The Hungarian-made Automated Telescope Network (HATnet) is an ongoing project to detect transiting extrasolar planets using small-aperture (11cm diameter) robotic telescopes. In this paper, we present the results from using image subtraction photometry to reduce a crowded stellar field observed with one of the HATnet telescopes (HAT-5). This field was chosen to overlap with the planned Kepler mission. We obtained I-band light curves for 98,000 objects in a 67 square degree field of view centered at J2000 ({alpha},{delta})=(19h44m00.0s, +37{deg}32'00.0"), near the Galactic plane in the constellations Cygnus and Lyra. These observations include 788 exposures of 5' length over 30-days. For the brightest stars (I~8.0) we achieved a precision of 3.5mmag, falling to 0.1mag at the faint end (I~14). From these light curves we identify 1617 variable stars, of which 1439 are newly discovered.

Cone search capability for table J/AJ/128/1761/table1 (HAT Catalog of "Kepler Field" Variables)