Astronomers Predict Eclipse of Naked-Eye Star by an Asteroid Monday Morning, Nov. 20


The event will be visible from West Virginia to Chicago and North Dakota   Your videorecording of the eclipse can give new information about the star and asteroid.

If you are within a 65-mile (104-km)-wide band crossing the Midwest and western Canada, you can see the naked-eye star Tejat wink out for about 10 seconds as it is covered by the asteroid Sulamitis shortly before sunrise Monday morning, November 20.  Millions of early risers in Charleston and Huntington, West Virginia; Dayton, Ohio; Muncie and Gary, Indiana; Chicago, Illinois; Madison and Eau Claire, Wisconsin; St. Paul, Minnesota; Grand Forks, North Dakota; Brandon, Manitoba; and many other smaller towns in the path have a chance to see this event, the eclipse of the brightest star predicted to be eclipsed by an asteroid as seen from the U.S.A. since such predictions have been computed starting in 1975.

The eclipse will occur at 6:41 am EST in West Virginia and southern Ohio, 6:42 am EST in western Ohio and Indiana, 5:43 am CST in the Chicago area, 5:44 am in western Wisconsin and the Minneapolis area, 5:45 in central Minnesota, 5:46 in northeastern North Dakota, 5:47 in southwestern Manitoba, and 5:48 to 5:49 am CST across Saskatchewan.

The eclipse, called "occultation" by astronomers, can be seen with the naked eye, but binoculars or camcorders will give better views of it. 

The International Occultation Timing Association (IOTA) seeks videorecordings of the eclipse.  IOTA plans to analyze the observations to determine the size and shape of both the asteroid and the star, and even to map variations in brightness across the star, which is a red giant 100 times the diameter of the Sun 232 light-years away in the constellation Gemini, the Twins.  Since the star is so large, even though it is very far away, it will take 2 to 3 seconds for the edge of Sulamitis to cover and uncover it. 

Consequently, the disappearance and reappearance will be gradual.  The path where the star will be totally eclipsed will be 43 miles (69 km) wide.  This path will be flanked to the north and south by 11-mile (18-km) wide zones where the star will be partially covered for a few seconds, causing it to dim considerably, but not completely disappear. 

Therefore, the total path width, including the partial occultation zones, is 65 miles (104 km).  The path also crosses southwestern Virginia and North Carolina, but the event occurs too close to sunrise there; small telescopes will be needed there to see the star in the bright dawn twilight.

More information about the occultation, including maps showing the predicted path and full sky charts for locating the star, are given on IOTA's Web site at http://www.lunar-occultations.com/iota There is still about half a path-width uncertainty in the location of the path (it could be a little north or south of the described path) which will be reduced with the last prediction that will be posted on the web site Friday evening, November 17. 

Sulamitis is in the main belt of asteroids between the orbits of Mars and Jupiter; its orbit does not intersect that of the Earth so there is no danger of it hitting the Earth.  The items below will also be on that Web site.

FINDING THE STAR

Locating the star is relatively simple. The sky chart illustrates the directions given below, especially the one with stars and lines on the Web site.  The crescent Moon will be high in the southeast.  Look in the opposite direction, low in the west, and you will see Jupiter and Sirius, the brightest objects in the sky after the Moon.  Between Jupiter and Sirius is Orion, whose belt of three fairly bright stars is distinctive.  Above the belt is the bright red star Betelgeuse.  Far above it is the distinctive pair of bright stars, Castor and Pollux, with Pollux on your left.  Three-fifths of the way from Pollux to Betelgeuse is the moderately bright star Alhena.  Directly to the right of Alhena, by about the same distance as Castor is from Pollux, is a pair of fainter stars.  The upper left of these is Tejat, the star that will be eclipsed.

RECORDING THE ECLIPSE

Those with camcorders can easily videotape the event.  First, point at the Moon, zooming in until you focus on it.  Then switch to manual focus and leave it at that position.  Then point the camcorder at Jupiter, and make small manual focusing adjustments, if necessary, to bring it and nearby stars into focus.  Then zoom out some, and locate Betelgeuse, Castor, and Pollux, then Alhena, as described above.  Zoom in to see the fainter stars, then keep Tejat in the field of view during the minute of the eclipse in your area (the predicted time of the event is accurate to half a minute). 

