The FITS format is a general-purpose data storage format used primarily for the interchange of data between hardware platforms and software applications. FITS is the standard image data storage format for many astronomical organizations, including the astrophysics branch of NASA.
The default extension for FITS files is FIT
Supporting Platforms and Applications
This format is supported by numerous applications on a wide range of platforms.
PMView reads FITS files that contain an image with a BITPIX value of 8, 16, 32, -32, or -64. The value of NAXIS must be two (2) or greater.