The smoothed initial monthly number of PF after removal of the observations with Q < 3 (orange curve), the overall reduced number of PF following the correction for B₀ (brown curve), and the final corrected PFc_JJ (green curve) after an additional correction for the varying seeing (see Fig. 3). The correction for B₀ results in an overall decrease of the PF numbers by 12–18%. The correction for seeing decreases the PF numbers prior to SC23, but mostly increases the PF numbers prior to SC24 and SC25.