Dewar

It was realized that the holding time of the modified dewar with the new CCD controller would be significantly shorted than before. Analysis of the dewar temperature over the first two months showed the holding time to be 15-18 hours, i.e., it is needed to refill the dewar twice a day. One problem is that the data from the temperature sensors is not included in the new controller so the dewar temperature is not under computer control and the temperature can only be obtained be looking at the sensor display itself. This means we can not use an automated temperature control which, given the rather short holding time, increases the risk of an accidental heating up of the CCD.