The System of Alpha Coronae Borealis.

A photoelectric light-curve at X 7230 has been obtained for a Coronae Borealis. The secondary minimum was located, and its depth, width, and phase have been measured. Orbital and physical elements have been derived, both relative and absolute. The was analyzed after correction of it for the distorting effect of the rotation of the primary component; likewise, an assumption that the secondary component also has appreciable axial rotation was found to be necessary. The absolute elements were derived by means of a special application of the mass-luminosity law, and an attempt was made to estimate the uncertainty of the absolute elements. It is concluded that observationally determined darkening coefficients in red light may be significantly smaller than predicted by theory and that a Coronae Borealis is appreciably brighter for its mass than Sirius.