Preliminary Design Report April 13, 2009 Version 3 Authors Nathaniel R. Butler (Astronomy Dept., UC Berkeley; nat@astro.berkeley.edu; +1-510-642-4223), Joshua S. Bloom (UC Berkeley), Alejandro Farah (IA-UNAM), Julien Girard (ESFM-IPN), Jesus Gonz´ alez (IA-UNAM), Alexander Kutyrev (Goddard), William Lee (IA-UNAM), J. Xavier Prochaska (UCO/Lick), Enrico Ram´ ırez-Ruiz (UC Santa Cruz), Michael Richer (IA-UNAM), Alan Watson (CRyAUNAM, IA-UNAM)