#
# stub function definition file for docstring parsing
#
[docs]def exportfits(imagename, fitsimage='', velocity=False, optical=False, bitpix=-32, minpix=0, maxpix=-1, overwrite=False, dropstokes=False, stokeslast=True, history=True, dropdeg=False):
r"""
Convert a CASA image to a FITS file
[`Description`_] [`Examples`_] [`Development`_] [`Details`_]
Parameters
- imagename_ (path) - Name of input CASA image
- fitsimage_ (string='') - Name of output image FITS file
- velocity_ (bool=False) - Use velocity (rather than frequency) as spectral axis
- optical_ (bool=False) - Use the optical (rather than radio) velocity convention
- bitpix_ (int=-32) - Bits per pixel
- minpix_ ({int, double}=0) - Minimum pixel value (if minpix > maxpix, value is automatically determined)
- maxpix_ ({int, double}=-1) - Maximum pixel value (if minpix > maxpix, value is automatically determined)
- overwrite_ (bool=False) - Overwrite output file if it exists?
- dropstokes_ (bool=False) - Drop the Stokes axis?
- stokeslast_ (bool=True) - Put Stokes axis last in header?
- history_ (bool=True) - Write history to the FITS image?
- dropdeg_ (bool=False) - Drop all degenerate axes (e.g. Stokes and/or Frequency)?
.. _Description:
Description
The exportfits task exports CASA-produced images as FITS files for
transporting to other software packages or publication.
With the default settings, this task will produce FITS image files
with 4 dimensions: RA, Dec, radio frequency, and polarization
(Stokes parameters). Several options influence the shape of the
output data array. Setting dropstokes=True will cause the
polarization axis to be omitted. Setting velocity=True will cause
the spectral axis to have units of velocity rather than
frequency. Setting stokeslast=False will interchange the order of
the polarization and spectral axes (i.e, polarization will be the
third dimension, and frequency the fourth). Finally, setting
dropdeg=True will cause any "degenerate" axes, those with length
1, to be omitted. For example a total-intensity continuum image
would result in a 2-dimensional output array (RA, Dec only) when
using this option.
The bitpix parameter specifies the number of bits used to
represent a data value in the FITS image array. The allowed values
for bitpix are 16 or -32 meaning the data values are represented
as 16-bit twos-complement binary integer or IEEE single precision
floating point, respectively. We recommend using the default value
-32 in most cases. Using 16 bits results in smaller FITS files, at
the expense of dynamic range in the image. It may also be
necessary to use specific bitpix values depending on the
requirements of any external programs that will be reading the
FITS files.
The minpix and maxpix parameters are used to specifiy the minimum
and maximum data values when re-scaling to integers in the 16-bit
case; this affects the dynamic range of the exported image. Data
values outside this range will be clipped. If unspecified, these
will be determined automatically from the minimum and maximum data
values present.
Generally, the conversion follows the `official FITS standard
3.0. <https://fits.gsfc.nasa.gov/standard30/fits_standard30aa.pdf>`__
.. note:: Info: Note that no subimaging of the fits image can be made
with this task. The spectral reference frame can be changed
prior to export using the task imreframe.
.. _Examples:
Examples
Write a FITS image file that uses velocity rather than frequency
as the spectral axis, overwriting an existing file of the same
name if it already exists.
::
exportfits(imagename="my.im", fitsimage="my.fits", velocity =
True, overwrite=True)
Write a FITS image file that uses velocity rather than frequency
as the spectral axis and where the degenerate Stokes axis is
dropped (i.e. the product has only one value in the polarisation
dimension).
::
exportfits(imagename="my.im", fitsimage="my.fits", dropstokes =
True, velocity = True)
Note: if the imput image has a synthesized beam specfied, then the
major and minor axis (BMAJ and BMIN) may be specified in units of
degrees in the output fits-file.
.. _Development:
Development
No additional development details
.. _Details:
Parameter Details
Detailed descriptions of each function parameter
.. _imagename:
| ``imagename (path)`` - Name of input CASA image
| Default: none
| Example: fitsimage='3C273XC1.image'
.. _fitsimage:
| ``fitsimage (string='')`` - Name of output image FITS file
| Default: none
| Example: fitsimage='3C273XC1.fits'
.. _velocity:
| ``velocity (bool=False)`` - Use velocity (rather than frequency) as spectral axis
| Default: False
| Options: False|True
.. _optical:
| ``optical (bool=False)`` - Use the optical (rather than radio) velocity convention
| Default: False
| Options: False|True
.. _bitpix:
| ``bitpix (int=-32)`` - Bits per pixel
| Default: -32
| Example: bitpix=16
.. _minpix:
| ``minpix ({int, double}=0)`` - Minimum pixel value (if minpix > maxpix, value is automatically determined)
.. _maxpix:
| ``maxpix ({int, double}=-1)`` - Maximum pixel value (if minpix > maxpix, value is
| automatically determined)
| Default: -1
.. _overwrite:
| ``overwrite (bool=False)`` - Overwrite output file if it exists?
| Default: False
| Options: False|True
.. _dropstokes:
| ``dropstokes (bool=False)`` - Drop the Stokes axis?
.. _stokeslast:
| ``stokeslast (bool=True)`` - Put Stokes axis last in header?
| Default: True
| Options: True|False
.. _history:
| ``history (bool=True)`` - Write history to the FITS image?
| Default: True
| Options: True|False
.. _dropdeg:
| ``dropdeg (bool=False)`` - Drop all degenerate axes (e.g. Stokes and/or Frequency)?
| Default: False
| Options: False|True
"""
pass