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NRAO Home > CASA > CASA Cookbook and User Reference Manual |
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8.2.1.9 sdgrid
infiles -- name of input SD dataset. can be list.
example: ’testimage.asap’
[’testimage1.asap’,’testimage2.asap’]
antenna -- select data based on antenna name(s) or id(s)
default: -1
example: 0, ’DV01’
scanlist -- list of scan numbers to process
default: [] (use all scans)
example: [21,22,23,24]
ifno -- IFNO to be gridded
default: -1 (only process IFNO in the first row)
example: 1
pollist -- POLNO to be gridded
default: [] (all polarizations)
example: 1,[0,1]
gridfunction -- gridding function
options: ’BOX’ (Box-car), ’SF’ (Spheroidal),
’GAUSS’ (Gaussian), ’PB’ (Primary-beam)
default: ’BOX’
example: ’SF’
>>> gridfunction expandable parameter:
width -- width of convolution kernel, not available
for BOX gridding
default: -1 (use default for each gridfunction)
example: 3
weight -- weight type (both lower-case and upper-case are
acceptable)
options: ’UNIFORM’,
’TSYS’ (1/Tsys**2 weighted)
’TINT’ (integration time weighted)
’TINTSYS’ (Tint/Tsys**2)
default: ’UNIFORM’
clipminmax -- do min/max cliping if True
default: False
outfile -- output data name
default: ’’ (outfile will be set to infile+’.grid’)
example: ’mydata.asap.grid’
overwrite -- overwrite option for outfile
default: False (not overwrite)
options: True, False
example: if True, existing file will be overwritten
npix -- x and y image size in pixels, symmetric for single value
default: -1 (automatically calculated from cell size and
the data)
example: npix=200 (equivalent to [200,200])
cell -- x and y cell size. default unit arcsec
default: ’’ (automatically calculated from npix if it is
set, otherwise ’1.0arcmin’)
example: cell=[’0.2arcmin, 0.2arcmin’]
cell=’0.2arcmin’ (equivalent to example above)
cell=12.0 (interpreted as ’12.0arcsec’=’0.2arcmin’)
center -- grid center
default: ’’ (automatically calculated from the data)
example: ’J2000 13h44m00 -17d02m00’
[’05:34:48.2’, ’-05.22.17.7’] (in J2000 frame)
[1.46, -0.09] (interpreted as radian in J2000 frame)
plot -- Plot result or not
default: False (not plot)
example: if True, result will be plotted
DESCRIPTION:
The sdgrid task performs spatial gridding according to the user specification of spatial grid, convolution function, etc.
For grid configuration, the task supplements necessary information by referring input data if any of gridding parameter (’npix’, ’cell’, or ’center’) is not specified by the user. If ’center’ is default value (empty string), central position of the grid will be set to the center of observed area, i.e. x=0.5*(xmax+xmin), y=0.5*(ymax+ymin). If either ’cell’ or ’npix’ is set, unspecified one will be calculated from the others. In that case, total extent of the grid will be set to cover all observed position. If neither ’cell’ nor ’npix’ is set, cell size will be set to 1.0 arcmin and number of pixel will be calculated based on that cell size.
Currently, only J2000 frame is supported.
The parameter gridfunction sets gridding function for imaging. Currently, the task supports ’BOX’ (Box-car), ’SF’ (Prolate Spheroidal Wave Function), ’GAUSS’ (Gaussian). and ’PB’ (Primary Beam, not implemented yet). For ’PB’, correct antenna informations should be included in input file. The ’width’ parameter specifies width of the convolution kernel in pixel unit. For Gaussian gridding, ’width’ is treated as HWHM and actual width (the width that convolution function has non-zero value) is set to 4*HWHM to take into account contribution from Gaussian tail. Otherwise, ’width’ is treated as actual width of the convolution function.
Boolean parameter ’plot’ controls whether gridded result is plotted or not. If True, color map of gridded data will be shown. Pixel center and observed position are overlayed as blue dot and red dot, respectively. Currently, channel averaged value will be plotted.
More information about CASA may be found at the
CASA web page
Copyright © 2010 Associated Universities Inc., Washington, D.C.
This code is available under the terms of the GNU General Public Lincense
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