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The Astrophysical Journal


The American Astronomical Society


A numerical algorithm has been developed for calculating three-dimensional visual interstellar extinction and its error from inputs of Galactic longitude, Galactic latitude, and distance. The code sythesizes the results of several published studies and can be used both for making correction to individual observations and for correcting statisticlal samples. The studies have been modified to introduce a statistical extinction correction at large (poorly-sampled) distances, and to truncate values at the (assumed) edge of the Milky Way. When combined, the studies allow individual absorbing clouds in the interstellar medium to be indentified within 5 kpc. Several observational selection biases are noted and discussed in view of this combined analysis. The FORTRAN-coded algorithm EXCTINCT FOR (v. 2.0.2.) can be obtained via anonymous ftp from site (c) 1997 American Astronomical Society. [S0004-6256(97)03611-X]