A hot pixel map is an image of so-called hot pixels in the CCD detector.
Hot pixels are pixels which indicate high values despite not being
illuminated. These pixels are detected in bias images because biases
have an exposure time of 0 seconds; they are not illuminated. In Astro-WISE the
HotPixelMap is derived from the BiasFrame. Hot pixels destroy
the value of all pixels behind the broken pixel as charge is moved through
it during the read-out process of the CCD. The result is a bad
column (see figure ).
The HotPixelMap is a mask image: good pixels have a value of 1 and bad pixels a value of 0.
To derive a HotPixelMap, type in the following at the AWE prompt:
awe> # Example using distributed processing (all CCDs simultaneously) awe> dpu.run('HotPixels', i='OMEGACAM', d='2014-04-28', C=1)or
awe> # Example using a Task (single CCD) awe> task = HotPixelsTask(instrument='OMEGACAM', date='2014-04-28', chip='ESO_CCD_#77', commit=1) awe> task.execute()