code: def download(odir: Path, source_url: str, irng: Sequence[int]):
      
      assert len(irng) == 2, 'specify start, stop indices'
  
      odir = Path(odir).expanduser()
      odir.mkdir(parents=True, exist_ok=True)
  
      ri = int(source_url.split('/')[-2][:2])
  
      for i in range(*irng):
          fn = f'index-{ri:2d}{i:02d}.fits'
          url = f'{source_url}{fn}'
          ofn = odir / fn
          if ofn.is_file():  # no clobber
              print('skipping', ofn)
              continue
          print(f'{url} => {ofn}', end='\r')
  
          urlretrieve(url, ofn)
docs: Download star index files.
      The default range was useful for my cameras.