Occultation event with (15440) Eioneus, event index number 3783
Regions able to see the event: US,SwRI-CO
Geocentric closest approach at 2026/06/08 05:37:02 UTC
J2000 position of star is 10:45:22.3 +29:07:02
Equinox of date position of star is 10:46:49.8 +28:58:40
Star is 155 degrees from the moon. Moon is 52% illuminated.
Stellar brightness G=15.7, apparent brightess of occulting body is G=15.4
Use an exposure time of 0.75 seconds with the standard RECON-QHY system.
SNR of 4.8 per integration for unocculted signal
Expected flux drop is 44% with SNR of 2.1 for the occulted depth (per occulted point)
Apparent velocity is 19.6 km/sec on the sky relative to the star, or, 17.7 arcsec/hr.
Position angle of asteroid motion is 125.8 degrees
The recommended exposure time corresponds to 14.7 km per image.
The 1-sigma error in the time of the event is 1.2 seconds.
The 1-sigma cross-track error in the shadow position is 34.2 km.
The sky-plane scale is 3996.7 km/arcsec.
Diameter estimates:
72.4 km assuming a 5% albedo, maximum of 3.7 sec for a central chord
29.6 km assuming a 30% albedo, maximum of 1.5 sec for a central chord
Cross-track diameter of 62.5 km used for deployment plan.
Star training set for 15440_Eioneus, (2026/06/08 05:37UT) Object RA Dec mag sep mel Regulus 10:09:46.6 +11:50:13 1.3 19.19 164 68Del Leo 11:15:30.6 +20:22:42 2.6 10.78 164 44 LMi 10:51:20.6 +27:50:01 6.0 1.51 157 PPM 100591 10:44:39.1 +29:14:45 8.2 0.55 155 PPM 100613 10:46:22.3 +29:22:32 9.4 0.41 155 15440_Eioneus 10:46:49.8 +28:58:40 15.4 155 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 31.0 % 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 |
|---|---|---|---|---|---|---|---|---|---|---|
| Patrick | 05:39:08 | -28.8 | Dark | Down | 28.5 | 287.2 | Really Low | 05:35:09-05:41:09 | -41.9 | 0.310 |
This table contains the target star visibility for registered SwRI-CO 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 0.1 % 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 |
|---|---|---|---|---|---|---|---|---|---|---|
| Dunrhomin | 05:38:40 | -24.1 | Dark | Down | 29.3 | 284.8 | Low | 05:35:40-05:41:40 | 161.2 | 0.000 | TinkerMill | 05:38:41 | -24.2 | Dark | Down | 29.2 | 284.9 | Low | 05:35:42-05:41:42 | 160.3 | 0.000 | Nikitin | 05:38:41 | -24.3 | Dark | Down | 29.3 | 284.9 | Low | 05:35:41-05:41:41 | 155.4 | 0.000 | CU-SBO | 05:38:42 | -24.3 | Dark | Down | 29.3 | 284.9 | Low | 05:35:42-05:41:42 | 150.1 | 0.000 | Nederland | 05:38:42 | -24.3 | Dark | Down | 29.4 | 284.8 | Low | 05:35:41-05:41:41 | 141.9 | 0.001 |
Star training set for 15440_Eioneus, (2026/06/08 05:37UT) Object RA Dec mag sep mel Regulus 10:08:21.9 +11:58:02 1.3 19.19 164 68Del Leo 11:14:06.8 +20:31:22 2.6 10.78 164 44 LMi 10:49:53.7 +27:58:27 6.0 1.51 157 PPM 100591 10:43:11.3 +29:23:06 8.2 0.55 155 PPM 100613 10:44:54.6 +29:30:54 9.4 0.41 155 15440_Eioneus 10:45:22.3 +29:07:02 15.4 155 Positions are for J2000