The log T_eff versus log L (left panel) and log T_eff versus logg (right panel) plots display PAGB stars that have been observed in GCs. The red asterisk indicates the newly discovered PAGB star in E3, and the blue asterisks indicate PAGB stars found in other GCs. In the upper left panel, the H-burning PAGB evolutionary tracks of Miller Bertolami (2016) and Moehler et al. (2019) with metallicity Z = 0.001 are shown as dashed and solid lines, respectively, and for different initial and HB masses (as shown in the legend at right). The PAGB tracks of Moehler et al. (2019) consider an initial mass of 0.85 M_⊙ for all the evolutionary tracks. The lower left panel shows the post-RGB He-burning evolutionary tracks from Bloecker (1995) (green dotted line), Lei et al. (2015) (red dotted line), and Driebe et al. (1998) (black dotted line). The grey shaded region indicates a T_eff range of 16 000–19 000 K. The current mass for each evolutionary track at ∼18 000 K is shown with an arrow of the same colour and style as the evolutionary track. In the right panel, PAGB stars are shown on the log T_eff versus logg plane. The inset shows the zoomed-in view around the newly identified PAGB star.