acm calibration procedures

Take acm bias and dark frames

When sky surface brightness measurements are to be made with the acm we must take bias and dark frames. Here are examples of how to obtain these.

# Take 5 acm bias frames    
% acm_bias_run 5
arg1 - number of bias images to take  

# Take 21 5-second acm dark frames    
% acm_dark_run 21 5  
arg1 - number of images to take  
arg2 - integration time (5, 10, 20) 

Taking large numbers of each type of calibration is not critical. The fixed bias pattern seems to be fairly constant, but the mean bias level floats around. A set 5 acm bias frames on any given night would be extremely useful for deriving the nightly mean level.