Israeli scientists from the Weizmann Institute of Science built a unique telescope

The new observatory, built near Kibbutz Neot Smadar, is composed of 32 telescopes, each of which has a 28-cm.-diameter mirror. The system is planned to be expanded later this year, and will eventually comprise 48 telescopes, at which point it will have a light-gathering power equivalent to that of a 1.9-meter-diameter telescope, making it the telescope with the largest field of vision in the world, with a sky-scanning capability three times greater than that of any other observatory.

David Polishook, director of the new observatory, explained there this week to Haaretz, “The more one enlarges the telescope mirror, the more light will be gathered, but this makes it difficult to increase the field of vision. Therefore, telescopes with large mirrors are usually characterized by a reduced field of vision. This reduction does not pose a problem if the observation is directed at a known phenomenon, such as a specific star or galaxy, but if scientists wish to identify temporal events, in which the timing and location of occurrence is unknown, then a wide field of vision is required. Such a field of vision may be achieved when numerous telescopes are combined with relatively small mirrors.”

When the observatory is completed by year’s end, the new telescope will have a field of vision of 350 square degrees. For comparison’s sake, Polishook says, the area taken up by the moon is about one-quarter of one square degree. “In other words, the telescope can see a piece of sky that is equivalent to 1,400 times the surface of the full moon.”

The most expensive telescope ever developed, the James Webb, has a very large mirror diameter and a tiny field of vision – about one-thousandth of one square degree.

“Imagine a military force,” Polishook continued. “Our system is like a reconnaissance soldier who is searching for targets. Once he spots them, large telescopes will be able to better observe them.” Telescopes of the sort built in the Arava are therefore called ‘sky survey’ telescopes.

In two years or so, a new telescope named after the American astronomer Vera Rubin will become operational in Chile, Polishook states. Until that time, he notes, “our telescope is the most efficient sky survey, in terms of its chances of discovering temporal space phenomena.”

The Vera Rubin telescope will cost approximately $1 billion; James Webb cost about $10 billion; meanwhile, the telescope in the Arava Desert will cost a mere $2 million or so. “It consists of 48 off-the-shelf telescopes; that is something that everyone can do,” explains Polishook.

The project was initiated by Weizmann Institute Prof. Eran Ofek. “One of the things that drew us to this project is that the new telescopes we’re talking about require an investment of billions of dollars, and decades of work. Therefore, in Israel you have to find ways around this problem,” he says.

The future of astronomy, he believes, depends on building multiple small-telescope systems. “There are other groups around the world that have also come to this conclusion, but we started first and we are therefore the leaders in this field,” says Ofek.

The telescopes scan the entire sky once an hour, and are capable of noticing stars whose light intensity is 1,000,000 times smaller than what the human eye is capable of seeing. This generates an immense quantity of data, and an important part of the system is the code that analyzes this data. An additional advantage of the new system is its great flexibility, Ofek noted.

“We can do many types of science with it. Dr. Sagi Ben-Ami is using it to search for planets outside the solar system, David [Polishook] is looking at asteroids, and I am looking at supernovas and other transient events,” said Ofek.

Polishook says the observatory is helped in its task by “the light pollution discipline” of residents of the adjoining Kibbutz Neot Smadar. “Because it’s very important to them, as well, to enjoy the night sky. We are hoping that the Israeli army bases in the area will also follow in their footsteps. Two years ago, there was nothing here, and now there’s a garden of telescopes in the desert. Ben-Gurion would be pleased; we built an observatory in the Arava, we’ve made the wilderness bloom.”

Gid'on Lev