Stellar evolutionary isochrones superimposed over the CMD for our 65 kpc field against absolute magnitude M_I and (V − I)₀ color. The models assume RGB stars of age 12 Gyr. Solid black lines are the α-enhanced isochrones from Pietrinferni et al. (2004, 2006); from left to right, the metallicities are [M/H] = −2.27, −1.79, −1.49, −1.27, −0.96, −0.66, −0.35, −0.25, 0.06. The dashed blue line marks [M/H]=−0.7, the cut at which we divide between metal-poor and metal-rich objects. The TRGB begins at M_I = −4.05 (Rizzi et al. 2007).