The number of dead pixels in the currently installed engineering grade array was found to have increased from 1% in the beginning of 2003 to nearly 5% at the end of 2003. These dead pixels are mainly located on one of the sides of the array, so they don't interfere with observations much. However, there is a clear tendency for the fraction of dead pixels to increase with the number of thermal cycles. During 2003 NOTCam had to be warmed-up and opened 6 times. We should carefully consider when to replace the current array by the science grade array, especially taking into account possible future thermal cycles. After the last opening the number of dead pixels was at slightly above 5%.
To improve the pumping efficiency mainly for NOTCam but also for all our instruments, some extra vacuum equipment was purchased. The main idea was to change from the existing 25mm diameter tubes to 40mm that should improve the performance of the pumping. Also purchased were two pressure sensors and a controller/display so it is possible to see the pressure both at the pump and inside the dewar being pumped, simultaneously. This will remove the guess work in knowing when to open the valve for a dewar with a unknown vacuum and make the procedure safer.
The procedures to test the array, and analyze and present the results on the web have now been fully implemented. See
These procedures will actually be very useful when we install the science array.