healpy.fitsfunc.write_map(filename, m, nest=False, dtype=<class 'numpy.float32'>, fits_IDL=True, coord=None, partial=False, column_names=None, column_units=None, extra_header=(), overwrite=False)

Writes a healpix map into a healpix file.


the fits file name

marray or sequence of 3 arrays

the map to write. Possibly a sequence of 3 maps of same size. They will be considered as I, Q, U maps. Supports masked maps, see the ma function.

nestbool, optional

If True, ordering scheme is assumed to be NESTED, otherwise, RING. Default: RING. The map ordering is not modified by this function, the input map array should already be in the desired ordering (run ud_grade beforehand).

fits_IDLbool, optional

If True, reshapes columns in rows of 1024, otherwise all the data will go in one column. Default: True


The coordinate system, typically ‘E’ for Ecliptic, ‘G’ for Galactic or ‘C’ for Celestial (equatorial)

partialbool, optional

If True, fits file is written as a partial-sky file with explicit indexing. Otherwise, implicit indexing is used. Default: False.

column_namesstr or list

Column name or list of column names, if None here the default column names based on the number of columns: 1 : “TEMPERATURE”, 2 : [“Q_POLARISATION”, “U_POLARISATION”], 3 : [“TEMPERATURE”, “Q_POLARISATION”, “U_POLARISATION”], 6 : [“II”, “IQ”, “IU”, “QQ”, “QU”, “UU”] COLUMN_1, COLUMN_2… otherwise (FITS is 1-based)

column_unitsstr or list

Units for each column, or same units for all columns.


Extra records to add to FITS header.

dtype: np.dtype or list of np.dtypes, optional

The datatype in which the columns will be stored. Will be converted internally from the numpy datatype to the fits convention. If a list, the length must correspond to the number of map arrays. Default: np.float32.

overwritebool, optional

If True, existing file is silently overwritten. Otherwise trying to write an existing file raises an OSError (IOError for Python 2).