Q1. I want to read some fits files, and however I try it by the documentations I could find online it does not work. In order to get a command such as "readfits" to work do I have to import a library somehow? Would you please let me know how I can read and Gaussian smooth my FITS files? Q2. Also whenever I exit the terminal I have to run the following commands in order to make the "IDL" command to be working. Is there any way to get it done without this procedure? ~$ source /usr/exelis/idl84/bin/idl_setup.bash ~$ idl A1. READFITS is an user written routine that part of NASA's astrolib. It does not come with IDL by default. You will need to download the astrolib library and include it in the IDL path. You find more information about how to mange the IDL path in the following article: http://www.exelisvis.com/Support/Help... A2. You can add "source /usr/exelis/idl84/bin/idl_setup.bash" to the file "~/.bashrc". If you do this, IDL setup script will be sourced every time you start a new terminal.