FITS (Flexible Image Transport System) is the standard format for astronomical data from telescopes and instruments such as HST, Chandra, and JWST.

Transparent Access: Read FITS files with nc_open() after calling NC_FITS_initialize().

HDU-to-Group Mapping:

Primary HDU → root group; variable named image
Each extension HDU → child group named from EXTNAME or hdu_N
Binary/ASCII table HDUs → one netCDF variable per column

Metadata Mapping: BUNIT→units, BZERO→add_offset, BSCALE→scale_factor, BLANK→_FillValue; all other header keywords become string attributes.

Use Cases: HST imaging, Chandra X-ray data, JWST observations, any FITS-format observatory data.

Enabling:

cmake -B build -DNEP_ENABLE_FITS=ON # CMake

./configure --enable-fits # Autotools

Dependencies: CFITSIO ≥ 3.0.

Resources: FITS Standard · CFITSIO Home · FITS Documentation Index

Example:

#include "fitsdispatch.h"
NC_FITS_initialize();   /* register UDF3; safe to call even if already registered */
nc_open("image.fits", NC_NOWRITE, &ncid);
nc_inq_varid(ncid, "image", &varid);
nc_get_vara_float(ncid, varid, start, count, pixels);
nc_close(ncid);