Either install the latex which comes with ubuntu (if such a thing exists), or it can be found ​here.

Installation

cdelacruz@metis:/usr/local/iraf/extern$ sudo apt-get install tetex-bin tetex-doc 
psutils texi2html perl-tk tetex-extra xpdf-reader chktex lacheck rubber

= Supplemental Packages =

auctex - An integrated environment for writing TeX/LaTeX documents
preview-latex - render LaTeX environments within emacs

sudo apt-get install auctex preview-latex