docs: def get_AV_infinity(ra,dec,frame='icrs'):
      """
      Gets the A_V exctinction at infinity for a given line of sight.
  
      Queries the NED database using ``curl``.
  
      .. note::
  
          It would be desirable to rewrite this to avoid dependence
          on ``curl``.
  
      :param ra,dec:
          Desired coordinates, in degrees.
  
      :param frame: (optional)
          Frame of input coordinates (e.g., ``'icrs', 'galactic'``)
      """
      coords = SkyCoord(ra,dec,unit='deg',frame=frame).transform_to('icrs')
  
      rah,ram,ras = coords.ra.hms
      decd,decm,decs = coords.dec.dms
      if decd > 0:
          decsign = '%2B'
      else:
          decsign = '%2D'
      url = 'http://ned.ipac.caltech.edu/cgi-bin/nph-calc?in_csys=Equatorial&in_equinox=J2000.0&obs_epoch=2010&lon='+'%i' % rah + \
          '%3A'+'%i' % ram + '%3A' + '%05.2f' % ras + '&lat=%s' % decsign + '%i' % abs(decd) + '%3A' + '%i' % abs(decm) + '%3A' + '%05.2f' % abs(decs) + \
          '&pa=0.0&out_csys=Equatorial&out_equinox=J2000.0'
  
      tmpfile = '/tmp/nedsearch%s%s.html' % (ra,dec)
      cmd = 'curl -s \'%s\' -o %s' % (url,tmpfile)
      sp.Popen(cmd,shell=True).wait()
      AV = None
      with open(tmpfile, 'r') as f:
          for line in f:
              m = re.search('V \(0.54\)\s+(\S+)',line)
              if m:
                  AV = float(m.group(1))
      if AV is None:
          logging.warning('Error accessing NED, url={}'.format(url))
          with open(tmpfile) as f:
              for line in f:
                  logging.warning(line)
  
  
  
      os.remove(tmpfile)
      return AV