Selections of Triangulum member stars. The gray dots represent rejected stars and the red dots represent the selected stars during each step. The member candidates identified by Martin et al. (2013) are marked by the green points. Top panel: local region of the overdensity in PM space, where the ellipse is defined to select member candidates in this step. Middle panel: stars in δ − V_r plane, where the error bars represent three times the uncertainties of V_r, and the red line is a linear fit to the stream sequence. Bottom panel: those candidates in a CMD.