Task: convol Purpose: Convolve a cube with a "beam function" Categories: map manipulation, map analysis CONVOL is a MIRIAD task which convolves a map or model with a "beam".WARNING:Convol does not do a very good job with masked images. Key: map The input image. This can be two or three dimensional. No default. Key: beam The input beam. This cannot be 3-dimensional. The beam is generally assumed to be symmetrical about its reference pixel, but see the "asymmetric" option if this is not so. If this is not given, then a Gaussian beam must be specified by the fwhm and pa parameters. Key: fwhm This parameter is ignored if the "beam" keyword is given. Otherwise, it specifies the width of the Gaussian convolving function unless options=final, in which case it specifies the required resolution of the output image. The size, in arcsec, will normally be two numbers giving the full-width at half- maximum of the major and minor axes of the Gaussian. At least one number must be given. If only one is given, the Gaussian will have equal axes. Key: pa This parameter is ignored if the "beam" keyword is given. Otherwise, it specifies the position angle of the Gaussian convolving function, unless options=final, in which case it specifies the required position angle of the effective beam of the output image. It is measured north through towards east, in degrees. Default 0. Key: region The region of the input map to convolve. See the Users Manual for instructions on how to specify this. The default is the entire input image. Key: out The output image. No default. Key: options Some extra processing options. Several can be given, separated by commas. Minimum match is used. "final" When parameters are given by the FWHM and PA keywords, the "final" option causes CONVOL to interpret these as the resolution required for the final output image. "divide" Divide, rather than multiply, the transform of the map by the transform of the beam. That is, perform deconvolution, rather than convolution. "asymmetric" Normally the beam is assumed to be symmetric (as it normally is in radio astronomy). This options causes CONVOL to go through the extra steps to handle a possibly asymmetric beam. If the beam is asymmetric, and you do not give this option, CONVOL symmetrises the beam (i.e. discards the anti- symmetric component). "correlate" Correlate rather than convolve with the beam. The difference between correlation and convolution are only apparent for asymmetric beams. "cube" Like final, but calculate required convolution for each plane separately. This option implies final. Use this to get the same beamsize in arcsec in all planes rather than the same beamsize in pixels. Warning: analysis tasks are likely to get source size and total flux wrong for the resulting cube. @ scale The scale factor to multiply the output by. The default is for CONVOL to determine the appropriate scale factor to make the output in JY/BEAM.NOTE:If the input image is in units of JY/BEAM, then to determine the appropriate scale factor, CONVOL must know the beam parameters (bmaj, bmin and bpa items) of both the input map and the beam. If these items are not present, CONVOL issues a warning and uses a scale factor of 1. Key: sigma When doing devonvolution (options=divide), this gives a noise parameter. Default is 0. Revision: 1.13, 2018/12/05 23:26:16 UTC

Generated by miriad@atnf.csiro.au on 06 Dec 2018