A New Digital Catalog of Galaxies and its Application for Testing Automated Galaxy Classification Methods

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Session 57 -- Galaxies III
Oral presentation, Thursday, January 13, 10:15-11:45, Salon IV Room (Crystal Gateway)

[57.02] A New Digital Catalog of Galaxies and its Application for Testing Automated Galaxy Classification Methods

Zsolt Frei and James E. Gunn (Department of Astrophysics, Princeton University)

The purpose of this talk is to describe a galaxy catalog we developed in order to test different methods which may be used to classify galaxies in a future automated system. Considering the recent development of automated observational techniques and the automated surveys currently planned (such as the Sloan Digital Sky Survey), the need for such a classification system is evident.

In the past 5 years about 150 nearby galaxies were observed at three different sites (Lowell Observatory, Palomar Observatory and Appache Point Observatory). All the observations were done using CCD imagers and at least 2, but mainly 3 different filters. Special care have been taken to select the galaxies in a way to cover all possible morphological types (both spirals and ellipticals) and all possible inclination angles. After flattening the frames we removed foreground stars from all the images and photometrically calibrated the data. The galaxies are very well resolved, therefore provide the best set to test our methods. After careful ``degradation'' of these images, we hope to be able to use them to test our techniques for higher redshift cases.

Following the short description of the observations I will discuss several aspects of constructing the catalog: the star--removal methods we used and the approach to calibration we prefered. I will present data obtained from the images and the possible applications of the data we are currently investigating in order to classify galaxies. In conclusion I will mention other ways the catalog could be used for astrophysical research.

Thursday program listing