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Session 3 - Source Surveys, Galaxy Surveys, Distance Scale I.
Display session, Wednesday, January 07
It is well known that galaxy characteristics, such as morphology, surface brightness distribution, ellipticity, and concentration index change with bandpass, be it slowly or drastically. The rate depends on the relative importance of different physical processes, such as its (recent) star formation history and the distribution of gas and dust. As a consequence, for example, the K-correction to correct the observed fluxes of distant galaxies for bandpass shifting and wavelength stretching is strongly dependent on galaxy type and its star formation history plus dust content. To better understand the morphology and surface brightness (SB) profiles observed for the many faint galaxies seen in deep HST images out to large redshifts, similar corrections are needed for other galaxy parameters such as morphology, ellipticity and concentration index.
To quantify the changes of galaxy parameters with restframe wavelength (and redshift), we present a large systematic survey in UBVRIJHK of about 400 nearby galaxies of all inclinations, Hubble types, and colors. These galaxies come from samples imaged in (a subset of) the filters UBVRIJHK by deJong et al., by Frei et al., and by Frogel et al. (for Ohio State Survey). We present the first part of a large U band imaging project with the new high throughput wide field camera at the f/1 Vatican Advanced Technology Telescope on Mt Graham, AZ. The combined UBVRIJHK sample allows us to quantify local galaxy parameters in the range 3000 Å\mu. A modeling analysis applied to the faint field galaxies seen with HST will allow us to address the relative importance of bulge versus disk dominated galaxies, of late-type versus irregular galaxies, and of low SB galaxies versus sub-galactic clumps as a function of redshifts.
Program listing for Wednesday