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We report on multiwavelength observations of the blazar PKS 0537-441 (z =0.896) obtained from microwaves through gamma rays by SMA, REM, ATOM, Swift andFermi during 2008 August-2010 April. Strong variability has been observed ingamma rays, with two major flaring episodes (2009 July and 2010 March) and aharder-when-brighter behaviour, quite common for FSRQs andlow-synchrotron-peaked BL Lacs, in 2010 March. In the same way the SED of thesource cannot be modelled by a simple synchrotron self-Compton model, asopposed to many BL Lacs, but the addition of an external Compton component ofseed photons from a dust torus is needed. The 230 GHz light curve showed anincrease simultaneous with the gamma-ray one, indicating co-spatiality of themm and gamma-ray emission region likely at large distance from the centralengine. The low, average, and high activity SED of the source could be fitchanging only the electron distribution parameters, but two breaks in theelectron distribution are necessary. The ensuing extra spectral break, locatedat NIR-optical frequencies, together with that in gamma rays seem to indicate acommon origin, most likely due to an intrinsic feature in the underlyingelectron distribution. An overall correlation between the gamma-ray band withthe R-band and K-band has been observed with no significant time lag. On theother hand, when inspecting the light curves on short time scales somedifferences are evident. In particular, flaring activity has been detected inNIR and optical bands with no evident gamma-ray counterparts in 2009 Septemberand November. Moderate variability has been observed in X-rays with nocorrelation between flux and photon index. An increase of the detected X-rayflux with no counter part at the other wavelengths has been observed in 2008October, suggesting once more a complex correlation between the emission atdifferent energy bands.

Long-term monitoring of PKS 0537-441 with Fermi-LAT and multiwavelength observations