* Astronomy

Alien search telescope is shelved

A monitoring system for potential extra-terrestrial communication has been shelved due to budget cuts.
The Allen Telescope Array (ATA) in California has been mothballed, according to the Search for Extra-Terrestrial Intelligence (Seti) Institute.
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Title: The Allen Telescope Array Twenty-centimetre Survey - A 690-Square-Degree, 12-Epoch Radio Dataset - I: Catalogue and Long-Duration Transient Statistics
Authors: Steve Croft, Geoffrey C. Bower, Rob Ackermann, Shannon Atkinson, Don Backer, Peter Backus, William C. Barott, Amber Bauermeister, Leo Blitz, Douglas Bock, Tucker Bradford, Calvin Cheng, Chris Cork, Mike Davis, Dave DeBoer, Matt Dexter, John Dreher, Greg Engargiola, Ed Fields, Matt Fleming, James R. Forster, Colby Gutierrez-Kraybill, Gerry Harp, Tamara Helfer, Chat Hull, Jane Jordan, Susanne Jorgensen, Garrett Keating, Tom Kilsdonk, Casey Law, Joeri van Leeuwen, John Lugten, Dave MacMahon, Peter McMahon, Oren Milgrome, Tom Pierson, Karen Randall, John Ross, Seth Shostak, Andrew Siemion, Ken Smolek, Jill Tarter, Douglas Thornton, Lynn Urry, Artyom Vitouchkine, Niklas Wadefalk, Jack Welch, Dan Werthimer, David Whysong, Peter K. G. Williams, Melvyn Wright

We present the Allen Telescope Array Twenty-centimetre Survey (ATATS), a multi-epoch (12 visits), 690 square degree radio image and catalogue at 1.4GHz. The survey is designed to detect rare, very bright transients as well as to verify the capabilities of the ATA to form large mosaics. The combined image using data from all 12 ATATS epochs has RMS noise sigma = 3.94mJy / beam and dynamic range 180, with a circular beam of 150 arcsec FWHM. It contains 4408 sources to a limiting sensitivity of S = 20 mJy / beam. We compare the catalogue generated from this 12-epoch combined image to the NRAO VLA Sky Survey (NVSS), a legacy survey at the same frequency, and find that we can measure source positions to better than ~20 arcsec. For sources above the ATATS completeness limit, the median flux density is 97% of the median value for matched NVSS sources, indicative of an accurate overall flux calibration. We examine the effects of source confusion due to the effects of differing resolution between ATATS and NVSS on our ability to compare flux densities. We detect no transients at flux densities greater than 40 mJy in comparison with NVSS, and place a 2-sigma upper limit on the transient rate for such sources of 0.004 per square degree. These results suggest that the > 1 Jy transients reported by Matsumura et al. (2009) may not be true transients, but rather variable sources at their flux density threshold.

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US radio array starts its search for extraterrestrial life.
A large array of radio telescopes has begun its first sustained search for extraterrestrial intelligence (SETI) and at rates faster than ever before. Even so, the project has scrambled to find money to stay open and reach its planned size.

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Allen Telescope Array begins all-sky surveys
With commissioning of the 42 radio dishes of the Allen Telescope Array (ATA) nearly complete, UC Berkeley astronomers are now embarking on several major radio astronomy projects, including daily surveys of the sky.

"The ATA is fast by design, covering a wide field of view, which is ideal for dedicated surveys of the sky" - Don Backer, UC Berkeley professor of astronomy and director of the Radio Astronomy Laboratory that oversees the ATA.

The array is being built jointly by UC Berkeley and the SETI Institute, a private, non-profit organisation based in Mountain View, California.
Backer estimates that 80 percent of the telescope's time will be spent on surveys, repeatedly imaging the sky that is visible from an isolated valley in Hat Creek, Califo9rnia. Among the objects the astronomers hope to find are transient radio sources, such as supernovas and gamma-ray bursts, that may last from nanoseconds to years.

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