FITS stands for Flexible Image Transport System. It is a digital file format used to store, transmit, and manipulate scientific and other images in astronomy. FV is a free software program to open, view and edit FITS images files. It supports number of editing features like: compute statistics about images or table columns, make ASCII listings of contents of any image or table.
You can also sort, merge, join, or filter rows of a table. You can pan and zoom displayed images in the viewer. Besides editing functionality it is a handy program to view astronomy images. It is available for free download and use for different platforms including Windows, Linux, Mac OSX. Download FV FITS viewer