Occultation event with (3540) Protesilaos, event index number 3635
Regions able to see the event: SAmericaS
Geocentric closest approach at 2026/04/15 00:46:07 UTC
J2000 position of star is 12:26:12.4 +08:02:33
Equinox of date position of star is 12:27:32.7 +07:53:50
Star is 165 degrees from the moon. Moon is 8% illuminated.
Stellar brightness G=15.2, apparent brightess of occulting body is G=13.9
Use an exposure time of 1.05 seconds with the standard RECON-QHY system.
SNR of 6.9 per integration for unocculted signal
Expected flux drop is 23% with SNR of 1.6 for the occulted depth (per occulted point)
Apparent velocity is 16.1 km/sec on the sky relative to the star, or, 20.7 arcsec/hr.
Position angle of asteroid motion is 87.9 degrees
The recommended exposure time corresponds to 16.9 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 30.9 km.
The sky-plane scale is 2798.7 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 2.0 sec for a central chord
Cross-track diameter of 70.2 km used for deployment plan.
Star training set for 3540_Protesilaos, (2026/04/15 00:46UT) Object RA Dec mag sep mel Spica 13:26:34.9 -11:17:52 1.0 24.17 148 Vindemiatrix 13:03:29.1 +10:49:06 2.8 9.33 155 PPM 158929 12:32:41.6 +07:27:34 6.0 1.35 164 PPM 158863 12:29:02.3 +08:27:54 7.4 0.68 164 PPM 158840 12:27:53.7 +07:44:54 9.0 0.17 165 3540_Protesila 12:27:32.7 +07:53:50 13.9 164 Positions are for equinox of date
This table contains the target star visibility for registered SAmericaS sites that are relevant for this occultation. This list has been filtered to only those sites that can see the field and are within range of the shadow given the uncertainties. The observing time range has been calculated to cover the time of the event at each site with allowances for the event timing uncertainty plus time for obtaining a pre and post event baseline lightcurve. This set of stations has a 0.0 % chance of getting at least one chord. There is a 0.0% chance of 2 or more chords assuming clear weather for all.
| Site Name | Site mid-time (UT) |
Sun alt (deg) |
Sky | Moon | Star alt (deg) |
Star az (deg) |
Target | Observing Time | Xtrack (km) |
Prob |
|---|---|---|---|---|---|---|---|---|---|---|
Star training set for 3540_Protesilaos, (2026/04/15 00:46UT) Object RA Dec mag sep mel Spica 13:25:11.5 -11:09:41 1.0 24.17 148 Vindemiatrix 13:02:10.1 +10:57:33 2.8 9.33 155 PPM 158929 12:31:21.4 +07:36:16 6.0 1.35 164 PPM 158863 12:27:42.1 +08:36:37 7.4 0.68 164 PPM 158840 12:26:33.4 +07:53:37 9.0 0.17 165 3540_Protesila 12:26:12.4 +08:02:33 13.9 165 Positions are for J2000