2023 Occultations by Trojan Asteroids - New 2023 June 7
14th Asteroids, Comets, Meteors Conference in Flagstaff, AZ, June 18-23
A massive SWRI/IOTA effort was made for the Polymele/Shaun Feb. 3 evening; SwRI/NASA paid most observer costs and provided most of the equipment
Over 90 stations were deployed across central Kansas; It was the only good Lucy-target Trojan occultation of 2023
There are some other valuable Trojan occultations during the rest of 2023 such as an occultation of a 9.6-mag. star by Hektor on Aug. 12 from Arizona
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 .pdf document will be updated less frequently than this page. _ _ _ _ _ 14th ASTEROIDS, COMETS, METEORS CONFERENCE, JUNE 18-23 This conference, abbreviated ACM 2023, will be held in Flagstaff and online later this month. Clicking on "Program and Presenter Information", including the program with links to abstracts, you can see the interesting agenda, including several papers using results from occultation observations. Some of the Trojan occultation-related abstracts are linked to below. The virtual registration fees are low enough ($200) that some amateurs may be interested in attending; some amateurs may qualify for the cheaper student rate. In-person registration is open through June 9 and will re-open on site on June 18; registration for virtual attendance is available to the last day of the conference, June 23. Occultation Results for the Polymele System - a Lucy Target Interpreting the Occultations by Polymele Upcoming Occultations by Lucy targets There are more abstracts about occultations by near-Earth asteroids, especially by Didymos, with links that will be given in a soon-to-be-updated version of the IOTA NEA occultations page. _ _ _ _ _ 2023 Feb. 3/4 OCCULTATION BY LUCY TROJAN (15094) POLYEMELE, USA, S.E. CANADA, IBERIA This was the largest effort ever untaken for an occultation by a Lucy Trojan asteroidal occultation in North America. Over 90 stations were spread across central Kansas at 2-km intervals, with these goals for the project that was organized by the Southwest Research Institute and NASAs Lucy mission to explore Trojan asteroids. Information about the campaign is here. As you can read in the main Trojans occultations .pdf document, the Feb. 3/4 occultation by Polymele was the best Lucy-target occultation of 2023 in the USA; there are no others, of mag. 14.0 or brighter, for which SwRI campaigns are likely this year. We apologize for not completing and posting this page before this important occultation; instead, we relied on SwRI's information posted about the event, and email messages describing the event and SwRI's plans for it, sent mainly to the IOTAoccultations groups.io list. Most communication about the event was via lucyocc.slack.com. Those interested in participating in any of the SwRI expeditions are strongly encouraged to join that Slack workspace; to do that, send a message to Brian Keeney, email bkeeney at gmail dot com . As far as we know, no observations were made, or even attempted, of the Polymele occultation on Jan. 10. _ _ _ _ _ OCCULTATION OF SAO 60194 BY (624) HEKTOR, 2023 AUGUST 12 This is the brightest Trojan occultation in North America during 2023. Hektor is the largest Trojan asteroid and, as noted in the .pdf document, an interesting contact binary object. The star is also known as UCAC4 627-040447, BD +35 deg. 1646, and PPM 72936; its spectral type is F8. The star, WDS 07346+3519 = MLB 931, has a 12th- mag. companion 3" away in PA 337 deg. that will not be occulted; the diameter of Hektor, almost 200 km, will subtend only 0.04"; it will be 15th mag., much fainter than the companion star. So instead of a 6-mag. drop when the occultaion occurs, it will probably appear as a 3-mag. drop, still very strong, with a central duration of about 5s. Closer to the time of the event, we'll get a predicted shape model for the occultation, and in a few weeks, the Lucky Star prediction should become available, which should include a prediction for the path of Hektor's 12-km satellite, Skamandrios, in a 3-day orbit about 620 km away. The occultation will only be visible from parts of Arizona, northern Baja California Norte, and northwestern Sonora state. By the time the path reaches New Mexico, the twilight will be too bright; southwestern Arizona will be the sweet spot, with an event altitude of 18 deg. and Sun alt. -14 deg.; let us know if you might be interested in joining our expedition for this bright important event. Files for the event are available below, but the final path may be a little different: Occult map Arizona map generated from Derek Breit's Google map. Path data _ _ _ _ _ OCCULTATIONS BY (617) PATROCLUS AND MENOETIUS During 2023, there are no occultations of stars brighter than mag. 14.0 by the interesting (617) Patroclus/Menoetius binary asteroid system, the last target of NASAs Lucy mission, in North America, and even the few there between mag. 14 and 16 cross areas with no known observers and few resources. But there are a few good Patroclus/Menoetius events in other parts of the world, including India, s. Africa and Patagonia, and Australia, so for them, if observations are planned, we will need to ask SwRI to compute predictions, since the JPL Horizons orbit is now a few path-widths in error. _ _ _ _ _ 2022 OCTOBER 23RD BRIGHT OCCULTATION BY EURYBATES RESULTS A large effort was made for the 2022 October 23rd occultation of an 8.7-mag. star by Eurybates in western Europe. SwRIs prediction page for the event is at http://lucy.swri.edu/occ/20221023Eurybates/ . Well over 100 stations tried the event, but most were clouded out; 15 positive chords were recorded across the asteroid, mainly by French observers who found breaks in the widespread cloud cover; one station in northern Sweden redorded it. Euraster has a sky-plane plot of the chords. and observation details are here. _ _ _ _ _ OCCULT INPUT .XML FILES FOR 2023 ***CHANGE FROM 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 11 Trojan events mapped and tabulated in the main .pdf document Worldwide Lucy Trojan events to mag. 16 Worldwide events for our selected Trojans to mag. 14; these include non-Lucy Trojans ocvered by the Lucky Star Project, which usually will have better predictions for them. Currently, the SwRI Lucy occultations prediction site only has future occultations by Polymele, but predictions for some of the events by other Lucy mission targets will likely be added during the next few months. If you want to try to observe any of the occultations by Lucy Trojans, you should send a message to Brian Keeney, email bkeeney at gmail dot com, giving the date, asteroid, and general area, and he can prepare and post a Google map for the event. Our predictions for occultations by 11351 Leucus are quite accurate because SwRI published details of the observations they collected from several of their occultation campaigns, and those have been incorporated into the JPL Horizons system that IOTA relies on for most of their predictions, but for the other Lucy targets, our paths can be more than a path-width in error and only SwRI has accurate orbits for them. Also, see the page of bright 2023 asteroidal occultations in North America. Besides giving information about the brightest main-belt asteroidal occultations in North America during 2023, it has links to pages for occultations by other important occultations in North America, including near-Earth asteroidal occultations and special main-belt asteroidal occultations (objects with known or suspected moons, unusual shapes, etc.). ______ David and Joan Dunham, 2023 June 7 e-mail: dunham@starpower.net cell phone: 301-526-5590