Extinction-corrected (V ₀, I ₀) CMD (Section 2.2) for all stars in the NE shelf fields (Table 1), including stars without successful radial velocity measurements (gray points), MW foreground stars (black crosses; Section 3.1), and M31 RGB stars (red circles). The median photometric uncertainties as a function of magnitude are shown as black error bars on the left. For reference, we show PARSEC isochrones (black lines; Marigo et al. 2017), assuming 12 Gyr ages and [α/Fe] = 0, with [Fe/H] = −2.0, −1.0, −0.5, and 0 (from left to right).