Imaging

When the instrument was opened the camera wheel housing and the detector where cleaned and when re-assembling NOTCam we realized that it was possible to adjust the detector plate alignment somewhat and took care to measure and align it well with respect to the camera wheel with the hope that this would remove the slight focus shift seen over the array. After mounting NOTCam and focusing fields with many stars it was found that: i) there was a smaller scatter over the field than before and, ii) that focusing now converged quicker. We believe this is the result of better alignment of the detector, and possibly also of an improved calibration of the focus pyramid implemented at the same time. Before this, focus measurements showed a larger scatter and it was more difficult to converge on a focus value.

In relatively good seeing ($<$ 0.7 arcsec) the filter and camera focus offsets was (re-)measured for all broad band filters ZYJHKs. The new values were checked and confirmed one week later, and the automatic focus corrections in the instrument setup scripts as well as the documentation were updated.