Detector

Since the pressure sensor was disconnected from the controller the average noise is at a level comparable to that measured in the lab. However, some different noise has now been reported that has the form of adjacent bright and dark pixels with an interval of approximately every 176 pixels along the readout direction, and can clearly be seen in bias frames. May tests have been done to try and locate the source of this noise but to-date it still persists. It was noted that the cryostat is a relatively old design and the pressure sensor itself is attached to it with an all metal connection. The current idea is that the sensor still picks-up noise that is conducted to the cryostat. The next time ALFOSC will be off the telescope this will be tested by simply removing the part containing the sensor. If this improves things, the sensor could be installed again using a partly plastic connection.

In principle, the remaining problems with using the CCD control card for multi-window photometry program with the normal BIAS CCD control program have been solved. Unfortunately, the main issue seems now to be with using the new data acquisition computer (see below).