Startup
To start the longslit pipeline, from an IDL prompt type:
...
The "blue" flat provides suitable counts in the blue half but saturates the red end of the spectrum. This is taken at higher lamp voltage (i.e. hotter,we use 2.2 V).
Enter in file names for each of these; if you only have one flat then put the same name in both fields and it will be fine. The software simply combines the two 2D frames, using a smooth weighting function to transition from one frame to the other without discontinuities.
Preferences
Once your file names are entered in, you will probably want to set preferences for the reduction stages. To do this, select the "Options->Preferences" pane from the menu bar. This will realize the following window: