Chromospheric activity ﹩\mathrm{log}{R}_{\mathrm{HK}}^{{\prime} }﹩ index as a function of B − V color for our template stars (black), compared with the large field samples of Duncan et al. (1991), Wright et al. (2004), and Isaacson & Fischer (2010), (gray) computed with the procedure outlined in Mittag et al. (2013). Stars classified as “inactive” are marked with black squares, stars classified as “active” are marked with black circles. The outliers at low activity are giants, including G giant HD 5857, and the K giants Gl 705, HD 6497 and HD 145742 (see Table 1 for stellar properties).