EMSAO: Radial Velocities from Emission Lines in Spectra

Douglas J. Mink and William F. Wyatt
Harvard-Smithsonian Center for Astrophysics

Abstract

Many extragalactic objects for which radial velocities are desired display strong emission lines. For large surveys, the interactive determination of line centers and calculation of redshifts is too slow. The EMSAO task of the RVSAO IRAF package automatically finds emission lines, fits them with single or multiple Gaussians, and combines the determined redshifts weighting them by the uncertainty in the line centers. In addition to being used in the CfA and other redshift surveys, EMSAO has been used to study sky line shifts in 15 years of observations to characterize the uncertainty in instrumental measurements. RVSAO can be obtained via anonymous FTP from cfa-ftp.harvard.edu in the pub/iraf directory or through the World Wide Web at URL "http://tdc-www.harvard.edu/iraf/rvsao/rvsao.html".

Presented at the Fourth Annual Conference on Astronomical Data Analysis Software and Systems (ADASS 94) in Baltimore, Maryland September 1994.

Published in Astronomical Data Analysis Software and Systems IV, ASP Conf. Ser., Vol. 77, eds. R.A> Shaw, H.E. Payne, and J.J.E. Hayes, p. 496-499 (1995).

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