Occultation event with (17171) 99NB38, event index number 1414
Regions able to see the event: US,Europe,NMexico,SMexico
Geocentric closest approach at 2025/10/26 01:44:34 UTC
J2000 position of star is 03:02:07.0 +48:58:47
Equinox of date position of star is 03:03:54.9 +49:04:48
Star is 146 degrees from the moon. Moon is 18% illuminated.
Stellar brightness G=16.0, apparent brightess of occulting body is G=15.7
Use an exposure time of 0.65 seconds with the standard RECON-QHY system.
SNR of 3.3 per integration for unocculted signal
Expected flux drop is 41% with SNR of 1.4 for the occulted depth (per occulted point)
Apparent velocity is 15.3 km/sec on the sky relative to the star, or, 17.5 arcsec/hr.
Position angle of asteroid motion is 90.7 degrees
The recommended exposure time corresponds to 9.9 km per image.
The 1-sigma error in the time of the event is 0.5 seconds.
The 1-sigma cross-track error in the shadow position is 27.5 km.
The sky-plane scale is 3145.3 km/arcsec.
Diameter estimates:
46.1 km assuming a 5% albedo, aximum of 3.0 sec for a central chord
18.8 km assuming a 30% albedo, maximum of 1.2 sec for a central chord
Cross-track diameter of 40.9 km used for deployment plan.
Star training set for 17171_99NB38, (2025/10/26 01:45UT) Object RA Dec mag sep mel Aldebaran 04:37:24.3 +16:33:33 0.8 37.66 164 Mirphak 03:26:10.8 +49:57:03 1.8 3.72 148 Iot Per 03:10:56.7 +49:42:35 4.0 1.31 146 PPM 045704 02:59:41.5 +48:58:50 8.5 0.70 145 PPM 045811 03:05:46.6 +49:29:32 9.1 0.51 146 PPM 045767 03:03:03.0 +49:24:02 10.3 0.35 145 17171_99NB38 03:03:54.9 +49:04:48 15.7 146 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 1.6 % 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 |
|---|---|---|---|---|---|---|---|---|---|---|
| Naylor Obs | 01:49:28 | -41.5 | Dark | Down | 47.3 | 57.2 | Up | 01:46:28-01:52:28 | 134.3 | 0.000 | Ryan Obs | 01:49:27 | -42.0 | Dark | Down | 47.5 | 57.1 | Up | 01:46:27-01:52:27 | 75.6 | 0.016 |
Star training set for 17171_99NB38, (2025/10/26 01:45UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 37.66 164 Mirphak 03:24:19.4 +49:51:40 1.8 3.72 148 Iot Per 03:09:07.3 +49:36:46 4.0 1.31 146 PPM 045704 02:57:54.3 +48:52:42 8.5 0.70 145 PPM 045811 03:03:58.1 +49:23:34 9.1 0.51 146 PPM 045767 03:01:14.9 +49:18:00 10.3 0.35 145 17171_99NB38 03:02:07.0 +48:58:47 15.7 146 Positions are for J2000