Occultation event with (4007) Euryalos, event index number 1730
Regions able to see the event: US
Geocentric closest approach at 2025/12/28 07:58:01 UTC
J2000 position of star is 12:49:31.0 -04:22:04
Equinox of date position of star is 12:50:51.5 -04:30:33
Star is 176 degrees from the moon. Moon is 56% illuminated.
Stellar brightness G=14.5, apparent brightess of occulting body is G=16.0
Use an exposure time of 0.50 seconds with the standard RECON-QHY system.
SNR of 9.6 per integration for unocculted signal
Expected flux drop is 79% with SNR of 7.6 for the occulted depth (per occulted point)
Apparent velocity is 15.9 km/sec on the sky relative to the star, or, 15.1 arcsec/hr.
Position angle of asteroid motion is 120.3 degrees
The recommended exposure time corresponds to 8.0 km per image.
The 1-sigma error in the time of the event is 2.1 seconds.
The 1-sigma cross-track error in the shadow position is 15.6 km.
The sky-plane scale is 3792.9 km/arcsec.
Diameter estimates:
51.8 km assuming a 5% albedo, aximum of 3.2 sec for a central chord
21.1 km assuming a 30% albedo, maximum of 1.3 sec for a central chord
Cross-track diameter of 45.5 km used for deployment plan.
Star training set for 4007_Euryalos, (2025/12/28 07:58UT) Object RA Dec mag sep mel Spica 13:26:34.0 -11:17:46 1.0 11.14 170 PPM 195939 12:54:58.7 -04:21:57 6.5 1.04 176 PPM 195846 12:48:54.6 -04:49:22 7.5 0.58 177 PPM 195862 12:50:15.3 -04:31:16 9.5 0.15 176 4007_Euryalos 12:50:51.5 -04:30:33 16.0 176 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 |
|---|---|---|---|---|---|---|---|---|---|---|
| RIT | 07:52:21 | -51.6 | Dark | Down | 21.5 | 118.7 | Not Up | 07:48:33-07:54:33 | -126.2 | 0.000 |
Star training set for 4007_Euryalos, (2025/12/28 07:58UT) Object RA Dec mag sep mel Spica 13:25:11.5 -11:09:41 1.0 11.14 170 PPM 195939 12:53:38.1 -04:13:31 6.5 1.04 176 PPM 195846 12:47:34.1 -04:40:53 7.5 0.58 177 PPM 195862 12:48:54.8 -04:22:47 9.5 0.15 176 4007_Euryalos 12:49:31.0 -04:22:04 16.0 176 Positions are for J2000