The Lockman Hole as seen by Apertif

Image may be NSFW.
Clik here to view.© ASTRON

The commissioning of Apertif is progressing steadily and observations are now being done on a regular basis. The purpose of these observations is to test and validate the system characteristics of Apertif. To do this, it is usually not necessary to use all beams to image the full field of view of Apertif because the data from one or two beams give enough information for the test performed (and it saves a lot of data reduction�). But occasionally the full field of view is used to see if everything fits together in the way it should.

The image shown above is from a recent Apertif observation of the Lockman Hole using 37 beams giving useful data over about 10 deg^2. Eight antennas were used and only 70 MHz in one polarisation. The noise of the image is 0.2 mJy/beam, so about half that of the NVSS. The final Apertif images will be ten times deeper. The calibration and imaging was done using the automated Apertif calibration procedures.

The Lockman Hole is an important region on the sky. The Galactic foreground is very low in this direction, so it is very suitable for deep extra-galactic astronomy. It has been observed in every waveband, by more or less every telescope that can see it, so there is a wealth of information available for this part of the sky. Also LOFAR has observed the Lockman Hole (there are ten other Astron/Jive Daily Images on it) and in particular the combination of LOFAR with Apertif data will be very powerful, so you will see more of this region in the near future.