2022 Occultations by Trojan Asteroids - Updated 2022 September 21

Faint Eurybates occultation over Washingon State, Sept. 20 dawn

Challenging 12.7-mag. occultation by Patroclus, Oct. 5 pm, over Los Angeles

These occultations are described and illustrated in this .pdf document. 
It includes several hot links to external Web pages, but links to internal files, 
especially the .xml input files used by the Occult program, are given below. 
The .pfd document has NOT been updated with the new information about the two 
Jovian moon occultations (Pasaiphae and Ananke) on Sept. 14 UT, or the new 
Eurybates event on Sept. 20; links to maps and other data for those events are 
given below. The .pdf document does include a map for the Oct. 5/6 occultation 
by the Lucy Trojan Patroclus/Menoetius system over southern California.

To save space on the server where this page is hosted, some of the larger files 
for past occultations have been removed, so you will get broken links for them. 
If you want a file that is not available, we can send it to you upon request.

Predictions for the occultations of stars by both (617) Patroclus and its moon, 
Menoetius, that occurred in Australia on June 30, and on July 6, 22, 25, and 28,
are given on this Web page of the Southwest Research 
Institute (SwRI). The SwRI and Australian teams observed these with at 
least 10 telescope systems that were shipped to Australia in time to also 
observe an occultation by Pluto on June 1. One of the stations for that 
effort in Northern Australia was close enough to the actual central line, as 
predicted by the Lucky Star Project, to record a bright central flash caused 
by the focusing of the star's light by Pluto's atmosphere.
_ _ _ _ _

2022 OCT. 5/6 OCCULTATION BY PATROCLUS/MENOETIUS OVER SOUTHERN CALIFORNIA

An occultation of a 12.7-mag. star by Patroclus and Menoetius will be visible 
at low altitude and in evening twilight across southern California, as described 
in the .pdf document with link at the top of this page. The Google Earth 
file provided by SwRIs Brian Keeney is here. A file with the predicted 
central Universal Time, and star and sun altitudes, for dozens of locations 
are in this plain text file; download the file and edit it with Notepad 
or another word processor, so you can search for your city or observatory, 
or one near your location. The occultations should occur within +/-40 seconds 
of the listed U.T., with the occultation by each component lasting 5 seconds 
or less. BUT it used OLD, INCORRECT path data, so only the times and 
circumstances (altitudes of the star and Sun) are valid.

A Lucky Star prediction for this event is on Occult Watcher (OW), but it is 
not as good as the prediction by SwRI. I have added dummy stations in OW in the 
SwRI limits and central lines for both Patroclus and Menoetius, so you can 
see their lines (black) on the OW map; use them, and ignore the green, blue, 
and red Lucky Star path lines.
_ _ _ _ _

MAJOR CAMPAIGN 2022 OCT. 23 BRIGHT EURYBATES OCCULTATION

A major campaign is being orgsanized by SwRI, IOTA, IOTA-ES, Lucky Star, and 
several regional European astronomy clubs and institutions, for the 
occultation of an 8.7-mag. star by the Lucy target Eurybates that will 
occur in a path crossing western Europe. The Occult map for the event 
is here, IOTA's prediction page for the event is here, and SwRI's page 
with the best path for the event is here. John Moore will be bringing 
several mighty mini and midi systems that can be used by local observers 
(John will train them, with help from Carles Schnabel and others) to 
record the occultation.
_ _ _ _ _

2022 SEPT. 20 OCCULTATION BY LUCY TROJAN (3548) EURYBATES, WASHINGTON STATE 

Unistellar predicts an occultation of a 14.3-mag. star by the Lucy Trojan 
asteroid (3548) Eurybates that will occur around 12:29 UT of Sept. 20; the 
Occult map for the event shows that it will only be visible from Washington 
State, with the dawn twilight too strong to observe the faint star farther 
for sites farther east, across s.e. B.C. and s. Alberta. A link to the 
Occult input file for the event is below. The Unistellar map shows a very 
large error zone, but the orbit of Eurybates is accurately-known and the 
real path errors are only 0.1 or 0.2 path-widths. I think that Unistellar 
wants to encourage their observers in a much wider zone, in order to possibly 
catch an occultation by Queta, the small distant (about 2300 km away) moon of 
Eurybates discovered by HST in 2018, but with such a faint star, it will be 
very hard to reliably detect an occultation by Queta since it would likely 
last less than 0.2s; eVscopes would have great difficulty with that.
_ _ _ _ _

2022 SEPT. 14 OCCULTATION BY JOVIAN MOON 8 PASIPHAE ACROSS N.W. USA

This Occult map shows the path of the occultation, with Universal Time 
marks at 1-min. intervals and the start of nautical twilight (Sun alt. 
-12 deg.) indicated, showing the dawn twilight will be too strong west 
of North Dakota. This NWS cloud-cover map shows the area with the best 
chance of clear skies is near where the borders of Idaho, Oregon, and 
Nevada meet; other areas look quite cloudy. Altair Ramos Gomes Junior 
has updated the prediction for this occultation using recent astrometry 
obtained in Brazil; his message about the results is here, his 
map for the occultation with the updated path is here, and the 
Google Earth file showing his new path is here; it is only about 1.5 
path-widths north of the Occult path that we computed a year ago.

About 1.5h before the Pasiphae event, there will be an occultation of 
another star, mag. 11.9, by the smaller 12th Jovian moon, Ananke, 
across southern Florida (Miami) and central Mexico, but there's been 
no astrometry so the path is more uncertain; this Occult map shows 
the path and Universal Time at 1-min. intervals.
_ _ _ _ _

Information used to coordinate observations of the June 4th occultation by 
of a 10th-mag. star by (617) Patroclus and its moon, Menoetius, in the s.w. USA 
are described in this .pdf document, but most of the files described there have 
been removed, since the event is now past. The occultation was successfully 
observed, with 7 chords across Menoetius in Arizona and 1 chord for Patroclus 
in New Mexico. The observations were reported to SwRI, which used them 
to update the predictions for the Australian occultations noted above.
_ _ _ _ _

OCCULT INPUT .XML FILES FOR 2022

When you open these files with your Web browser,
you should get a display that looks like this.
The larger files may take a couple of minutes to show this appearance, 
showing a messed-up display before then. Once the proper view appears, 
right-click anywhere on the display, then "Save as" to a directory
on your computer; the best directory is the \Asteroid\ subdirectory 
in your Occult\ directory. Better predictions are often available via 
Occult Watcher and at Steve Prestons asteroidal occultation prediction site, 
the SwRI occultation prediction Web site, and the Lucky Star prediction site,
as described near the end of the main .pdf document linked to at the top.
You can use the input files with the free Occult4 program, as described in 
this .pdf document.

For the 14 Trojan events mapped and tabulated in the main .pdf document
2022 Sept. 20 occultation of 14.3-mag. star in Washington State
2022 Oct. 23rd occultation of 8.7-mag. star in w. Europe, using the latest JPL Horizons orbit, 
  BUT for the path, you must use SwRIs prediction.
Worldwide Lucy Trojan events to mag. 16, 1731 occultations
Worldwide Polymele events to mag. 16, 175 occultations
Worldwide events (470) for selected Trojans to mag. 14;
these involve non-Lucy Trojans ocvered by the Lucky Star Project.
______

David and Joan Dunham, 2022 February 4, but updated June 14, and September 13, 14, and 21
e-mail:  dunham@starpower.net
cell phone:  301-526-5590