Direct distances to nearby galaxies using detached eclipsing binaries and cepheids. IV. Variables in the field M31D

We undertook a long-term project, DIRECT, to obtain the direct distances to two important galaxies in the cosmological distance ladder-M31 and M33-usi ng detached eclipsing binaries (DEBs) and Cepheids. While rare and difficul t to detect, DEBs provide us with the potential to determine these distance s with an accuracy better than 5%. The extensive photometry obtained in ord er to detect DEBs provides us with good light curves for the Cepheid variab les. These are essential to the parallel project to derive direct Baade-Wes selink distances to Cepheids in M31 and M33. For both Cepheids and eclipsin g binaries, the distance estimates will be free of any intermediate steps. As a first step in the DIRECT project, between 1996 September and 1997 Octo ber we obtained 95 full/partial nights on the F. L. Whipple Observatory 1.2 m telescope and 36 full nights on the Michigan-Dartmouth-MIT 1.3 m telesco pe to search for DEBs and new Cepheids in the M31 and M33 galaxies. In this paper, the fourth in the series, we present the catalog of variable stars, most of them newly detected, found in the field M31D [(alpha, delta) = (11 .degrees 03, 41.degrees 27), J2000.0]. We have found 71 variable stars: fiv e eclipsing binaries, 38 Cepheids, and 28 other periodic, possible long-per iod or nonperiodic variables. The catalog of variables, as well as their ph otometry and finding charts, is available via anonymous ftp and the World W ide Web. The complete set of the CCD frames is available upon request.