Values of Hβ and [MgFe]′ line-strength indices (top panel) and ⟨ Fe ⟩ and Mg _b line-strength indices (bottom panel) for the corotating (small red diamonds) and counter-rotating stellar component (small blue squares) measured along the major axis of NGC 1366 (r = −20.9″,−12.6″,11.4″, and 19.9″). The larger symbols correspond to the averaged line-strength indices for the two stellar components. The lines indicate the model predictions by Thomas et al. (2003) for different [α/ Fe] ratios (top panel) and ages (bottom panel).