The Exceptional Flare of Mrk 501 in 2014: Combined Observations with H.E.S.S. and FACT

Understand

The BL Lac type object Mrk 501 was observed at very high energies (E > 100 GeV) in 2014 with the upgraded H.E.S.S.

• (High Energy Stereoscopic System) phase 2 array.
• The data collected with the central 28m telescope allow for a broader energy range extending to lower energies when compared to the one obtained with the four small telescopes alone.
• A strong flaring event with a flux level comparable to the 1997 historical maximum has been detected as a consequence of target of opportunity observations triggered by alerts from the FACT collaboration.