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We present BV photometry of the Galactic globular cluster NGC 6402 (M14),based on 65 V frames and 67 B frames, reaching two magnitudes below theturn-off level. This represents, to the best of our knowledge, the deepestcolor-magnitude diagram (CMD) of NGC 6402 available in the literature.Statistical decontamination of field stars as well as differential reddeningcorrections are performed in order to derive a precise ridgeline and derivephysical parameters of the cluster therefrom.  We discuss previous attempts to derive a reddening value for the cluster, andargue in favor of a value E(B-V) = 0.57 +/- 0.02, which is significantly higherthan indicated by either the Burstein & Heiles or Schlegel et al. (correctedaccording to Bonifacio et al.) interstellar dust maps. Differential reddeningacross the face of the cluster, which we find to be present at the level ofDelta E(B-V) ~ 0.17 mag, is taken into account in our analysis. We measureseveral metallicity indicators based on the position of the red giant branch(RGB) in the cluster CMD. These give a metallicity of [Fe/H] = -1.38 +/- 0.07in the Zinn & West scale and [Fe/H] = -1.28 +/- 0.08 in the new Carretta et al.(UVES) scale. We also provide measurements of other important photometricparameters for this cluster, including the position of the RGB luminosityfunction "bump" and the horizontal branch (HB) morphology. We compare the NGC6402 ridgeline with the one for NGC 5904 (M5) derived by Sandquist et al., andfind evidence that NGC 6402 and M5 have approximately the same age, to withinthe uncertainties -- although the possibility that M14 may be slighlty oldercannot be ruled out.

The Globular Cluster NGC 6402 (M14). I. A New BV Color-Magnitude Diagram