Interpreting the July 1997 observations of BL Lacertae

We use multiwavelength data collected during the high state of BL Lacertae in July 1997 to study the high energy radiation processes that are likely t o be responsible for the radiative output from relativistic jet in this obj ect. We show that the broad-band spectrum measured in July 1997 can be expl ained in terms of the model where the GeV gamma-rays are produced by Compto nization of broad emission line photons, while X-rays result from Comptoniz ation of synchrotron radiation internal to the jet. The model parameters ca lculated by us in this scenario are: magnetic field intensity B' similar to 1 Gauss; the bulk Lorentz factor of the jet Gamma(j) similar to 8; and the maximum electron energy gamma'(e,max) similar to 4 X 10(3). For these para meters the spectrum bleak due to synchrotron self-absorption is located at upsilon(a) similar or equal to 4 X 10(11) Hz, which is consistent with obse rvations.