User Interface: altwcs

The functions in this module manage alternate WCS’s in a header.

stwcs.wcsutil.altwcs.archiveWCS(fname, ext, wcskey=' ', wcsname=' ', reusekey=False)

Deprecated since version 1.6.0: The archiveWCS function is deprecated and may be removed in a future version. Use archive_wcs instead.

Copy the primary WCS to the header as an alternate WCS with wcskey and name WCSNAME. It loops over all extensions in ‘ext’

Parameters:

  • fname (string or astropy.io.fits.HDUList) – file name or a file object

  • ext (int, tuple, str, or list of integers or tuples (e.g.('sci',1))) – fits extensions to work with If a string is provided, it should specify the EXTNAME of extensions with WCSs to be archived

  • wcskey (string "A"-"Z" or " ") – if ' ': get next available key if wcsname is also ' ' or try to get a key from WCSNAME value

  • wcsname (string) – Name of alternate WCS description

  • reusekey (bool) – if True - overwrites a WCS with the same key

Examples

Copy the primary WCS of an in memory headrlet object to an alternate WCS with key ‘T’

>>> hlet=headerlet.createHeaderlet('junk.fits', 'hdr1.fits')
>>> altwcs.wcskeys(hlet[1].header)
['A']
>>> altwcs.archiveWCS(hlet, ext=[('SIPWCS',1),('SIPWCS',2)], wcskey='T')
>>> altwcs.wcskeys(hlet[1].header)
['A', 'T']

See also

wcsutil.restoreWCS

Copy an alternate WCS to the primary WCS

stwcs.wcsutil.altwcs.restoreWCS(f, ext, wcskey=' ', wcsname=' ')

Copy a WCS with key “WCSKEY” to the primary WCS

Reads in a WCS defined with wcskey and saves it as the primary WCS. Goes sequentially through the list of extensions in ext. Alternatively uses ‘fromext’ and ‘toext’.

Parameters:

  • f (str or astropy.io.fits.HDUList) – file name or a file object

  • ext (int, tuple, str, or list of integers or tuples (e.g.('sci',1))) – fits extensions to work with If a string is provided, it should specify the EXTNAME of extensions with WCSs to be archived

  • wcskey (str) – “A”-“Z” - Used for one of 26 alternate WCS definitions. or “ “ - find a key from WCSNAMe value

  • wcsname (str) – (optional) if given and wcskey is “ “, will try to restore by WCSNAME value

See also

archiveWCS, restore_from_to

stwcs.wcsutil.altwcs.deleteWCS(fname, ext, wcskey=' ', wcsname=' ')

Delete an alternate WCS defined with wcskey. If wcskey is “ “ try to get a key from WCSNAME.

Parameters:

  • fname (str or a astropy.io.fits.HDUList)

  • ext (int, tuple, str, or list of integers or tuples (e.g.('sci',1))) – fits extensions to work with If a string is provided, it should specify the EXTNAME of extensions with WCSs to be archived

  • wcskey (str) – one of ‘A’-‘Z’ or “ “

  • wcsname (str) – Name of alternate WCS description

stwcs.wcsutil.altwcs.wcsnames(fobj, ext=None, include_primary=True)

Returns a dictionary of wcskey: WCSNAME pairs

Parameters:
stwcs.wcsutil.altwcs.wcskeys(fobj, ext=None)

Returns a list of characters used in the header for alternate WCS description with WCSNAME keyword

Parameters:
stwcs.wcsutil.altwcs.available_wcskeys(fobj, ext=None)

Returns a list of characters which are not used in the header with WCSNAME keyword. Any of them can be used to save a new WCS.

Parameters:
stwcs.wcsutil.altwcs.next_wcskey(fobj, ext=None)

Returns next available character to be used for an alternate WCS

Parameters:
stwcs.wcsutil.altwcs.getKeyFromName(header, wcsname)

If WCSNAME is found in header, return its key, else return None. This is used to update an alternate WCS repeatedly and not generate new keys every time.

Parameters: