Simultaneous X-ray and TeV observations of a rapid flare from markarian 421

Maraschi, L; Fossati, G; Tavecchio, E; Chiappetti, L; Celotti, A; Ghisellini, G; Grandi, P; Pian, E; Tagliaferri, G; Treves, Aldo; Breslin, Ac; Buckley, Jh; CARTER LEWIS, Da; Catanese, M; Cawley, Mf; Fegan, Dj; Fegan, S; Finley, J; Gaidos, J; Hall, T; Hillas, Am; Krennrich, F; Lessard, Rw; Masterson, C; Moriarty, P; Quinn, J; Rose, J; Samuelson, F; Weekes, Tc; Urry, Cm; Takahashi, T.