  Using the ground-based V and I photometry of a sample of stars from the Groth
Strip, we obtain the first empirical calibration of the F606W and F814W Hubble
Space Telescope WFPC2 filters for 0.5<V-I<4.5. We present results in the form
of corrections that need to be applied to the two synthetic calibrations
currently in use. Both calibrations are found to require corrections to zero
points and color-terms.
