Hi all, On the subject of FITS image viewers, it is important to remember that the FITS (Flexible Image Transport System, an acronym as all things in astrophysics) format is designed primarily for carrying astrophysical data. As a result, I would always recommend using a proper viewer like `fv` (https://heasarc.gsfc.nasa.gov/docs/software/ftools/fv/fv_download.html) or SAOImageDS9 (https://sites.google.com/cfa.harvard.edu/saoimageds9/download). One should be aware that the AUR package for the latter has been plagued with packaging issues, while the source code for the former is not distributed separately but only as a part of the full HEASoft package (though is under a FOSS license as the work of US government employees, and this is simply an issue of the way it's packaged and not a licensing thing). The main problem with a quote-unquote 'naïve' FITS image viewer is that there are many kinds of FITS files that are not actually images. While in this case it seems this file was actually an image, depending on the extensions in the file, it may be an event file, a spectrum file, or a table. So again I advise readers to consider using a proper tool to check FITS extensions and headers, since not all FITS files are images (despite the acronym). I have not used e.g. GIMP's tools to look at FITS images, but if it doesn't properly handle displaying the headers, or tabbing through multiple image extensions, then it's likely users will find that an inadequate solution. In a perfect world I think DS9 would get enough AUR votes to be considered for Extra status but I think that's unlikely.
Regards, Jack R. Uteg
