Monday 15 October at 3:30pm

ABSTRACT: "We present results from a program to use optical and near-IR surface brightness fluctuations (SBFs) to measure distances and stellar populations of elliptical galaxies. SBFs are appealing as a cosmological distance indicator because they have a well-understood physical basis. Employing a newly developed calibration, we have used the Keck Telescope to extend IR SBFs to much greater distances in order to accurately measure the Hubble Constant. In addition, SBFs provide information about stellar populations unobtainable from ordinary integrated light and spectra. Thus, they provide a means to break the age/metallicity degeneracy which plagues studies of the integrated light from galaxies. We have developed a set of stellar populations models optimized for SBF predictions. We use these to place novel constraints on the star formation histories of nearby cluster ellipticals. We find a significant range in the age of the population, as well as evidence that the lower mass galaxies have had more extended and heterogeneous star formation histories."