FTOOLS is a collection of utility programs used to create, examine, or modify the contents of FITS data files. There are also user friendly GUI tools which allow interactive browsing of FITS files and provide a more intuitive interface for running the FTOOLS. The FTOOLS package forms the core of the HEASARC software system for reducing and analyzing data in the FITS format.

Each FTOOLS task is a separate program that performs a single simple operation. The FTOOLS are primarily a Unix based package, although a Windows version was created for version 4.2 (a 5.0 version is in the works). Most of the powerful GUI interfaces run only on Unix, although the core GUI tool, fv, is available for Unix, Windows, and MacOS. Further discussion of supported platforms is available in the FTOOLS FAQ. Scripts are available for combining several FTOOLS to perform complex tasks. All of the core FTOOLS programs share several common design features:

  • All are written in ANSI Fortran or C;
  • All use a simple standardized subroutine interface for getting the value of program parameters (e.g., the name of the input FITS file), and;
  • All data I/O is restricted to FITS files via the FITSIO subroutine interface (or to simple ASCII format in certain cases).
  • All scripts are written in Perl5 (although many will work in Perl4). Note: The official Perl5.001 release doesn't work with all ftools scripts (due to a bug in the Perl code). To run ftools perl scripts, you will need "unofficial patchlevel" 5.001m or higher.
  • The GUI tools are written in Tcl/Tk: Currently there are fv (an interactive FITS file browser/editor) and xdf (the XTE Data Finder). The FTOOLS distribution contains the source for the Tcl/Tk interpreters that these tools need to run and will build them for you. You do not need to install Tcl or Tk separately on your system.

These design decisions have resulted in a software package that is exceptionally portable and can be integrated into new environments with a minimum of modification to the source code.

Useful Links


If FTOOLS has been useful in your research, please reference this site ( and use the ASCL reference for HEASoft [ascl:1408.004] or the ASCL reference for the original FTOOLs paper [ascl:9912.002]:

Blackburn, J. K. 1995, in ASP Conf. Ser., Vol. 77, Astronomical Data Analysis Software and Systems IV, ed. R. A. Shaw, H. E. Payne, and J. J. E. Hayes (San Francisco: ASP), 367.

Web page maintained by: Bryan K. Irby