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0.1.109 sdgridold
Requires:
Synopsis
ASAP SD task [DEPRECATED]: SD gridding task
Description
### DEPRECATION WARNING
#################################################
This task will be removed in CASA 5.1. The functionality of this task with
MeasurementSet format is replicated with sdimaging.
#########################################################################
Task sdgridold 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.
Arguments
Inputs |
| ||
infiles |
| a list of names of input SD datasets
| |
| allowed: | any |
|
| Default: | variant ”” |
|
antenna |
| select an antenna name or ID, e.g. ’PM03’ (only effective
for MS input)
| |
| allowed: | any |
|
| Default: | variant -1 |
|
spw |
| select data by IF IDs (spectral windows), e.g. ’3,5,7’
(”=all)
| |
| allowed: | string |
|
| Default: | -1 |
|
scan |
| select data by scan numbers, e.g. ’21~23’ (”=all)
| |
| allowed: | string |
|
| Default: |
|
|
pol |
| select data by polarization IDs, e.g. ’0,1’ (”=all)
| |
| allowed: | string |
|
| Default: |
| |
gridfunction |
| gridding function for imaging
| |
| allowed: | string |
|
| Default: | BOX | |
convsupport |
| truncate of convolution kernel
| |
| allowed: | int | |
| Default: | -1 |
|
truncate |
| truncation radius of convolution kernel | |
| allowed: | any |
|
| Default: | variant -1 | |
gwidth |
| HWHM for gaussian
| |
| allowed: | any |
|
| Default: | variant -1 |
|
jwidth |
| c-parameter for jinc function
| |
| allowed: | any |
|
| Default: | variant -1 |
|
weight |
| weight type
| |
| allowed: | string |
|
| Default: | UNIFORM |
|
clipminmax |
| clip minimum and maximum values during gridding
| |
| allowed: | bool |
|
| Default: | False |
|
outfile |
| name of output file
| |
| allowed: | string |
|
| Default: |
|
|
overwrite |
| overwrite the output file if already exists [True, False]
| |
| allowed: | bool |
|
| Default: | False |
|
npix |
| number of pixels in x and y, symmetric for single value
| |
| allowed: | any |
|
| Default: | variant -1 |
|
cell |
| x and y cell size. default unit arcsec
| |
| allowed: | any |
|
| Default: | variant
|
|
center |
| Image center
| |
| allowed: | any |
|
| Default: | variant
|
|
plot |
| Plot result or not
| |
| allowed: | bool |
|
| Default: | False |
|
void
Example
Keyword arguments:
infiles -- a list of names of input SD datasets. in case input is a
single dataset, its name can be given as a string.
example: ’testimage.asap’
[’testimage1.asap’,’testimage2.asap’]
antenna -- select an antenna name or ID
default: -1
example: ’PM03’
NOTE this parameter is effective only for MS input
spw -- select data by IF IDs (spectral windows)
NOTE this task only supports IF ID selction and ignores channel
selection.
default: ’-1’ (only process IFNO in the first row)
example: spw=’3,5,7’ (IF IDs 3,5,7; all channels)
spw=’<2’ (IF IDs less than 2, i.e., 0,1; all channels)
spw=’30~45GHz’ (IF IDs with the center frequencies in range 30-45GHz; all channels)
this selection is in addition to the other selections to data
scan -- select data by scan numbers
default: ’’ (use all scans)
example: scan=’21~23’ (scan IDs 21,22,23)
this selection is in addition to the other selections to data
pol -- select data by polarization IDs
default: ’’ (use all polarizations)
example: pol=’0,1’ (polarization IDs 0,1)
this selection is in addition to the other selections to data
gridfunction -- gridding function
options: ’BOX’ (Box-car), ’SF’ (Spheroidal),
’GAUSS’ (Gaussian), ’PB’ (Primary-beam)
’GJINC’ (Gaussian*Jinc)
default: ’BOX’
example: ’SF’
>>> gridfunction expandable parameter:
convsupport -- convolution support for ’SF’
default: -1 (use default for each gridfunction)
example: 3
truncate -- truncattion radius of convolution kernel.
effective only for ’GAUSS’ and ’GJINC’.
default: ’-1’ (use default for each gridfunction)
example: 3, ’20arcsec’, ’3pixel’
gwidth -- HWHM for gaussian. Effective only for
’GAUSS’ and ’GJINC’.
default: ’-1’ (use default for each gridfunction)
example: 3, ’20arcsec’, ’3pixel’
jwidth -- Width of jinc function. Effective only for
’GJINC’.
default: ’-1’ (use default for each gridfunction)
example: 3, ’20arcsec’, ’3pixel’
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 -- name of output file
default: ’’ (outfile will be set to infile[0]+’.grid’)
example: ’mydata.asap.grid’
overwrite -- overwrite the output file if already exists
options: (bool) True,False
default: False
NOTE this parameter is ignored when outform=’ASCII’
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 sdgridold 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), ’GJINC’ (Gaussian*
Jinc), where Jinc(x) = J_1(pi*x/c)/(pi*x/c) with a first order
Bessel function J_1, and ’PB’ (Primary Beam, not implemented yet).
For ’PB’, correct antenna informations should be included in input
file.
There are four subparameters for gridfunction: convsupport, truncate,
gwidth, and jwidth. The convsupport is an integer specifying cut-off
radius for ’SF’ in units of pixel. By default (convsupport=-1),
the cut-off radius is set to 3 pixels. The truncate is a cut-off
radius for ’GAUSS’ or ’GJINC’. It accepts integer, float, and
string values of numeric plus unit. Allowed units are angular
units such as ’deg’, ’arcmin’, ’arcsec’, and ’pixel’. Default unit
is ’pixel’ so that string without unit or numerical values (integer
or float) will be interpreted as radius in pixel. Default value
for truncate, which is used when negative radius is set, is 3*HWHM
for ’GAUSS’ and radius at first null for ’GJINC’. The gwidth is
the HWHM of gaussian for ’GAUSS’ and ’GJINC’. Default value is
sqrt(log(2)) pixel for ’GAUSS’ and 2.52*sqrt(log(2)) pixel for
’GJINC’. The jwidth specifies width of the jinc function (parameter
’c’ in the definition above). Default is 1.55 pixel. Both gwidth
jwidth allows integer, float, or string of numeric plus unit.
Default values for gwidth and jwidth are taken from Mangum et al.
(2007). Formula for ’GAUSS’ and ’GJINC’ are taken from Table 1 in
the paper, and are written as below using gwidth and jwidth:
GAUSS: exp[-(|r|/gwidth)**2]
GJINC: J_1(pi*|r|/jwidth)/(pi*|r|/jwidth) * exp[-(|r|/gwidth)^2]
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.
Reference: Mangum, et al. 2007, A&A, 474, 679-687
More information about CASA may be found at the
CASA web page
Copyright © 2016 Associated Universities Inc., Washington, D.C.
This code is available under the terms of the GNU General Public Lincense
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