2022 Occultations by Special Main-Belt Asteroids - Updated 2022 Aug. 18
August 20 early morning (319) Leona (asteroid to occult Betelgeuse) reminder
Other good Leona occultations, Aug. 28 S. America and Nov. 10 S.E. Asia
(172376) 2002 YE25 - Another probable binary asteroid discovered by Gault and Nosworthy - US events Sept. 13 and Oct. 4 early pm
Predictions and Procedures for the Aug. 8 (90) Antiope components paths
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. _ _ _ _ _ Important Occultations by (319) Leona On December 12 next year, the asteroid (319) Leona will occult Betelgeuse in a path crossing the Florida Keys and southern Europe to Turkey; Steve Preston's prediction page for the event gives current path information, etc. The angular size of Betelgeuse is a little larger than that of Leona, so nominally, no complete occultation will occur, but only a deep annular event. Exactly what will happen will depend critically on the size and shape of Leona (we don't have any past multi-chord occultations by Leona, but rotational light curve observations suggest an elongated object) as well as on Betelgeuse, famously variable with possible clouds of dense material obscuring parts of the star. So there could be a brief total occultation for some, in the middle of a possibly complex gradual event lasting of the order of 10 seconds, a striking visual appearance. To better prepare for the event, we want to observe occultations of as many other stars by Leona as possible before December 2023, from multiple stars when possible. There are two opportunities during the rest of August, including one TONIGHT in southern Florida; see below. These should have among the highest priority for IOTA, and other occultation, observers, the only other occultations that are more important are those by Didymos, as discussed on IOTAs and ACROSSes Near-Earth Asteroid occultations pages. 2022 AUGUST 19/20 (Star 12.8mag UCAC4 448-138751, mag. drop 2.1, max. duration 5.3s) This is TONIGHT, just after 1:13 am EDT (5:13 UT) of August 20. Terry Redding is trying to encourage observations of the event from the West Palm Beach region; here is his call for observations with information about the event, and GOOD BACKGROUND INFORMATION from Dave Herald and John Irwin about this and other upcoming Leona occultations. For tonight's event, you are encouraged to use Occult Watcher (the event is on the North American "low mag." feed set up by Steve Messner), especially for its Google map and coordination with other observers, and below are some useful links and files (mainly from Terry Redding): The OW Cloud page has good Aladin zoomal star charts and a zoomable path map, and event details. The target star is a little east of the Water Jug of Aquarius. The Occult map of the path over Mexico and southern Florida. The good NWS cloud forecast for Florida. A map of the path over southern Florida. Using Google Earth with John Irwins .kml file, you can click on the circled dots to find out the predicted U.T. and circumstances. AUGUST 28 (Star 11.8mag TYC 5233-00907-1, mag. drop 2.8, max. duration 4.9s) This occultation is good for Brazil, and maybe the European and US observatories just north of Santiago, Chile, as well as northern Argentina. The Occult map of the path over South America John Irwins .kml file 2022 NOVEMBER 10 (Star 12.7mag UCAC4 412-133663, mag. drop 2.9, max. duration 6.4s) This occultation is good for eastern India, and Luzon Island, a short distance north of Manila. The Occult map of the path over S.E. Asia 2023 JANUARY 1 (Star 10.5mag TYC 5248-00437-1, mag. drop 5.5, max. duration 2.0s) This occultation is good for Skagway, Alaska; near Whitehorse, Yukon; and Great Bear Lake. The local date is Dec. 31, 2022, after sunset, with bright dusk twilight, darker to east. The Occult map of the path over northern N. America. A bright Didymos occultation near the same time, shown on IOTAs NEA occultations page for 2022 across the USA and eastern Canada, will be more important to travel for. Occultations by Leona during 2023 will be posted later, when many other 2023 occultations will be documented. _ _ _ _ _ BRIGHT AUGUST 8TH OCCULTATION BY (90) ANTIOPE ACROSS NORTH AMERICA This .pdf document has many maps showing the paths of the occultations by both components of Antiope. Maps of the path in areas where the occultation was not observed have been removed in this version; the original with all of the maps is available by email upon request. The star that was occulted Aug. 8 by Antiope was 9.2-mag. SAO 189554 = TYC 6343-01777-1, spectral type K5, 1.4 degrees west of 5.9-mag. 17 Capricorni, around 7:20 UT of Aug. 8 UT, in a path extending from Quebec to Texas, and on to Baja California, and Hawaii; it was the brightest star occulted by Antiope anywhere in the world this year. (90) Antiope is a binary asteroid, with roughly equal-size components, so it needs to be handled differently from other events. A version of the Occult map (a view of the Earth as seen from the direction of Antiope) zoomed in to show part of the path in more detail over central North America is here; dots mark the locations of the larger cities. Also included on the map is the projection of the ISAM shape model of the two components, correctly projected for the time of the occultation, showing how their shadows will be oriented relative to the path that is predicted for a fictitious single spherical object at the center of mass of the system with a surface-area equivalent to the sum of that for the two components. For the projected ISAM shape model, the northern component is green while the southern one is brown. Of course, due to their orbital motion, the configuration of the two components will be different for other occultations. Links to similar detailed Occult