Occultation event with (15527) 99YY2, event index number 847
Regions able to see the event: Japan
Geocentric closest approach at 2025/03/23 13:00:14 UTC
J2000 position of star is 09:15:36.5 +03:49:51
Equinox of date position of star is 09:16:55.6 +03:43:29
Star is 142 degrees from the moon. Moon is 39% illuminated.
Stellar brightness G=16.2, apparent brightess of occulting body is G=16.7
Use an exposure time of 0.70 seconds with the standard RECON-QHY system.
Expected flux drop is 38% with SNR of 3.1 per integration
Apparent velocity is 13.7 km/sec on the sky relative to the star, or, 13.1 arcsec/hr.
The recommended exposure time corresponds to 9.6 km per image.
The 1-sigma error in the time of the event is 3.3 seconds.
The 1-sigma cross-track error in the shadow position is 73.7 km.
The sky-plane scale is 3776.6 km/arcsec.
Diameter estimates:
38.7 km assuming a 5% albedo, aximum of 2.8 sec for a central chord
15.8 km assuming a 30% albedo, maximum of 1.2 sec for a central chord
Cross-track diameter of 38.7 km used for deployment plan.
Star training set for 15527_99YY2, (2025/03/23 13:00UT) Object RA Dec mag sep mel Regulus 10:09:42.8 +11:50:35 1.3 15.38 136 Alphard 09:28:49.6 -08:46:09 2.0 12.84 131 PPM 155539 09:13:31.9 +03:45:44 6.0 0.85 143 PPM 155600 09:16:10.7 +04:06:16 8.3 0.42 142 PPM 155622 09:17:25.9 +03:44:21 8.9 0.13 142 15527_99YY2 09:16:55.6 +03:43:29 16.7 142 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 3.9 % 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 |
|---|---|---|---|---|---|---|---|---|---|---|
| Akita | 13:02:35 | -42.7 | Dark | Down | 50.5 | 209.2 | Up | 13:00:14-13:06:14 | -129.9 | 0.039 |
Star training set for 15527_99YY2, (2025/03/23 13:00UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 15.38 136 Alphard 09:27:35.2 -08:39:30 2.0 12.84 131 PPM 155539 09:12:12.8 +03:52:01 6.0 0.85 143 PPM 155600 09:14:51.5 +04:12:37 8.3 0.42 142 PPM 155622 09:16:06.9 +03:50:43 8.9 0.13 142 15527_99YY2 09:15:36.5 +03:49:51 16.7 142 Positions are for J2000