Occultation event with (1208) Troilus, event index number 4261
Regions able to see the event: US,RECON
Geocentric closest approach at 2026/09/18 10:19:04 UTC
J2000 position of star is 05:39:50.4 +39:47:09
Equinox of date position of star is 05:41:42.2 +39:47:54
Star is 167 degrees from the moon. Moon is 46% illuminated.
Stellar brightness G=12.3, apparent brightess of occulting body is G=14.7
Use an exposure time of 0.12 seconds with the standard RECON-QHY system.
SNR of 17.6 per integration for unocculted signal
Expected flux drop is 90% with SNR of 15.9 for the occulted depth (per occulted point)
Apparent velocity is 18.0 km/sec on the sky relative to the star, or, 17.3 arcsec/hr.
Position angle of asteroid motion is 35.9 degrees
The recommended exposure time corresponds to 2.2 km per image.
The 1-sigma error in the time of the event is 1.9 seconds.
The 1-sigma cross-track error in the shadow position is 4.2 km.
The sky-plane scale is 3738.9 km/arcsec.
Diameter estimates:
92.9 km assuming a 5% albedo, maximum of 5.2 sec for a central chord
37.9 km assuming a 30% albedo, maximum of 2.1 sec for a central chord
Cross-track diameter of 100.5 km used for deployment plan.
Star training set for 1208_Troilus, (2026/09/18 10:19UT) Object RA Dec mag sep mel Aldebaran 04:37:27.4 +16:33:39 0.8 27.11 165 34Bet Aur 06:01:29.4 +44:56:50 1.9 6.31 161 32Nu Aur 05:53:20.6 +39:09:12 4.0 2.34 167 PPM 070699 05:42:24.1 +39:50:46 8.0 0.14 167 1208_Troilus 05:41:42.2 +39:47:54 14.7 167 Positions are for equinox of date
This table contains the target star visibility for registered US 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 |
|---|---|---|---|---|---|---|---|---|---|---|
This table contains the target star visibility for registered RECON 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 1208_Troilus, (2026/09/18 10:19UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 27.11 165 34Bet Aur 05:59:31.6 +44:56:51 1.9 6.31 161 32Nu Aur 05:51:29.4 +39:08:55 4.0 2.34 167 PPM 070699 05:40:32.2 +39:50:03 8.0 0.14 167 1208_Troilus 05:39:50.4 +39:47:09 14.7 167 Positions are for J2000