The ALFOSC CCD was noted to have a higher RON than before. After an extensive investigation it was found that the noise is caused by the pressure sensor. Disconnecting the sensor lowers the noise to levels even lower than before the recent rise, now being comparable to levels measure in the lab.
An upgrade version was made of the multi-window photometry program to do polarimetry. The program was successfully commissioned and used in an observing run.
A plan has been defined to solve the remaining problems with using the CCD control card with the normal BIAS CCD control program, but this depends primarily on Roy Østensen. He is leaving La Palma soon, but he is going to work in Leuven (Belgium) and he is expected to regular come back to La Palma (in connection with Mercator).
The possibility to readout the CCD using both amplifiers (basically gaining a factor 2 in readout speed) has been investigated. The tests indicate that the data can be reduce properly and provide reliable results. However, the data provided by the CCD controller requires some manipulation of the data before it can be reduced and the current post-processing system can not provide the data in proper MEF format when the CCD is windowed or binned.
Thomas Augusteijn 2006-05-08