Abstract:

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 the cluster to be E(B-V)=0.39+/-0.02 [E(V-I)=0.53+/-0.03]. The metal 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 the RR Lyrae variables found in the cluster is 18.14+/-0.02 (based on a paper 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 methodology of Harris et al., we found that NGC 6426 is marginally older than M92 (by ~=0.7 Gyr). Following the Chaboyer, Demarque, & Sarajedini method we found NGC 6426 to have the same age as the mean metal-poor globular cluster of the galactic halo.

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