code: def get_AV_infinity(ra,dec,frame='icrs'):
      
      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'
  
      AV = None
      for line in urllib.request.urlopen(url).readlines():
          m = re.search(b'^Landolt V \(0.54\)\s+(\d+\.\d+)', line)
          if m:
              AV = (float(m.group(1)))
              break
  
      if AV is None:
          raise RuntimeError('AV query fails!  URL is {}'.format(url))
  
      return AV
docs: Gets the A_V exctinction at infinity for a given line of sight.
  
      Queries the NED database.
  
      :param ra,dec:
          Desired coordinates, in degrees.
      :param frame: (optional)
          Frame of input coordinates (e.g., ``'icrs', 'galactic'``)