We recommend that the team use the FITSVERIFY validator available from HEASARC and fix any problems with the files BEFORE delivery of the data, thus reducing the number of iterations required. You can also verify your FITS files online at http://fits.gsfc.nasa.gov/fits_verify.html.

Instructions for reading and writing FITS files can be found within the standard data reduction packages such as IRAF and STSDAS, and within the CFITSIO package distributed by HEASARC at http://heasarc.gsfc.nasa.gov/docs/software/fitsio/fitsio.html.