Globular cluster colors and the cosecant law

All available integrated UBV colors and spectral types of globular clusters are analyzed to determine whether one can obtain the reddening from the integrated parameters. Reddening determinations by various authors for individual clusters, from field stars, comparison of color-magnitude diagrams, etc., are collected and made consistent with one another. Using these data, the intrinsic color-spectral type relationships for globular clusters in the galaxy are found to agree with those for M31, allowing for a reddening of M31 of E(B-V) = 0.08 plus or minus 0.04. The same color-spectral type relationships are found for early-type globular clusters by an analysis of the csc law of galactic absorption. From these determinations of the reddening, the presence of a hole in the dust layer in the vicinity of the sun is confirmed. Evaluation of the reddening for late-type clusters shows that the reddening slope X = E(U-B)/E(B-V) increases to approximately X = 0.85 for later spectral types.