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Observed integrated colors, spectral types, and E(B -V) color excesses for 50 Galactic globular clusters are used to calibrate the relationship between intrinsic UBVRI colors and integrated spectral types. Color excesses are then estimated from Reed s averages of observed (B -V) colors for 93 clusters with integrated spectral types on the Hesser and Shawl system. For seven clusters (NGC 6171, NGC 6287, NGC 6397, NGC 6402, NGC 6838, NGC 6934, and NGC 7099) differences between independently-derived E(B-V) values and our calculated values exceed 0.1 magnitude. We find that the R and I colors add little reddening information. Mean colors of five spectral-type groupings are presented. Clusters of the latest spectral type (i.e., most metal rich) are particularly easy to identify in the (U -V) 0 , (V -7) 0 diagram, whose usefulness as a metallicity probe appears comparable to that of, for instance, the (C -M) 0 ,(M -T x ) 0 diagram of the Washington system. Distributions of our inferred reddenings and intrinsic colors with Galactic longitude and latitude are presented. From a lese b I analysis in which E B _ V = a B _ v lese b I -he, we estimate a B _ v = 0.046 ± 0.004 mag, with values for the northern and southern Galactic hemispheres of 0.068 ± 0.006 and 0.039 ± 0.003, respectively; the values of c are not significantly different from zero.

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The overall problem of reducing photoelectric photometry data is reviewed, and a general reduction method that differs significantly from the traditional approach of Hardie and others is summarized and analyzed. The technique, essentially a multilinear solution for all the transformation model parameters simultaneously, is especially suitable for modern computing facilities, and is both faster and more reliable than older approaches. This particular technique is also shown to be sufficiently powerful and versatile that it gives the observer several important advantages and flexibilities at the telescope, and can be set up to apply to many general situations. Examples and comparisons of its use for single-and multiple-night reductions are presented, and the role of the reduction problem in the whole area of photoelectric photometry is discussed.

Corrected expressions for parameter variances in linear (straight-line) least-squares fits given in an earlier paper [B. C. Reed, Am. J. Phys. 57, 642–646 (1989)] are presented and discussed. In addition, some simplifications to the solution given in that paper are presented, and some comments made as to the role of weighting.