docs: def A_brighter(self, band='g'):
          """
          Instances where star A is brighter than (B+C)
          """
          mA = self.stars['{}_mag_A'.format(band)]
          mBC = addmags(self.stars['{}_mag_B'.format(band)],
                       self.stars['{}_mag_C'.format(band)])
          return mA < mBC