Smoothed monthly values of observed PF (top) as recorded by the author (PF_JJ) and PF values (bottom) which are corrected for B₀ and seeing (PFc_JJ). The effect from the B₀ corrections can readily be seen as a significant reduction of the seasonal variation of the hemispheric PF numbers. The seeing correction concerns both the removal of days with poor seeing and a baselining of all observations to Q = 3.5. Both figures show the hemispheric values (North “n” in blue, South “s” in red) and the totals (green).