Occultation event with (3540) Protesilaos, event index number 3543
Regions able to see the event: SAmericaS
Geocentric closest approach at 2026/03/30 08:20:01 UTC
J2000 position of star is 12:35:29.7 +07:58:22
Equinox of date position of star is 12:36:49.7 +07:49:43
Star is 30 degrees from the moon. Moon is 92% illuminated.
Stellar brightness G=15.1, apparent brightess of occulting body is G=13.7
Use an exposure time of 1.00 seconds with the standard RECON-QHY system.
SNR of 7.6 per integration for unocculted signal
Expected flux drop is 23% with SNR of 1.7 for the occulted depth (per occulted point)
Apparent velocity is 17.5 km/sec on the sky relative to the star, or, 22.8 arcsec/hr.
Position angle of asteroid motion is 94.9 degrees
The recommended exposure time corresponds to 17.5 km per image.
The 1-sigma error in the time of the event is 1.8 seconds.
The 1-sigma cross-track error in the shadow position is 27.0 km.
The sky-plane scale is 2756.9 km/arcsec.
Diameter estimates:
80.5 km assuming a 5% albedo, maximum of 4.6 sec for a central chord
32.9 km assuming a 30% albedo, maximum of 1.9 sec for a central chord
Cross-track diameter of 70.2 km used for deployment plan.
Star training set for 3540_Protesilaos, (2026/03/30 08:20UT) Object RA Dec mag sep mel Spica 13:26:34.8 -11:17:51 1.0 22.78 47 Vindemiatrix 13:03:29.0 +10:49:07 2.8 7.22 36 PPM 158929 12:32:41.5 +07:27:35 6.0 1.09 29 PPM 158971 12:35:50.9 +07:35:24 7.8 0.34 30 PPM 159003 12:38:08.7 +07:47:20 9.2 0.33 30 PPM 158995 12:37:39.3 +07:45:23 10.4 0.22 30 3540_Protesila 12:36:49.7 +07:49:43 13.7 30 Positions are for equinox of date
Star training set for 3540_Protesilaos, (2026/03/30 08:20UT) Object RA Dec mag sep mel Spica 13:25:11.5 -11:09:41 1.0 22.78 47 Vindemiatrix 13:02:10.1 +10:57:33 2.8 7.22 36 PPM 158929 12:31:21.4 +07:36:16 6.0 1.09 29 PPM 158971 12:34:30.9 +07:44:03 7.8 0.34 30 PPM 159003 12:36:48.8 +07:55:59 9.2 0.33 30 PPM 158995 12:36:19.4 +07:54:02 10.4 0.22 30 3540_Protesila 12:35:29.7 +07:58:22 13.7 30 Positions are for J2000