maps with the larger cities, but WITHOUT the ISAM model, are below: Eastern North America northwestern Mexico Hawaii A finder chart showing the FOV for a 120mm refractor is here; more finder charts are on Steve Prestons page for the occultation. Zoomable Aladin finder charts are on the OW Cloud page for the event, but DO NOT use its path maps. For the August 8th occultation, you can use this Google Map to plot the Antiope component occultation limit in your area. Alternatively, you can use Derek Breits Google map. It has the advantage of more robust centering with the cursor, and if you left-click on a point, the height above sea level (elevation) in meters is displayed. The offsets to use, entered into boxes just above the Google Map, are +154 and +21 for the northern Antiope component (green on the ISAM diagram), and -39 and -166 for the southern component (brown on ISAM). These offsets are not the same as the OW distances, which place the limits 85.5 km from the center rather than the 87.1 km we found for the Google Map, as explained this .pdf document that gives procedures for calculating and plotting the paths for the separate Antiope components so others can do this for future Antiope occultations in their areas. Only two offset lines can be plotted at a time with the Google Map. The overall 1-sigma prediction accuracy is 5 km, but the shape model errors that could amount to 10 km or more (we want to improve those with your observations). There is some news that Google Maps may no longer be supported, and could become inoperable, starting August 1, which is why I produced the document with several detailed maps noted above. But it is now August 18 and the interactive Google maps are still working, so we are not sure when, or even if, they will stop working this month. The limit distances for OW are +160.5 and +22.5 for the northern component, and -40.5 and -173.5 for the southern one. Links to some of the files mentioned in the procedures document, are given below. The Occult input file for the Aug. 8th Antiope occultation is here, from Steve Preston's Web site. The Central North American Occult map WITHOUT the ISAM model projected on it is here. A link to the ISAM model for this event is given near the top of this section. The PowerPoint file is here. There were 3 positives that you can see on the Aug. 8 Antiope line of the North American asteroidal occultation results page. _ _ _ _ _ Also, note that later on Aug. 8, actually on Aug. 9 UT, there was an important but faint (15th mag.) occultation by the large TNO Quaoar, visible from a wide path that crossed most of the lower 48 USA, as described in this Lucky Star call for observations. Here is the link to the Lucky Star prediction page for the event. There were several observations of that event, including 3 positives that you can see on the Aug. 9 Quaoar line of the North American asteroidal occultation results page. _ _ _ _ _ In an earlier version, I wrote about the Aug. 3 Viipuri event: Two past occultations had single-chord detections of a possible satellite of (2258) Viipuri, as noted in the .pdf document, so observations of more occultations by Viipuri are sought, including the one tomorrow night. Unfortunately, in North America, the Aug. 3 occultation will be visible in dark-enough skies only from southern Georgia, where the National Weather Service forecasts will be quite cloudy. However, this is a trans-Atlantic event, also visible from Iberia, where hopefully, conditions will be better. More details are on Steve Prestons prediction page for the event. Observers in Europe were alerted to the north shift from an earlier prediction and Oscar Canales recorded an almost 4s occultation from a mobile site in Spain. _ _ _ _ _ (172376) 2002 YE25 On June 22, the discovery of another probable binary asteroid by D. Gault and P. Nosworthy, (172376) 2002 YE25, was announced on IOTAoccultations and other lists; more recently, a CBET announcing this was distributed by the Minor Planet Center. It's probably a miniature Antiope-like system with 4-km components separated by at least 15 km. The discovery observation, made on 2022 May 16, involved an 11.0-mag. star and enabled a significant improvement of the orbit of the asteroid. That has been used to compute occultations by it of stars to mag. 14.0 for the rest of 2022; the Occult .xml input file for the 43 occultations found is added to the others with links in the last section below. There will be occultations by the object(s) in the USA on September 14 and October 5, U.T. (both occur the evening before, local time). Those outside of North America are encouraged to download the Occult .xml file and use Occult to see if any occultations by 2002 YE25 will be visible in their area. _ _ _ _ _ CLOUD COVER FORECAST MAPS For some past events, I have posted cloud cover forecast maps, but with time constraints, I will rarely do that in the future. Expedition organizers, mobile observers, and others are encouraged to use the Web sites I use, given here. _ _ _ _ _ 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. Worldwide special main-belt events to mag. 14, 511 occultations, not including (4337) Arecibo, (4552) Nabelek, and (33074) 1997 WP21 For the 12 special main-belt asteroid events mapped and tabulated in the main .pdf document North American special main-belt events to mag. 14, 21 occultations Worldwide events (62) for (4337) Arecibo to mag. 16. Worldwide events (149) for (2258) Viipuri to mag. 14. Worldwide events (29) for (33074) 1997 WP21 to mag. 14. Worldwide events (59) for (4552) Nabelek to mag. 14. Worldwide events (59) for (172376) 2002 YE25 to mag. 14. Worldwide events (16) for (319) Leona to mag. 14. ______ David and Joan Dunham, 2022 August 18 e-mail: dunham@starpower.net cell phone: 301-526-5590