Editing background data

Background measurements on blank sky are made to calibrate a visibility amplitude bias due to incoherent photons. Background scans are automatically loaded with the get_data procedure, but can be manually loaded, for example after computing the biases when the background has been zeroed before, using the following procedure.


Backgroundtable created.
Background data loaded.

Then use Reduce|BGData|PLOT to plot BGRate for all channels of the two spectrometers. The first one looks like this:

Note that there are almost no counts in channel 11, which is due to a HeNe laser notch filter. We flag these data manually (just plot channel 11 and then use Util|Edit to flag; re-plot to check whether all the data has been flagged); when OYSTER averages point data, any data without valid background scans will be discarded.