Size and Morphology of Galaxies in the HST Medium Deep Survey

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Session 54 -- HST Medium Deep Survey
Display presentation, Tuesday, 10, 1995, 9:20am - 6:30pm

[54.04] Size and Morphology of Galaxies in the HST Medium Deep Survey

K. U. Ratnatunga, S. Casertano, R. E. Griffiths, M. Im, L. W. Neuschaefer (Johns Hopkins University), E. J. Ostrander (Arizona State University)

A modeling approach based on the maximum likelihood has been used to extract quantitative morphological and structural parameter estimates for over 15,000 faint galaxy images observed with the Hubble Space Telescope (HST) Wide Field Camera. Because convolved galaxy images are compared directly with the observations, we avoid the need for deconvolution, which is difficult and potentially unstable for faint images. Direct comparison of structural parameters measured from WFC and WFPC2 observations of the same objects in fields observed by both instruments show results that are consistent within the nominal errors derived in the procedure itself. The procedure successfully measures the parameters of faint galaxies, despite the potential difficulties related to the aberration in WF/PC and to the undersampling in WFPC2.' We illustrate the procedure as applied to process both WF/PC and WFPC2 data and present results from the HST Medium Deep Survey galaxy catalog which has now been made available through the HST archive.

This work was supported by NASA/HST grants GO-2684-0*-94A from STScI, which is operated by AURA, Inc., under NASA contract NAS5-26555.

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