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In case any of you are currently looking at the webcam images, you'll see John & Lindsey taking 'calibration' images in the dome ...

In order to obtain 'photometric quality' images with the CCD camera,certain calibrations need to be performed.

These include 

1. subtracting the 'bias level'  -- i.e. removing the offset signal introduced by the electronics to stop the pixel values in the images going negative due to random (noise) fluctuations.

2. Subtracting the 'dark current' -- i.e. removing the electronic noise in the CCD images

3. Dividing by the 'flat-field' -- i.e. the response of the CCD to a uniformly illuminated scene.

John and Lindsey are currently acquiring bias images, dark images and flat field images to use on the later data we will take. Later I'll show  you these calibration  images and the  effect of using them on the data.

Andy