Top panel: average off-limb spectra of Ca ii H with increasing limb distance d. Middle panel: intensity variation with limb distance for the wavelengths marked in Fig. 6. The limb is denoted by a vertical black dashed line. The right scale uses the same units as in Zirker (1962). Bottom: the energy of the radiation integrated over the line-core region. The black vertical bars denote the energy as given by BE68, and after division by a factor of 5.5, respectively (red).