Create a Constellation from a criteria search of the whole sky.

        Parameters
        ----------
        magnitudelimit : float
            Maximum magnitude (for Ve = "estimated V").

def from_sky(cls, magnitudelimit=None):
        '''
        Create a Constellation from a criteria search of the whole sky.

        Parameters
        ----------
        magnitudelimit : float
            Maximum magnitude (for Ve = "estimated V").
        '''


        # define a query for cone search surrounding this center

        criteria = {}
        if magnitudelimit is not None:
            criteria[cls.defaultfilter + 'mag'] = '<{}'.format(magnitudelimit)

        v = Vizier(columns=cls.columns,
                   column_filters=criteria)
        v.ROW_LIMIT = -1

        # run the query
        print('querying Vizier for {}, for {}<{}'.format(cls.name, cls.defaultfilter, magnitudelimit))

        table = v.query_constraints(catalog=cls.catalog, **criteria)[0]

        # store the search parameters in this object
        c = cls(cls.standardize_table(table))
        c.standardized.meta['catalog'] = cls.catalog
        c.standardized.meta['criteria'] = criteria
        c.standardized.meta['magnitudelimit'] = magnitudelimit or c.magnitudelimit
        #c.magnitudelimit = magnitudelimit or c.magnitudelimit
        return c