First HI images with Apertif

© astron

Recent months have seen steady progress with Apertif, and more and more the system can be used to do real astronomical observations. One of the main changes that have been implemented is that fringe stopping can now routinely be used during observations instead of applying it off-line, after the observation. Applying fringe stopping off-line is only an approximation and the images clearly suffered from this.

With the latest changes, the data are much easier to handle and the calibration and reduction can now be done in exactly the same way as with the 'old' WSRT. As a result, more and more images are being made now with Apertif.

An example is given below. The left panel gives the distribution of the atomic hydrogen (contours) in the well-known galaxy M51 (grayscale). The right panel gives a movie of the HI distribution in the various channels of the observation, superposed on the continuum image which was also made from these Apertif data.