A FITS File Subroutine Library
CFITSIO is a library of C and Fortran subroutines for reading and
writing data files in FITS (Flexible Image Transport System) data
format. CFITSIO provides simple high-level routines for reading and
writing FITS files that insulate the programmer from the internal
complexities of the FITS format. CFITSIO also provides many advanced
features for manipulating and filtering the informationin FITS files.