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.. _FITS:

FITS Flexible Image Transport System (FITS) format
==================================================

Extensions: ``.fits``, ``.fit``, ``.fts``

Flexible Image Transport System (FITS) is an open standard defining a
digital file format useful for storage, transmission and processing of
scientific and other images. FITS is the most commonly used digital
file format in astronomy.

This format requires the ``astropy`` package.

Parameters for reading
----------------------
cache : bool
    If the file name is a URL, `~astropy.utils.data.download_file` is used
    to open the file.  This specifies whether or not to save the file
    locally in Astropy's download cache (default: `True`).
uint : bool
    Interpret signed integer data where ``BZERO`` is the
    central value and ``BSCALE == 1`` as unsigned integer
    data.  For example, ``int16`` data with ``BZERO = 32768``
    and ``BSCALE = 1`` would be treated as ``uint16`` data.

    Note, for backward compatibility, the kwarg **uint16** may
    be used instead.  The kwarg was renamed when support was
    added for integers of any size.
ignore_missing_end : bool
    Do not issue an exception when opening a file that is
    missing an ``END`` card in the last header.
checksum : bool or str
    If `True`, verifies that both ``DATASUM`` and
    ``CHECKSUM`` card values (when present in the HDU header)
    match the header and data of all HDU's in the file.  Updates to a
    file that already has a checksum will preserve and update the
    existing checksums unless this argument is given a value of
    'remove', in which case the CHECKSUM and DATASUM values are not
    checked, and are removed when saving changes to the file.
disable_image_compression : bool, optional
    If `True`, treats compressed image HDU's like normal
    binary table HDU's.
do_not_scale_image_data : bool
    If `True`, image data is not scaled using BSCALE/BZERO values
    when read.
ignore_blank : bool
    If `True`, the BLANK keyword is ignored if present.
scale_back : bool
    If `True`, when saving changes to a file that contained scaled
    image data, restore the data to the original type and reapply the
    original BSCALE/BZERO values.  This could lead to loss of accuracy
    if scaling back to integer values after performing floating point
    operations on the data.


