Abigail Klein Leichman
March 24, 2014


The Wise Observatory in Mitzpeh Ramon. Photo by Ira Machefsky
The Wise Observatory in Mitzpeh Ramon. Photo by Ira Machefsky

During the night between Tuesday March 4 and Wednesday March 5, a rare astronomical event was observed at Tel Aviv University’s Wise Observatory near Mizpeh Ramon in the Negev Desert: the occultation of a star some 50 light-years away by a solar system object that belongs to the Pluto family.

No other observatory in the world was able to view it for the 43 seconds it lasted.

A star occultation is similar to a solar eclipse — when the sun is blocked by the moon and a narrow shadow falls on a small part of the Earth. In this case, a distant star was blocked by a tiny distant dwarf planet, or Plutino, known as Asteroid No. 2003 VS2. This asteroid only circles the sun every 246 years.

The occultation was predicted by the French astronomer Jean Lecacheux, but he could not be sure exactly where the unusual event would be observable.

On the chance that Israel would be that spot – and it was! — astronomers Shai Kaspi and Noah Brosch readied two telescopes to watch the occultation at the Wise Observatory. One was the large telescope that the observatory has been operating since 1971, while the other is the brand-new Jay Baum Rich telescope equipped with a smaller primary mirror of 0.7-meter diameter.

Both these sophisticated machines image the sky with large-format CCD cameras way more sensitive than the human eye. The larger telescope took pictures every four seconds; the new telescope captured images every five seconds.

A few minutes before 10pm, the scientists noticed one of the stars in the field disappeared — a clear sign that the occultation had begun. Exactly 43 seconds later, the star reappeared on the telescopes’ screens.

The data are now being analyzed together with data from a similar event observed in December 2013 from Réunion Island in the Indian Ocean in order to determine the exact shape of the asteroid and whether it has any moons.

To learn more about astronomy in Israel, see https://www.israel21c.org/headlines/starry-starry-israeli-night/.

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