The Discovery of Two New Cepheid Variables in M101
Session 17 -- Normal Galaxies
Oral presentation, Monday, 10:30-12:00, Wheeler Room

## [17.06] The Discovery of Two New Cepheid Variables in M101

J. G. Cohen (Palomar Observatory)

The Four Shooter Consortium was organized in 1985 to search for Cepheid variables in M101 using the 200$-$inch Hale telescope. We report the discovery of two new Cepheid variables, the first with a period of 36 days and a mean magnitude in the Thuan-Gunn g color of 24.09 mag, while the second has a period of 100 days with a mean g magnitude of 22.48. There are approximately 15 other stars that are definitely variable in this magnitude range, but periods could not be determined for them. These magnitudes are transformed in a preliminary way to V, and these data are combined with the two variables previously found by Cook, Aaronson, and Illingworth (1986, Ap.J. 301, L45). We derive an apparent distance modulus to M101 of 29.4 $\pm{0.15}$ mag.

I am grateful to all of the many Palomar observers who contributed Four Shooter frames to this project.