Observational Techniques: Computer Notes

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Aims

The aim of this section of the course is to enable you to use simple computer programs to solve a variety of common astronomical tasks. In particular, how to read in and print out ASCII (text) data files, how to do calculations, how to make plots, and how to interact with astronomical data in FITS format.

We could do all of this in a wide variety of programming languages. I have (somewhat arbitrarily) decided to use Python for this course, because it seems to be gaining popularity fast for astronomical data handling, and because some of you will have encountered it at the ATNF course. Once you're familiar with one programming language, others will come much more easily.

Notes on the relative merits of different programming languages

Running Python

The first step is to get Python up and running. We've put Python (plus all relevant libraries) on the Stromlo Linux computers moron and maggot. These should be enough for everyone doing this course to use.

To use these machines from a SunRay terminal, do the following:

In an xterm window, type "xhost moron" (or maggot, if you prefer). This tells your terminal to accept windows generated on moron.
Now log in to moron (or maggot). The command is "ssh -Y -l username moron". Type your username in place of "username". You will be prompted for your password.
You can now run python, by typing "python" at the prompt.
To run python interactively, including plotting, type "ipython -pylab". ipython is slightly nicer interactive version of python: "-pylab" tells it to import the matplotlib plotting package.
To get out of python or ipython, hold down the control button while pressing "D".
You can create programs using any text editor. There is one you can start up from the toolbar at the bottom of your screen. Alternatively type "emacs &" in the xterm window and an emacs editor window will appear.
When you've finished with moron (or maggot) type logout in the terminal window.

You might prefer to run the rograms on your own laptop. Versions of Python run on Windows, Macs, Unix and LINUX (among others) so you should be able to install it just about anywhere.

In addition to python itself, to do this course you will need some extra packages:

One easy way to get all of these (along with much much more) is the SciSoft package put together by ESO: http://www.eso.org/science/scisoft/. Alternatively you can install them individually.