def get(self, telescope, band):
        """Get a Bandpass object for a known telescope and filter."""

        klass = self._bpass_classes.get(telescope)
        if klass is None:
            raise NotDefinedError('bandpass data for %s not defined', telescope)

        bp = klass()
        bp.registry = self
        bp.telescope = telescope
        bp.band = band
        return bp
Get a Bandpass object for a known telescope and filter.