"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.