Detector

The so-called ``reset level'' is the count level of the pre-integration readout of the array. It is supposed to be a function of detector temperature. When commissioning the array, it was adjusted to an optimal level, i.e. a level that maximises the dynamical range and minimises bad pixels. Over the years we have experienced various jumps in this level, needing a re-adjustment of the dc-offset voltages each time.

An extensive data set has been accumulated running a Cron job that monitors the reset level every hour when NOTCam is off telescope. Since monitoring accumulates 1 GB of data every day, a script was made to analyse the images and delete the images at once. Analysis of the data do show a relation with temperature, but the relation shows occasional jumps in zero-point, and changes in slope. The data sets needs to be analysed more in detail to search for the cause of this lack of stability, but the conclusion might be that no fixed value can be used, and this simply needs to be checked and adjusted when necessary.