FITSview looks like it is free and portable although it would probably have rather a small user base being intended primarily for scientists.

It may be obtained from http://www.nrao.edu/software/fitsview/ and I downloaded the fitsview.exe executable and fitsview.hlp files and installed them manually.

It seems to run fine and doesn't write much to the registry - it seems to record the folder of the last file opened for future browsing. I don't know if this rules it out as "portable" or just means that it is not "stealthy"?.

Thanks to @jwinter for a most interesting submission.
Something very different from normal and it got me intrigued.

Although I was trained as a "scientist" in my younger days, astronomy has its own jargon which takes some understanding.

Accordingly, I struggled to find FITS data on the Web in an understandable manner but eventually succeeded. If you can point me in the direction of some particularly interesting FITS data (for example the star Mira comes to mind) I would be grateful.

In the course of my efforts I came across another program which seemed to offer even more functionality ...

SAOImage DS9 V 5.7 at


It requires no installation and given that versions are around for Linux and Mac is likely to be portable.
Be interested in your opinion.

Once again, thanks for your valuable submission.

Thanks to JohnW for pointing me to DS9 - it does indeed seem to have a lot more bells and whistles than FITSview, and also seems to be actively maintained (three releases per year!). It also seems to be more portable than FITSview - in that it doesn't record the folder of the last file opened - you have to browse from scratch each time . I have now made DS9 the default FITS file viewer in my arsenal of portable freeware.

The place that I came across a lot of FITS image files was NED (Nasa Extragalactic Database) in which almost anything you chase up has a list of FITS files associated with it. Unfortunately you won't find Mira there as it is not extragalactic, but you might search for pretty galaxies - such as "sombrero" for instance. There are lots of FITS image files listed for sombrero, but for something of such common interest there are also some JPEGs. FITS files of course have the data arranged in a particular way, and no lossyness - and may not be image files anyway. In fact they don't seem to be capable of displaying colour - if you want colour then you end up with a "cube" of three separate gray level images giving each colour separately.