  Photometric calibration to 5% accuracy is frequently needed at arbitrary
celestial locations; however, existing all-sky astronomical catalogs do not
reach this accuracy and time consuming photometric calibration procedures are
required. I fit the Hipparcos B_T and V_T magnitudes along with the 2MASS J, H,
and K magnitudes of Tycho-2 catalog-stars with stellar spectral templates. From
the best fit spectral template derived for each star, I calculate the synthetic
SDSS griz magnitudes and constructed an all-sky catalog of griz magnitudes for
bright stars (V<12). Testing this method on SDSS photometric telescope
observations, I find that the photometric accuracy for a single star is usually
about 0.12, 0.12, 0.10 and 0.08 mag (1 sigma), for the g, r, i, and z-bands,
respectively. However, by using ~10 such stars, the typical errors per
calibrated field (systematic + statistical) can be reduced to about 0.04, 0.03,
0.02, and 0.02,mag, in the g, r, i, and z-bands, respectively. Therefore, in
cases for which several calibration stars can be observed in the field of view
of an instrument, accurate photometric calibration is possible.
