DIRECT Distances to Nearby Galaxies Using Detached Eclipsing Binaries and Cepheids. III. Variables in the Field M31C

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, DEBs provide us with the potential to determine these distances withan accuracy better than 5%. The extensive photometry obtained in order todetect DEBs provides us with good light curves for the Cepheid variables. Theseare essential to the parallel project to derive direct Baade-Wesselinkdistances to Cepheids in M31 and M33. For both Cepheids and eclipsing binaries,the distance estimates will be free of any intermediate steps. As a first step in the DIRECT project, between September 1996 and October1997 we obtained 95 full/partial nights on the F. L. Whipple Observatory 1.2 mtelescope and 36 full nights on the Michigan-Dartmouth-MIT 1.3 m telescope tosearch for DEBs and new Cepheids in the M31 and M33 galaxies. In this paper,third in the series, we present the catalog of variable stars, most of themnewly detected, found in the field M31C [(alpha,delta)=(11.10, 41.42) deg,J2000.0}]. We have found 115 variable stars: 12 eclipsing binaries, 35 Cepheidsand 68 other periodic, possible long period or non-periodic variables. Thecatalog of variables, as well as their photometry and finding charts, isavailable via anonymous ftp and the World Wide Web. The complete set of the CCDframes is available upon request.