We will also want the accurate time of the event, which can be done by recording the strong clear-channel station WLS in Chicago at 890 on the AM dial.  We will record that station along with accurate short- wave time signals from the time station WWV (at 5.0 and 10.0 MHz if you have a short-wave radio) to calibrate WLS.  If you successfully record the eclipse, we will need your longitude, latitude, and height above sealevel, information that can either be determined with a GPS receiver or from Web sites (enter your address at www.mapsonus.com or similar sites to get a map of your area, and set "map clicking" to "show Long./Lat.").  Height above sealevel can be found from the topographic maps at www.topozone.com. 

IOTA members in your area can help with this process, but your work will save us time to facilitate the analysis. 

If you videorecord the eclipse, send a message describing briefly what you did, your location, and your contact e-mail and telephone number to IOTA at dunham@erols.com or to IOTA, c/o D. Dunham, 7006 Megan Lane, Greenbelt, MD 20770.  We will ask you for your videotape if it might be useful for our analysis.  

MORE INFORMATION ABOUT THE STAR, TEJAT

Tejat means "foot" in Arabic since it is in the "foot" of Castor.  Astronomers usually refer to the star as "mu Geminorum" where "mu" is the Greek letter.  The "official" proper name is "Tejat Posterior" to distinguish it from the similar star near it (below and right of Tejat on the sky charts) which is rarely called "Tejat Prior" but more frequently called "Propus" or "eta Geminorum".  Tejat (Posterior) has a diameter of about 83 million miles (133 million km), 100 times that of the Sun; if it were centered at the Sun's location, Mercury would orbit beneath its surface.  Since it is 232 light-years away, the light we see now from the star left it in 1768 (uncertain by +/-15 years).

MORE INFORMATION ABOUT THE ASTEROID, SULAMITIS

Sulamitis was the 752nd asteroid discovered, so it is asteroid number 752. It was discovered by G. Neujmin and M. Belyavskis at Simeis Observatory in the Crimea on April 30, 1913.  The asteroid is estimated to be 41 miles or 61 km in diameter, but this is uncertain by several miles and its shape is not known.  At the time of the occultation, Sulamitis will be 133 million miles (214 million km) from the Earth.  Sulamits was named after the Old Testament character Sulamith, probably the Queen of Sheba. Sulamitis is a feminine form of Sulaiman, which is the Arabic form of Solomon, meaning "peaceable".   

CREDITS

The path location was predicted on November 11 by Dr. Martin Federspiel at the Freiburg Planetarium in Freiburg, Germany (e-mail martin@astro.unibas.ch, phone +49-761-2017946), using accurate observations of Sulamitis obtained by Ronald Stone at the U. S. Naval Observatory in Flagstaff, AZ (e-mail rcs@nofs.navy.mil) and by Bill Owen at Jet Propulsion Laboratory's Table Mountain Observatory near Wrightwood, CA (e-mail wmo@jpl.nasa.gov) up through November 8.  The star position was accurately measured by the European Space Agency's HIPPARCOS satellite in the early 1990's.  IOTA members Jim Stamm, Sam Falvo, Scott Degenhardt, Jan Manek, Richard Nugent, Richard Wilds, and Rob Robinson provided information used here and posted on IOTA's Web site.

CONTACT INFORMATION  

David Dunham, the president of IOTA, can be reached by e-mail at dunham@erols.com, although during the day later this week it will be quicker to reach him at david.dunham@jhuapl.edu.  He is now in California at (562) 430-2391, but later this week will be returning to Maryland, home phone (301) 474-4722, office phone (240) 228-5609 (the latter has phone mail that I will be checking frequently remotely).  Questions can also be answered by IOTA's Web master, Rob Robinson (e-mail webmaster@lunar-occultations.com) in Bonner Springs, KS or by IOTA member Scott Degenhardt in Murphysboro, TN (e-mail dega@home.com).       Joan and David Dunham 7006 Megan Lane Greenbelt, MD 20770 (301) 474-4722 dunham@erols.com

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