Occultation event with (23958) 98VD30, event index number 953
Regions able to see the event: Japan
Geocentric closest approach at 2025/05/07 12:52:24 UTC
J2000 position of star is 08:51:09.1 -08:08:17
Equinox of date position of star is 08:52:23.4 -08:14:03
Star is 41 degrees from the moon. Moon is 78% illuminated.
Stellar brightness G=16.0, apparent brightess of occulting body is G=15.5
Use an exposure time of 0.60 seconds with the standard RECON-QHY system.
SNR of 3.1 per integration for unocculted signal
Expected flux drop is 39% with SNR of 1.2 for the occulted depth (per occulted point)
Apparent velocity is 18.1 km/sec on the sky relative to the star, or, 19.0 arcsec/hr.
Position angle of asteroid motion is 63.2 degrees
The recommended exposure time corresponds to 10.9 km per image.
The 1-sigma error in the time of the event is 1.6 seconds.
The 1-sigma cross-track error in the shadow position is 30.7 km.
The sky-plane scale is 3433.1 km/arcsec.
Diameter estimates:
55.0 km assuming a 5% albedo, aximum of 3.0 sec for a central chord
22.4 km assuming a 30% albedo, maximum of 1.2 sec for a central chord
Cross-track diameter of 46.0 km used for deployment plan.
Star training set for 23958_98VD30, (2025/05/07 12:52UT) Object RA Dec mag sep mel Regulus 10:09:43.2 +11:50:32 1.3 27.80 21 Alphard 09:28:50.0 -08:46:11 2.0 9.03 32 15 Hya 08:52:49.2 -07:16:26 6.0 0.97 40 PPM 191792 08:53:40.9 -07:49:40 8.3 0.52 40 PPM 191762 08:52:01.1 -08:10:37 8.8 0.11 41 23958_98VD30 08:52:23.4 -08:14:03 15.5 41 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 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 23958_98VD30, (2025/05/07 12:52UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 27.80 21 Alphard 09:27:35.2 -08:39:30 2.0 9.03 32 15 Hya 08:51:34.3 -07:10:39 6.0 0.97 40 PPM 191792 08:52:26.3 -07:43:52 8.3 0.52 40 PPM 191762 08:50:46.7 -08:04:52 8.8 0.11 41 23958_98VD30 08:51:09.1 -08:08:17 15.5 41 Positions are for J2000