Daily Image

05-12-2012
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A globular cluster?

Submitter: Michiel Brentjens
Description: Well, not really. This beautiful image, created by Astron's Sarod Yatawatta, was recorded for the LOFAR Epoch of Reionization key science project on November 5th, 2012. At 30 by 30 degrees, it depicts a very wide view of the north celestial pole. All Dutch LOFAR stations gazed at the target for 12 hours straight using 70 MHz of bandwidth.

The source density in the image varies proportionally to the sensitivity of the LOFAR station beam: many sources at the centre, very few in the first null — a narrow ring around the main beam — followed by more sources in the first side lobes of the beam, scattered throughout the picture.

This low resolution image is only 3200x3200 pixels, with a 2 arc minute FWHM point spread function (PSF). Near the centre, every pixel contains at least one source! The image at the full LOFAR-NL resolution of 6 arc seconds contains of order one billion pixels, and has a noise level of about 100 micro-Jy per PSF!
Copyright: (c) ASTRON 2012
 
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