2 0.09 90 3540_Protesila 12:47:14.6 +07:28:58 13.8 90 Positions are for equinox of date
Star training set for 3540_Protesilaos, (2026/03/12 18:00UT) Object RA Dec mag sep mel Spica 13:25:11.5 -11:09:41 1.0 21.18 73 Vindemiatrix 13:02:10.1 +10:57:33 2.8 5.21 88 32 Vir 12:45:36.9 +07:40:24 5.2 0.09 90 PPM 159095 12:42:16.0 +08:02:33 8.4 1.00 91 32 Vir 12:45:36.9 +07:40:24 5.2 0.09 90 3540_Protesila 12:45:55.0 +07:37:32 13.8 90 Positions are for J2000