We have considered the Fermi γ-ray light curve of the blazar PKS 0537–441 during a high state extending from 2008 August 10 to 2011 August 27. The periodogram exhibits a peak at T ~ 280 days, with a significance of ~99.7%. A peak of similar relevance at is found in the optical light curves. Considering the entire duration of the Fermi light curve 2008–2015, no significant peak is revealed, while the optical one remains meaningful. Comparing with recent observations of PKS 2155–304 and PG 1553+113 it seems that month–year oscillations can characterize some blazars. Month-scale oscillations can also show up only during phases of enhanced or bursting emission, such as in the case of PKS 0537–441.
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