Occultation event with (20729) 99XS143, event index number 3786
Regions able to see the event: Japan
Geocentric closest approach at 2026/06/11 12:06:35 UTC
J2000 position of star is 10:57:05.2 -13:40:55
Equinox of date position of star is 10:58:24.1 -13:49:25
Star is 139 degrees from the moon. Moon is 19% illuminated.
Stellar brightness G=16.4, apparent brightess of occulting body is G=16.3
Use an exposure time of 1.00 seconds with the standard RECON-QHY system.
SNR of 3.4 per integration for unocculted signal
Expected flux drop is 48% with SNR of 1.6 for the occulted depth (per occulted point)
Apparent velocity is 12.7 km/sec on the sky relative to the star, or, 11.7 arcsec/hr.
Position angle of asteroid motion is 85.4 degrees
The recommended exposure time corresponds to 12.7 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 31.4 km.
The sky-plane scale is 3899.9 km/arcsec.
Diameter estimates:
48.3 km assuming a 5% albedo, maximum of 3.8 sec for a central chord
19.7 km assuming a 30% albedo, maximum of 1.6 sec for a central chord
Cross-track diameter of 51.0 km used for deployment plan.
Star training set for 20729_99XS143, (2026/06/11 12:07UT) Object RA Dec mag sep mel Regulus 10:09:46.7 +11:50:13 1.3 28.35 120 4Gam Crv 12:17:10.2 -17:41:19 2.6 19.33 159 PPM 223779 11:01:30.7 -14:13:33 5.8 0.85 140 PPM 223756 11:00:45.8 -14:18:50 8.4 0.75 140 PPM 223724 10:59:21.2 -13:45:41 9.4 0.24 140 20729_99XS143 10:58:24.1 -13:49:25 16.3 140 Positions are for equinox of date
This table contains the target star visibility for registered Japan 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 30.2 % 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 |
|---|---|---|---|---|---|---|---|---|---|---|
| Fukuoka | 12:12:05 | -18.1 | Dark | Down | 23.6 | 233.1 | Low | 12:09:05-12:15:05 | -35.5 | 0.299 | Kumamoto | 12:12:08 | -18.8 | Dark | Down | 23.8 | 233.7 | Low | 12:09:08-12:15:08 | -108.4 | 0.003 | Kagoshima | 12:12:11 | -19.6 | Dark | Down | 24.6 | 234.0 | Really Low | 12:09:22-12:15:22 | -208.1 | 0.000 |
Star training set for 20729_99XS143, (2026/06/11 12:07UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 28.35 120 4Gam Crv 12:15:48.1 -17:32:30 2.6 19.33 159 PPM 223779 11:00:11.7 -14:05:01 5.8 0.85 140 PPM 223756 10:59:26.8 -14:10:18 8.4 0.75 140 PPM 223724 10:58:02.2 -13:37:10 9.4 0.24 140 20729_99XS143 10:57:05.2 -13:40:55 16.3 139 Positions are for J2000