GammaLib (http://cta.irap.omp.eu/gammalib/)
A versatile toolbox for scientific analysis of astronomical gamma-ray data.
cfitsio (http://heasarc.gsfc.nasa.gov/fitsio/)
Library of C and Fortran subroutines for reading and writing data files in FITS data format.
FITS (http://fits.gsfc.nasa.gov/)
Flexible Image Transport System.
FTOOLS (http://heasarc.gsfc.nasa.gov/ftools/)
Collection of utility programs to create, examine, or modify data files in the FITS data format.
GNU (http://www.gnu.org/)
A free Unix-like operating system.
HEASARC (http://heasarc.gsfc.nasa.gov/)
High Energy Astrophysics Science Archive Research Centre.
Python (http://www.python.org/)
Dynamic programming language that is used in a wide variety of application domains.