DIRECT Distances to Nearby Galaxies Using Detached Eclipsing Binaries and Cepheids. I. Variables in the Field M31B

We undertook a long term project, DIRECT, to obtain the direct distances totwo important galaxies in the cosmological distance ladder -- M31 and M33,using detached eclipsing binaries (DEBs) and Cepheids. While rare and difficultto detect, detached eclipsing binaries provide us with the potential todetermine these distances with an accuracy better than 5%. The massivephotometry obtained in order to detect DEBs provides us with good light curvesfor the Cepheid variables. These are essential to the parallel project toderive direct Baade-Wesselink distances to Cepheids in M31 and M33. For bothCepheids and eclipsing binaries the distance estimates will be free of anyintermediate steps. As a first step of the DIRECT project, between September 1996 and January1997 we have obtained 36 full nights on the Michigan-Dartmouth-MIT (MDM)1.3-meter telescope and 45 full/partial nights on the F. L. Whipple Observatory(FLWO) 1.2-meter telescope to search for detached eclipsing binaries and newCepheids in the M31 and the M33 galaxies. In this paper, first in the series,we present the catalog of variable stars, most of them newly detected, found inthe field M31B ($\alpha_{2000.0},\delta_{2000}=11.20\deg,41.59\deg$). We havefound 85 variable stars: 12 eclipsing binaries, 38 Cepheids and 35 otherperiodic, possible long period or non-periodic variables. The catalog ofvariables, as well as their photometry and finding charts, are available usingthe anonymous ftp service and the WWW.