The first γ -ray detection of the narrow-line Seyfert 1 FBQS J1644+2619.

We report the discovery of γ -ray emission from the narrow-line Seyfert 1 (NLSy1) galaxy FBQS J1644+2619 by the Large Area Telescope on board the Fermi satellite. The Third Fermi LAT Source catalogue reports an unidentified γ -ray source, detected over the first four years of Fermi operation, 0.◦23 from the radio position of the NLSy1. Analysing 76 months of γ -ray data (2008 August 4-2014 December 31) we are able to better constrain the localization of the γ -ray source. The new position of the γ -ray source is 0.◦05 from FBQS J1644+2619, suggesting a spatial association with the NLSy1. This is the sixth NLSy1 detected at high significance by Fermi-LAT so far. Notably, a significant increase of activity was observed in γ -rays from FBQS J1644+2619 during 2012 July-October, and an increase of activity in the V band was detected by the Catalina Real-Time Sky Survey in the same period. [ABSTRACT FROM AUTHOR]