AN IUE SURVEY OF INTERSTELLAR H-I LY(ALPHA) ABSORPTION .1. COLUMN DENSITIES

We measure Galactic interstellar neutral hydrogen column densities by analyzing archival interstellar Lyalpha absorption line data toward 55 4 B2 and hotter stars observed at high resolution with the IUE satelli te. This study more than doubles the number of lines of sight with mea sures of N(H I) based on Lyalpha. We have included the scattered light background correction algorithm of Bianchi and Bohlin in our data red uction. We use the correlation between the Balmer discontinuity [c1] i ndex and the stellar Lyalpha absorption in order to assess the effects of stellar Lyalpha contamination. Approximately 40% of the B stars wi th measured [c1] index, exhibit serious stellar Lyalpha contamination. Table 1 contains the derived values of the interstellar N(H I) for 39 3 stars with at most small amounts of stellar contamination. Table 2 l ists the observed values of total N(H I) for 161 stars with suspected stellar Lyalpha contamination and/or uncertain stellar parameters.