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The first source discovered by MSSS: a new giant radio galaxy!

Submitter: George Heald
Description: LOFAR's imaging commissioning survey, MSSS, is well underway. At the time of writing, about 80% of the LBA survey area, and 10% of the HBA survey area, has been observed (check this page for up to date numbers!). While sifting through the large number of processed images from the HBA survey, some familiar sources have already been recognized. But it is the new sources that really catch our attention! Especially outside of the area covered by the WENSS survey, MSSS has the potential to uncover previously unknown objects. So it is not surprising that the first new source uncovered by MSSS is at a declination of only 10 degrees....

The first source newly discovered by MSSS is shown in today's image. Identified as a giant radio galaxy (GRG), it is larger in angular extent than the full moon! It was not recognized in previous radio surveys. Its physical size is about 2 Mpc (about 6.5 million light years), at a distance from Earth of about 750 million light years. The MSSS source is associated with one of three galaxies that make up the galaxy triplet UGC 9555. The galaxy triplet is highlighted in the inset (image from the Sloan Digital Sky Survey SDSS), while the MSSS source itself is overlaid with the blue-white colors that sprawl across the image. Radio sources that are this large have been found before, though this one is particularly faint for its size. LOFAR's MSSS is well suited to finding more of this type of radio galaxy, because it is very sensitive to large, old sources.

MSSS is designed to produce a catalog of the brightest sources in the northern sky, to aid in the calibration of deeper imaging surveys that will be pursued with LOFAR in the coming years. We expect that new sources like this one will naturally result from the MSSS effort - stay tuned for more!
Copyright: MSSS/LOFAR
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