You can find the full lecture on this material at http://spiff.rit.edu/classes/phys374/gnuplot/gnuplot.html You will need to use the username "modern" and the password discussed in lecture today to access the web page and to download the datafile mentioned in problem 2 below. Please contact Michael Richmond if you are unable to access these materials.
You will often need to create graphs to illustrate your measurements, and show the degree to which they match predictions of some particular model. We recommend gnuplot as a tool for making graphs. It runs on all major platforms, it's free, it can create graphics good enough to publish, and it has some powerful features. It is already installed on the computers in the Mac OS side of the Gosnell Computer Lab, and on the computers in the Modern Physics Lab rooms. You can acquire a copy from
Professor Barton has written a brief guide to installing gnuplot under Windows.
If you want to install gnuplot under Mac OS X, I recommend the clever trick involving another analysis package which will make the installation very easy, and avoid all compiling.
Create a graph which shows a closeup of the weak absorption line in this datafile centered near 6547.7 Angstroms. Zoom in so that the data in this region cover your graph from left to right and from top to bottom.
Use your graph to estimate the central wavelength of this line, the approximate width of the line, and its approximate depth.