Program: GN-2010B-SV-146

We seek to measure the 12CO/13CO isotopic ratio in the currently transiting, enormous dark 550K disk in the system epsilon Aurigae, using GNIRS in high resolution, K band mode, in order to: (1) confirm prior detection during the 1984 eclipse, (2) measure the isotopic ratio in order to validate the low value (~10) reported then, and (3) use line series to more precisely gauge the excitation temperature of the CO in the gaseous portion of the dark, dusty disk. It is important to note that this is a rare opportunity and relatively TIME CRITICAL observation during GNIRS SV phase, as the current total eclipse phase lasts only until summer 2011 (repeats on a 27 year cycle). GNIRS data in combination with ongoing multi-telescope other data will significantly augment the overall campaign results.