(a) DES color–magnitude diagram of Tucana III. Stars within 18′ of the center of Tuc III are plotted as small black dots and stars selected for spectroscopy (as described in Section 2.2) are plotted as filled gray circles. Points surrounded by black outlines represent the stars for which we obtained successful velocity measurements and those we identify as Tuc III members are filled in with red. The M92 sequence and PARSEC isochrone used to define the RGB of Tuc III are displayed as blue and red curves, respectively. (b) Spatial distribution of the observed stars. Symbols are as in panel (a). The arrow at the bottom illustrates the direction of the tidal tails identified by Drlica-Wagner et al. (2015b). These tidal tails make it difficult to determine the ellipticity of Tuc III with existing data, so we represent the half-light radius of Tuc III with a black circle. (c) Radial velocity distribution of observed stars. The clear narrow peak of stars at ﹩{v}_{\mathrm{hel}}\sim -100﹩ ﹩\mathrm{km}\,{{\rm{s}}}^{-1}﹩ highlighted in red is the signature of Tuc III. The hatched histogram indicates stars that are not members of Tuc III.