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Fig. 2


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Evolution of the monthly number of PF observations and monthly smoothed seeing Q, after having removed the days with poor seeing conditions (Q < 3). The period with higher Q-values (1996–2000) corresponds with the period observed from San Antonio, Texas, USA. A small jump in Q can be seen from 2003 onwards, when it was decided to favour observations with better seeing conditions over larger number of observations.

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