George Djorgovski was the previous option representative (see his website, where much of the material here originated).
The Option Rep serves as the academic advisor for graduate students on their first year, and 2nd year until they sign up with a thesis advisor; deals with all academic/student matters other than the thesis advising and research, and generally minds the academic store. Any Ay students are welcome any time to come and talk to me, especially if you have a problem.