Urania

NOTE: I will assume you have installed teTeX (a modern LaTeX package) in one of a variety of ways. Personally I recommend either Fink or MacPorts. However you can get a lot more information about this by visiting the “Getting Started” page at the Mac TeX website.

AASTeX is used to help typeset publications for all the major astronomical journals (at least in the US). You have two fundamental options for installing AASTeX on the Mac:

1. Single User Install: The easiest way is to download AASTeX (the version for LaTeX 2e) from http://www.journals.uchicago.edu/AAS/AASTeX/ and then just copy the aastex.cls file to whatever directory contains your latex source code for your paper. It should work just fine if you do that.
2. Global Install: If you want to make the AASTeX class file available to all your Mac users, you need to install it globally where the laTeX installation keeps its latex libraries. The easiest way to do this is to first determine where teTeX keeps its laTeX libraries (referred to as TEXMFMAIN). One simple way to do this is to type the following from the command line
   

   texconfig conf | grep TEXMFMAIN

   
   Once you have found that directory, edit the Makefile that comes with AASTeX so that INSTALLDIR equals that directory and fire off a
   

   sudo make install

   
   Once you have installed AASTeX, run
   

   sudo texconfig rehash

   
   And you should be set.

P.S. - Most teTeX installs come set to European paper sizes. If you want US Letter size, just run the configuration program and set US Letter size pages as the default using:

sudo texconfig