DIRECT DISTANCES TO NEARBY GALAXIES USING DETACHED ECLIPSING BINARIESAND CEPHEIDS - I - VARIABLES IN THE FIELD M31B

We have undertaken a long-term project, DIRECT, to obtain the direct d istances to two important galaxies in the cosmological distance ladder - M31 and M33 - using detached eclipsing binaries (DEBs) and Cepheids . While rare and difficult to detect. DEBs provide us with the potenti al to determine these distances with an accuracy better than 5%. The e xtensive photometry obtained in order to detect DEBs provides us with good light curves for the Cepheid variables. These are essential to th e parallel project to derive direct Baade-Wesselink distances to Cephe ids in M31 and M33. For both Cepheids and eclipsing binaries, the dist ance estimates will be free of any intermediate steps. As a first step in the DIRECT project, between 1996 September and 1997 January we obt ained 36 full nights on the Michigan-Dartmouth-MIT Observatory 1.3 m t elescope and 45 full/partial nights on the F. L. Whipple Observatory 1 .2 m telescope to search for DEBs and new Cepheids in the M31 and M33 galaxies. In this paper, first in a series, we present the catalog of variable stars, most of them newly detected, found in the field M31B [ (alpha, delta) = (11.degrees 20, 41.degrees 59), J2000.0]. We have fou nd 85 variable stars: 12 eclipsing binaries, 38 Cepheids, and 35 other periodic, possible long-period or nonperiodic variables. The catalog of variables, as well as their photometry and finding charts, is avail able via anonymous ftp and the World Wide Web.