Content-type: text/html Manpage of linmos


Section: User Commands (1)
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linmos - Linear mosaicing of datacubes  




map combination  


LINMOS is a MIRIAD task that performs simple linear mosaicing of input cubes to produce a single output cube. If only one input cube is given, LINMOS essentially does primary beam correction on it. If the input cubes overlap, LINMOS combines the overlapping regions so as to minimize the rms error.

To determine the primary beam of the telescope, LINMOS first checks the map header for the presence of the "pbtype" and then "pbfwhm" parameters. If present, LINMOS assumes the primary beam is the given type. If these parameters are missing, LINMOS checks if the telescope is one that it knows. If so, then the known form for the primary beam is used. See task "pbplot" to check LINMOS's primary beam models.  


The names of the input cubes - many may be given. There is no default. Inputs should generally be on the same grid system. If not, linear interpolation is performed to regrid using the first image as the template. LINMOS's ability to do this is inferior to task REGRID. The intensity units of all the inputs, and the pixel size and alignment of the third dimension are assumed to be the same.
The name of the output cube. No default. The center and pixel size of the first input image is used as the grid system of the output.
RMS noise level in each of the input cubes. If not specified, the value is taken from the 'rms' item in the input image header if that is available, and if not, then the rms of the previous image is used. If no value could be determined for the first image, a warning is issued and ALL images are given equal weight by assigning an RMS of 1.0.
Bandwidth of the image in GHz. If specified the beam response will be averaged across the frequency band before being applied to the image. Use for wide band images to improve the accuracy of the correction.
Extra processing options. Several can be given, separated by commas. Minimum match is supported. Possible values are:
  taper        By default, LINMOS fully corrects for primary
               beam attenutation.  This can cause excessive
               noise amplification at the edge of the mosaiced
               field.  The `taper' option aims at achieving
               approximately uniform noise across the image.
               This prevents full primary beam correction at the
               edge of the mosaic.  See Eq. (2) in Sault,
               Staveley-Smith and Brouw (1996), A&AS, 120, 375,
               or use "options=gains" to see the form of the
  sensitivity  Rather than a mosaiced image, produce an image
               giving the RMS noise across the field.  This is
               dependent on the RMS specified, either as an
               input parameter or else as a header item (see
  gain         Rather than a mosaiced image, produce an image
               giving the effective gain across the field.  If
               options=taper is used, this will be a smooth
               function.  Otherwise it will be 1 or 0 (blanked).
nmos.for,v 1.3 2011/06/10 12:03:56 pteuben Exp $




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