FITS

FITS , or Flexible Image Transport System, is the standard image format used by astronomers

Reference

FITS , HEARSARC
FITS , Wikipedia

Description

A lot of professional astronomical software uses Tcl/Tk for its GUI, FITS as its graphics file format, and GPL as its license.

Tcl/Tk software for FITS files

SAOTk
an extension of Tk for visualization/analysis/imaging of FITS data
ds9
application built around SAOTk and several other components
fitsTcl
an extension of Tcl for accessing FITS data
fv
FITS file editor built using fitsTcl and several other components
TclMagick
a Tcl wrapper for ImageMagick or GraphicsMagick , can be used to convert to and from FITS format (appears to create monochrome FITS files only).

DS9 and fv are supplied as standalone binaries, but if the correct components are built and installed, each can be run as a Tcl script. Because this is not the intended mode of operation, the non-standard bundled components are not always supplied as packages and may need to be loaded with load.

Other Software for FITS files

Netpbm
can be used to convert to or from FITS
funtools
FITS Users Need Tools
HEASoft
A unified FTOOLS and XANADU distribution, includes many tools

FITS File Repositories

SkyView
many others...