Content-type: text/html Manpage of ellint


Section: User Commands (1)
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ellint - Integrate a Miriad image in elliptical annuli.  




image analysis  


ELLINT integrates a Miriad image in elliptical annuli in the first two dimensions. E.g. to find the radial brightness distribution, or flux density as a function of distance in a galaxy. The integration is done separately for each image plane in the region included.

The output consists of 6 columns. They are the

outer radius (arcsec) of the annulus; number of pixels in the annulus; the average (median) in the annulus; the rms of the annulus; the sum in the annulus normalized by the volume of the primary beam

   (if there is one);
the cumulative sum for all annuli so far.  


Input image name. xyz images only. No default.
Optional output image containing the residuals from the average values in each annulus. By default this image is not created. See also options=spline to get better results for noise free images.
Region of image to be integrated. E.g.
  % ellint region=relpix,box(-4,-4,5,5)(1,2)
integrates the center 10 x 10 pixels for image planes 1 and 2. Unmasked pixels within the bounding box are selected. The default region is the entire image.
The offset of the center of the annuli in arcsec from the reference pixel, measured in the directions of RA and DEC.
Position angle of ellipse major axis in degrees. Default is 0 (north). PA is measured in the usual sense, N through E (counter clockwise).
The ellipse is assumed to be a circular structure that appears elliptical because it is viewed at some inclination. The "incline" parameter gives this inclination angle in degrees. Default=0. (face on)
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. Warning: for images where the center is not in the center you may want to explicitly specify this keyword, to avoid missing data.
If you request that the fluxes be corrected for the primary beam (see OPTIONS), ELLINT will normally construct a primary beam type using information from the dataset. However you can override this with a primary beam type of your own choosing. The primary beam type can either be a telescope name whose primary beam is known (e.g. hatcreek, vla, atca, etc) or you can select a Gaussian form with "gaus(xxx)". Here xxx is the primary beam FWHM in arcseconds. For example gaus(120) is a telescope with a 120 arcsec primary beam.
Scale factor applied to the amplitudes before printing them. Default=1.
Task enrichment options. Minimum match is active.
  pbcorr    This causes the images to be corrected for primary beam
            attenutation before integrating.
  median    Find the median of each annulus instead of the average.
  mode      Find the mode of each annulus instead of the average.
  natural   Assume keywords "center" and "radius" are in natural
            units rather than arcsec.
  table     Output ring data in logfile. No fitting done. Logfile
            now contains coordinates w.r.t. the reference pixel 
            (in arcsec), the image value, and the radius in the disk
            defined by PA and INCLINE.
  spline    use a spline fit unstead of a step function to estimate
            the intensity at any radius for residual images
Smoothing option of radial profile when option=median is used in residual map computation. These are the number of pixels added before and after the ring. Default: 0
The output log file. The default is the terminal.




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Time: 18:35:38 GMT, July 05, 2011