  The Large Area Telescope on board the Fermi Gamma-ray Space Telescope
detected a strong gamma-ray flare on 2011 May 15 from a source identified as 4C
49.22, a flat spectrum radio quasar also known as S4 1150+49. This blazar,
characterised by a prominent radio-optical-X-ray jet, was in a low gamma-ray
activity state during the first years of Fermi observations. Simultaneous
observations during the quiescent, outburst and post-flare gamma-ray states
were obtained by Swift, Planck and optical-IR-radio telescopes (INAOE, Catalina
CSS, VLBA, Metsahovi). The flare is observed from microwave to X-ray bands with
correlated variability and the Fermi, Swift and Planck data for this FSRQ show
some features more typical of BL Lac objects, like the synchrotron peak in the
optical band that outshines the thermal blue-bump emission, and the X-ray
spectral softening. Multi-epoch VLBA observations show the ejection of a new
component close in time with the GeV gamma-ray flare. The radio-to-gamma-ray
spectral energy distribution is modeled and fitted successfully for the
outburst and the post-flare epochs using either a single flaring blob with two
emission processes (synchrotron self Compton, and external-radiation Compton),
and a two-zone model with SSC-only mechanism.
