* Astronomy

Title: Discovery of transient high-energy gamma-ray emission from the BL Lacertae object 5C 3.178
Authors: Hugh Dickinson, Christian Farnier

We report the discovery of transient, point-like high energy gamma-ray emission coincident with the position of the suspected BL Lac object 5C 3.178. The source was detected using the Fermi Large Area Telescope (LAT) at a significance level of ~8 sigma during a 200 day period which began on MJD 55882. The observed gamma-ray emission is characterised by a moderate 0.2-300 GeV flux F(0.2-300 GeV)=(8.22±2.04) x 10^{-9} ph cm^{-2}s^{-1} and a hard power law spectrum with spectral index \Gamma=1.76±0.09. These properties appear consistent with the known sub-population of TeV gamma-ray-emitting BL Lac objects, implying that the source may be detectable using atmospheric Cherenkov telescope arrays.

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