Tenmon FITS and XISF viewer

FITS and XISF image viewer, converter and indexer. It is intended primarily for viewing astro photos and images. It supports the following formats:

  • FITS 8, 16 bit integer and 32 bit float
  • XISF 8, 16 bit integer and 32 bit float
  • JPEG and PNG images
  • CR2 NEF DNG RAW images


  • Using same stretch function as PixInsight
  • OpenGL accelerated drawing
  • Index and search FITS XISF header data
  • Quick mark images and then copy/move marked files
  • Convert FITS <-> XISF
  • Convert FITS/XISF -> JPEG/PNG
  • Image statistics mean, media, min, max
  • Support for WCS
  • Thumbnails

You can download source code or pre-build binaries for Windows and MacOS here
On Linux you can install flatpak from flathub.org by running this command
flatpak install flathub space.nouspiro.tenmon