docs: def fits_list(filter,root,fnames):
      """Get a list of files matching filter in directory root"""
      import re, pyfits, wcsutil
      for file in fnames:
          if re.match(filter,file):
              fh=pyfits.open(file)
              for ext in fh:
                  obj=ext.header.get('OBJECT',file)
                  dx=ext.header.get('NAXIS1',None)
                  dy=ext.header.get('NAXIS2',None)
                  wcs=wcsutil.WCSObject(ext)
                  (x1,y1)=wcs.xy2rd((1,1,))
                  (x2,y2)=wcs.xy2rd((dx,dy))
                  ccds=[x1,y1,x2,y2]
                  pointing={'label': obj, 'camera': ccds}
      return files