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Astron. Astrophys. Suppl. Ser. 140, 247-260

On the automatic folding of optical rotation curves

D.F. Roscoe

Send offprint request: D.F. Roscoe

School of Mathematics, Sheffield University, Sheffield, S3 7RH, UK
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Received June 7; accepted September 6, 1999

Abstract:

Mathewson, Ford and Buchhorn (1992, MFB hereafter) published the unreduced data for the optical rotation curves of 967 southern sky spiral galaxies. Recognizing that accurate dynamical modelling of spiral galaxies required the availability of a large data-base of correspondingly accurately folded rotation curves, Persic & Salucci (1995, PS hereafter) undertook to fold the MFB sample in an appropriately meticulous way; of the 967 folded rotation curves, 900 were judged by PS to be of moderate to excellent quality, whilst 67 were judged to be of poor quality and of very limited use for dynamical studies. The folding process used by PS was a time-consuming and labour-intensive one in which the quality of each fold was judged "by eye''.

Subsequently, MFB (1996) published the unreduced optical rotation curves for approximately another 1100 southern sky spirals and, undoubtedly, more will follow from various sources. For this reason, and because of the importance of having large numbers of accurately folded rotation curves for dynamical studies, we have developed the automatic folding algorithm described herein.

An uncompiled Fortran program (using NAG routines) and data files are available via http://www.shef.ac.uk/~ap1dfr. Download the text file "ReadMe'' and follow instructions.

Key words: methods: numerical -- galaxies: kinematics and dynamics