Near-infrared observations of Cepheids : the distance to M 33.

Random-phase 1.65-micron observations of 15 Cepheids in M33, obtained using the NASA IRTF, the 5-m Hale telescope, the Canada-France-Hawaii telescope, and the MMT during 1980-1983 are reported and analyzed to estimate the distance to M33. The data are presented in tables and graphs and fitted to an IR period/luminosity relation for the Galaxy and the Magellanic Clouds. The M33 distance modulus is given as 24.5 + or - 0.2 mag, or 24.3 + or - 0.2 mag with a reddening correction based on the blue-band data of Sandage (1983).