The age of the Small Magellanic Cloud globular cluster NGC 411

The age of the SMC red globular cluster NGC 411 is estimated as 1.5 ± 0.5 Gyr from a C-M diagram that reaches below the cluster main-sequence turnoff. The accuracy of this estimate is limited primarily by uncertainty in the distance modulus of the cluster: at (m - M)0 = 18.8, the age is 1.8 ± 0.3 Gyr, while at (m-M)0 = 19.3 it is 1.2 ± 0.3 Gyr. For these latter results the uncertainty stems primarily from uncertainty in the extent to which convective overshoot affects the theoretical isochrones used for the age determination and, to a lesser extent, from uncertainty in the cluster metal abundance which is estimated as [Fe/H] = -0.9 ± 0.3 dex. For the SMC field in the vicinity of the cluster, zero-age main-sequence fits strongly support the adoption of the smaller (18.8) modulus.