code: def from_sky(cls, distancelimit=15, magnitudelimit=18):
          '''
          Create a Constellation from a criteria search of the whole sky.
  
          Parameters
          ----------
          distancelimit : float
              Maximum distance (parsecs).
          magnitudelimit : float
              Maximum magnitude (for Gaia G).
  
          '''
  
          # define a query for cone search surrounding this center
          criteria = []
          if distancelimit is not None:
              criteria.append('parallax >= {}'.format(1000.0/distancelimit))
          if magnitudelimit is not None:
              criteria.append('phot_g_mean_mag <= {}'.format(magnitudelimit))
  
          allskyquery = .format(cls.basequery, ' and '.join(criteria))
          print(allskyquery)
  
          # run the query
          print('querying Gaia DR2, for distance<{} and G<{}'.format(distancelimit, magnitudelimit))
          table = query(allskyquery)
  
          # store the search parameters in this object
          c = cls(cls.standardize_table(table))
  
          c.standardized.meta['query'] = allskyquery
          c.standardized.meta['magnitudelimit'] = magnitudelimit
          c.standardized.meta['distancelimit'] = distancelimit
  
          #c.distancelimit = distancelimit
          #c.magnitudelimit = magnitudelimit or c.magnitudelimit
          return c
docs: Create a Constellation from a criteria search of the whole sky.
  
          Parameters
          ----------
          distancelimit : float
              Maximum distance (parsecs).
          magnitudelimit : float
              Maximum magnitude (for Gaia G).