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sip_tpv
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Utilities for converting between the SIP convention for representing distortion
in FITS images, and the TPV convention. Usage may look like::

    from astropy.io import fits
    from sip_tpv import pv_to_sip

    hdulist = fits.open('input.fits')
    for hdu in hdulist:
        pv_to_sip(hdu.header)

(hdulist is a collection of HDU objects)

License
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Licensed under a 3-clause BSD style license - see LICENSE.txt

This module includes the equations for converting from the SIP distortion representation
to the PV or TPV representations, following the SPIE proceedings paper at
http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=1363103
and http://web.ipac.caltech.edu/staff/shupe/reprints/SIP_to_PV_SPIE2012.pdf .

The work described in that paper is extended to 7th order.

Copyright (c) 2012-2014, California Institute of Technology

If you make use of this work, please cite::

    "More flexibility in representing geometric distortion in astronomical images,"
    Shupe, David L.; Laher, Russ R.; Storrie-Lombardi, Lisa; Surace, Jason; Grillmair, Carl;
    Levitan, David; Sesar, Branimir, 2012, in Software and Cyberinfrastructure for
    Astronomy II. Proceedings of the SPIE, Volume 8451, article id. 84511M.

Contributors
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* David Shupe, IPAC/Caltech (shupe@ipac.caltech.edu)
* Austin Beauchamp (austinbeauch@gmail.com)

Thanks also to
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* Thanks to Octavi Fors for contributing code modifications for better modularization, and for extensive testing.
* Funding is acknowledged from NASA to the NASA Herschel Science Center and the
  Spitzer Science Center.