MissFITS is a program that performs basic maintenance and packaging tasks on FITS files.
MissFITS uses its own optimized library to perform basic maintenance and packaging tasks on FITS files. The operations include adding/editing header keywords, splitting/joining multi-extension-FITS (MEF) files, packing/unpacking data cubes, and calculating/manipulating FITS checksums. Its syntax is similar to that of other astromatic.net tools like sextractor and swarp.
To install missfits, paste this in macOS terminal after installing MacPorts
sudo port install missfits