FITS (Flexible Image Transport System) is a data format most used in astronomy. cfitsio is a library of ANSI C routines for reading and writing FITS format data files. A set of Fortran-callable wrapper routines are also included for the convenience of Fortran programmers. . This package contains the CFITSIO User's Guide and QuickStart Guide in html, postscript and text formats, and contains documentation on how to use the library in your programs.