Color cuts to identify M dwarfs in the 2MASS PSC. For the 26 ﹩\left|b\right|> 20^{\circ }﹩ fields, we select PSC sources with ﹩H-K_{s}> 0.2﹩ to exclude bluer earlier type stars. For the remaining eight calibration fields, we use the gray "two‐box" cut and an apparent magnitude cut (﹩K_{s}< 14.3﹩). These cuts are chosen to select nearby M dwarfs and to exclude reddened background objects and red giants (﹩J-H> 0.75﹩; Allen 1982). An ﹩A_{v}=1﹩ interstellar reddening vector derived from Cohen et al. (1981); Carpenter (2001) is show in red. Mean PSC colors for K5 and K7 dwarfs are shown with black circles and are shown for M dwarfs with blue (M0, M1, M2, etc.) and cyan (M0.5, M1.5, M2.5, etc.) circles. See § 2.1 for discussion (Cohen et al. 1981; Cutri et al. 2006; Kirkpatrick & McCarthy 1994).