The eclipse occurring during July 11, 1991 passes directly over the Mauna Loa Solar Observatory, Hawaii. This permits the rare opportunity to obtain a direct cross-calibration between the High Altitude Observatory (HAO) K-coronameter, located on Mauna Loa, and the HAO coronal camera, alleviating many of the uncertainties which have compromised comparisons in the past. The eclipse will permit the solar corona to be measured simultaneously by both instruments under identical viewing conditions, thus permitting a measure of the stray light, and a more accurate absolute calibration of the K-coronameter then previously attainable. The high altitude observing site, favorable meteorological conditions and the eclipse characteristics all promise a high probability of successful observations by both instruments. Recent laboratory calibrations of the photometric standards used by these instruments suggest that a significantly improved absolute determination of the coronal brightness, polarization- brightness product, and resultant electron density will be possible.
