PLOTT_BDA will make a light curve plot using either the index or
roadmap. The second `T' signifies that it is a time plotting routine.
Four plots are made on the page, one for each channel. Some sample calls are:
IDL> plott_bda, index
IDL> plott_bda, roadmap
IDL> plott_bda, roadmap(100:200), psym=10