2014-03-14

Call for observation: Asteroid occults Regulus

Stargazers in Northeastern Canada and United States, get ready, this is a very rare event! In what's according to Sky&Telescope is "best and brightest 'asteroid occultation' ever predicted for North America", the main-belt asteroid (163) Erigone will occult one of the brightest stars of the night sky, Regulus, or α Leonis - it may even completely "switch" it off. The event will be visible in a large stretch that includes Long Island, New Jersey, Connecticut, New York metropolitan area, upstate New York, and Ontario. The occultation is predicted to occur next wednesday night (March 19-20) at 02:05 EDT (07:05 UTC). It may last up to 14 seconds.


Predicted path of the asteroid shadow. Shortly after 2:06 am EDT on March 20, 2014, observers between the red lines have the best chance of seeing the bright star Regulus temporarily disappear as asteroid (163) Erigone passes in front of it. Image: Geoff Hitchcox / IOTA / Google Maps
I strongly recommend to watch this event, it is very rare that a star that bright gets occulted by an asteroid. Regulus is the brightst star in the constellation Leo, the Lion, which is perfectly situated to be visible in March. Because Erigone is relatively large (73km) the occultation will last several seconds.

Looking Southwest on March 20, 2014 just after 2:06 am EDT. Regulus is the bright star marked on the chart by the two red lines.  Regulus is in the constellation of Leo, just below and to the left of the curved star pattern commonly called the “sickle of Leo.”  Image: IOTA / Stellarium

From my own experience, I recommend to observe even if you're not living in the path indicated by the map (which is, in fact, just a probable path, the true one may differ by several kilometers due to inaccuracies of the asteroid's position) but a few miles outside of it. In 2010, we tried to observe an occultation of another naked eye star in Europe, δ Oph, only to find out that the true shadow path passed about 10km more to the North!

I will not bother to write down more details here, and instead refer to the special website of the International Occultation Timing Association (IOTA) and the corresponding article on Sky&Telescope.com.

Clear Skies!

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