Problem opening FITS files.

American Association of Variable Star Observers (AAVSO)
Sun, 04/04/2021 - 23:05


As a newbie into spectroscopy I have been viewing other on-line FITS files with either AIP4Win, SiriL, ASIStudio, or FITS Liberator with no problem.  Yet when I download any FITS from AVspec...I keep getting errors.

I save the zip file and uncompress it. When I bring it into the aforementioned programs .. they cannot not read it. Usually I get a "file format is not correct" message.

I have been able to open the FITS with Notepad and can see the data.
I think a common factor may be the following  - the common fields are:

SIMPLE  =                    T / file does conform to FITS standard
NAXIS   =                    1 / number of data axes

I am making an educated guess, the problem maybe its conformity and a one-dimension specta???

I know there there are many steps to take an image...but the inability to view AVSpec's FITS images is a bit frustrating.

I have looked through this forum and cannot find any reference to my issue.

Any suggestions?

Thank you,


British Astronomical Association, Variable Star Section (BAA-VSS)
1D fits files

Hi Paul,

Imaging programs like AIP4Win etc expect fits files to be images but fits files can contain any information. In this case they are spectrum profiles of intensity v wavelength. (A list of intensities and information in the header about the starting wavelength and the spacing). You need a program specifically designed to read this sort of data. For example I use ISIS for all my spectrum processing



British Astronomical Association, Variable Star Section (BAA-VSS)
Some programs

A few examples of popular programs for amateurs  which can display and manipulate fits spectral profiles


Visual Spec



BASS project