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Submitter: Tom Oosterloo (for Apertif Commissioning Team)
Description: Astron will soon operate two world-class telescopes, Lofar and Apertif. In other places in the world, telescopes like Lofar and Apertif are operational (or soon will be). But what is unique to Astron is that Lofar and Apertif are a perfect match to each other and that the combined capabilities are much more powerful than those of each instrument separately.

This is because the relative sensitivities of the two instruments match that of the typical radio source. In other words, the average radio source is imaged by both instruments with the same signal to noise and resolution. This is unique. Because Lofar and Apertif operate in very different frequency bands, such combined images give much more additional information on the nature of the objects compared to the single images.

A corollary of the above is that if a source looks very different in both images, the source is not typical, and is therefore, like atypical people, likely much more interesting. To illustrate this, the movie shown above blinks between a Lofar image and an Apertif image of the same piece of sky (part of the Lockman Hole). Many sources show up in both images, but there are some sources, in particular extended ones, that only Lofar sees. These turn out to be sources that are very old; they have lost most of their energy and only still shine at low frequencies. This is a very interesting class of objects because they give a new view of what happens when radio sources grow old. Because of the large field of view of both telescopes, many many of such sources will be discovered.
Copyright: Astron
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