The age of NGC 6426, a metal-poor globular cluster in the galactic halo

We present B, V, R, and I photometry of the metal-poor globular cluster in the galactic halo, NGC 6426. The observations were performed using the 1.3 m Telescope at Skinakas Observatory in Crete. We derived the reddening of t he cluster to be E(B - V)= 0.39 +/- 0.02 [E(V - I) = 0.53 +/- 0.03]. The me tal abundance of the cluster was estimated from the shape of the red giant branch following the techniques by Sarajedini and by Da Costa & Armandroff. It was found to be [Fe/H] = -2.33 +/- 0.15 dex. The mean V magnitude of th e RR Lyrae variables found in the cluster is 18.14 +/- 0.02 (based on a pap er in preparation). The resulting distance modulus of the cluster is 16.41 +/- 0.07. Finally, we derived the relative age of NGC 6426. Using the metho dology of Harris et al., we found that NGC 6426 is marginally older than M9 2 (by similar or equal to 0.7 Gyr). Following the Chaboyer, Demarque, & Sar ajedini method we found NGC 6426 to have the same age as the mean metal-poo r globular cluster of the galactic halo.