SunPy IO

This submodule contains two types of routines, the first reads (data, header) pairs from files in a way similar to FITS files. The other is special readers for files that are commonly used in solar physics.


When reading FITS files, it is strongly recommended that be used over the tools in The sunpy FITS reader is designed to meet the needs of map, and does not represent the structure of the FITS file well.

Special File Readers Module

This module implements a solarsoft genx file reader.



solarsoft genx file reader.

asdf (Advanced Scientific Data Format)

asdf is a modern file format designed to meet the needs of the astronomy community. It has deep integration with Python and SunPy and Astropy as well as implementations in other languages. It can be used to store known Python objects in a portable, well defined file format. It is primarily useful for storing complex Astropy and SunPy objects in a way that can be loaded back into the same form as they were saved.

SunPy currently implements support for saving Map and coordinate frame objects into asdf files. As asdf tightly integrates into Python, saving a map to an asdf file will save the metadata, data, mask and the shift. The mask and shift are not currently saved to FITS. The following code shows to to save and load a SunPy Map to an asdf file

>>> import asdf
>>> import
>>> from import AIA_171_IMAGE  
>>> aiamap =  
>>> tree = {'amap': aiamap}  
>>> with asdf.AsdfFile(tree) as asdf_file:  
...     asdf_file.write_to("sunpy_map.asdf")  
>>> input_asdf ="sunpy_map.asdf")  
>>> input_asdf['amap']  
  < object at ...>
  SunPy Map
  Observatory:                 SDO
  Instrument:          AIA 3
  Detector:            AIA
  Measurement:                 171.0 Angstrom
  Wavelength:          171.0 Angstrom
  Observation Date:    2011-06-07 06:33:02
  Exposure Time:               0.234256 s
  Dimension:           [1024. 1024.] pix
  Coordinate System:   helioprojective
  Scale:                       [2.402792 2.402792] arcsec / pix
  Reference Pixel:     [511.5 511.5] pix
  Reference Coord:     [3.22309951 1.38578135] arcsec
  array([[ -95.92475  ,    7.076416 ,   -1.9656711, ..., -127.96519  ,
          -127.96519  , -127.96519  ],
         [ -96.97533  ,   -5.1167884,    0.       , ...,  -98.924576 ,
          -104.04137  , -127.919716 ],
         [ -93.99607  ,    1.0189276,   -4.0757103, ...,   -5.094638 ,
           -37.95505  , -127.87541  ],
         [-128.01454  , -128.01454  , -128.01454  , ..., -128.01454  ,
          -128.01454  , -128.01454  ],
         [-127.899666 , -127.899666 , -127.899666 , ..., -127.899666 ,
          -127.899666 , -127.899666 ],
         [-128.03072  , -128.03072  , -128.03072  , ..., -128.03072  ,
          -128.03072  , -128.03072  ]], dtype=float32)
 >>> input_asdf.close()  

Unified File Readers Package



Atempts to determine the type of file a given filepath is.

read_file(filepath[, filetype])

Automatically determine the filetype and read the file.

read_file_header(filepath[, filetype])

Reads the header from a given file.

write_file(fname, data, header[, filetype])

Write a file from a data & header pair using one of the defined file types. Module

This module provides a generic FileHeader object for the readers.


FileHeader(*args, **kwargs)

FileHeader is designed to provide a consistent interface to all other sunpy classes that expect a generic file.

Class Inheritance Diagram

Inheritance diagram of Module

This module provides a FITS file reader.


  1. FITS files allow comments to be attached to every value in the header. This is implemented in this module as a KEYCOMMENTS dictionary in the sunpy header. To add a comment to the file on write, add a comment to this dictionary with the same name as a key in the header (upcased).

  2. Due to the way fits works with images, the header dictionary may differ depending on whether is accessed before or after the fits[0].data is requested. If the header is read before the data then the original header will be returned. If the header is read after the data has been accessed then the data will have been scaled and a modified header reflecting these changes will be returned: BITPIX may differ and BSCALE and B_ZERO may be dropped in the modified version.

  3. The verify(‘silentfix+warn’) call attempts to handle violations of the FITS standard. For example, nan values will be converted to “nan” strings. Attempting to cast a to a dictionary while it contains invalid header tags will result in an error so verifying it early on makes the header easier to work with later.



Convert a header dict to a Header.

read(filepath[, hdus, memmap])

Read a fits file.


Read a fits file and return just the headers for all HDU's.

write(fname, data, header[, hdu_type])

Take a data header pair and write a FITS file.


Attempt to read the wavelength unit from a given FITS header. Module

This module provides a JPEG 2000 file reader.


read(filepath, **kwargs)

Reads a JPEG2000 file.


Reads the header from the file.

write(fname, data, header)

Place holder for required file writer. Module

This module provides an ANA file Reader.

This is a modified version of pyana.


The reading and writing of ana files is not supported under Windows.


read(filename[, debug])

Loads an ANA file and returns the data and a header in a list of (data, header) tuples.

get_header(filename[, debug])

Loads an ANA file and only return the header consisting of the dimensions, size (defined as the product of all dimensions times the size of the datatype, this not relying on actual filesize) and comments.

write(filename, data[, comments, compress, ...])

Saves a 2D numpy.array as an ANA file and returns the bytes written or NULL.