Hello Pedro,
Nice to meet you here
Yes, this is a bug. Excellent catch!
I have identified and fixed this problem. As you probably know, the PixInsight/PCL framework relies on the CFITSIO library from NASA/HEASARC for FITS support. The main CFITSIO routine for opening a FITS file, namely:
int fits_open_file( fitsfile** fptr, char* filename, int iomode, int* status )
uses an extended file naming convention to add some functionality to the basic file opening task. In particular, if a file name contains something between brackets, e.g. "[FOO]", CFITSIO will open the file and move directly to a FITS extension whose name is "FOO". Obviously, there is no "[3.0,2.4]" FITS extension in the FITS file that you've used, and hence CFITSIO has failed to open it.
Fortunately, CFITSIO has an alternative:
int fits_open_diskfile( fitsfile** fptr, char* filename, int iomode, int* status )
that does not make use of the extended naming syntax. So the cure to this problem is simply replacing all occurrences of fits_open_file() with fits_open_diskfile().
Thank you for your bug hunt. This one will be fixed (along with another that I'll report on a separate message) in build 202, which I'll upload in a couple of days.
Juan