def _compute_magnitude_scaling_term(self, C, mag):
        """
        Compute and return magnitude scaling term in equation 2,
        page 970.
        """
        c1 = self.CONSTS['c1']
        if mag <= c1:
            return C['b1'] + C['b2'] * (mag - c1) + C['b3'] * (8.5 - mag) ** 2
        else:
            return C['b1'] + C['b7'] * (mag - c1) + C['b3'] * (8.5 - mag) ** 2
Compute and return magnitude scaling term in equation 2,
        page 970.