Basic Information on velfit

Task: velfit
Purpose: Fit a theoretical velocity pattern to isovelocity image.
Categories: image analysis

        VELFIT fits a theoretical velocity pattern to a MIRIAD
        isovelocity image, weighted by the intensity image and a
        geometric factor specified by model input paramaters.
        The default option is to fit a rotation curve to an isovelocity
        image of a rotating disk.  The rotation curve and rms for the
        fit are printed out and can be used to find the best fit to the
        other parameters.  For more details see paper by Warner, Wright
        and Baldwin, 1973, MNRAS, 163,163.

Key: in
        The input image names, separated by commas.  The first image is
        the (x,y) intensity distribution integrated over the z-axis,
        e.g. velocity-integrated image.  The second image is an (x,y)
        model for the z-values, e.g. a mean velocity image.
        No default for either.

Key: region
        Region of image to be used in the fit.  See documentation on
        region for details.  Only the bounding box is supported.
        The default region is the entire image.

Key: center
        The center of the annuli in arcsec from the center pixel,
        measured in the directions of RA and DEC.
        Default: mapcenter as defined by crpix.

Key: pa
        Position angle of ellipse major axis in degrees.
        Default is 0 (north).

Key: incline
        Inclination angle in degrees.
        Default=0 (face on).

Key: radius
        Inner and outer radii and step size along major axis in arcsecs.
        The default is the whole image in steps equal to the pixel size.

Key: vsys
        Center value z-axis.  E.g. systemic velocity for rotation curve.
        Default: 0

Key: frang
        Free angle around the minor axis of points to ignore.  The total
        angle will be 2*frang.  (1/cos(theta) problem)
        Default: 0

Key: log
        The output log file.  The default is the terminal.

Key: options
        None yet.  Reserved for alternative models.
 
Revision: 1.4, 2013/08/30 01:49:21 UTC