We report the detection of very high-energy \gamma -ray emission from the intermediate-frequency-peaked BL Lacertae object W Comae ( z = 0.102 ) by VERITAS , an array of four imaging atmospheric-Cherenkov telescopes .
The source was observed between January and April 2008 .
A strong outburst of \gamma -ray emission was measured in the middle of March , lasting for only four days .
The energy spectrum measured during the two highest flare nights is fit by a power-law and is found to be very steep , with a differential photon spectral index of \Gamma = 3.81 \pm 0.35 _ { stat } \pm 0.34 _ { syst } .
The integral photon flux above 200 GeV during those two nights corresponds to roughly 9 \% of the flux from the Crab Nebula .
Quasi-simultaneous Swift observations at X-ray energies were triggered by the VERITAS observations .
The spectral energy distribution of the flare data can be described by synchrotron-self-Compton ( SSC ) or external-Compton ( EC ) leptonic jet models , with the latter offering a more natural set of parameters to fit the data .