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.

get_bgdata

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.

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