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  : Integral fluxes above 200 GeV in the individual observation periods and reduced $\chi^2$/dof of a fit with a constant-flux ansatz in the respective observation periods. The given errors are statistical errors only.[]{data-label="tab:lc"}

Summing up all the data we determined an integral flux above 200 GeV of $$F(E>200 \mathrm{GeV}) =  (2.38 \pm {0.30_{\mathrm{stat}}} \pm
0.70_{\mathrm{syst}}) \times 10^{-11} \mathrm{cm}^{-2}
\mathrm{s}^{-1}.$$ The relatively large systematic error is a consequence of the steep spectral slope (see below). The main contributions to the systematic error are the uncertainties in the atmospheric transmission, the reflectivity (including stray-light losses) of the main mirror and the light catchers, the photon to photoelectron conversion calibration, and the photoelectron collection efficiency in the photomultiplier front end. Also, MC uncertainties and systematic errors from the analysis methods contribute significantly to the error. The above quoted flux corresponds to $(10\pm1)\%$ of the integral Crab Nebula flux in the same energy range. During our observations we also checked the optical variability. When correcting for the contribution of the host galaxy of 3.7 mJy [@KariO], variations in the optical light curve around the average brightness of $\approx 15\%$ are seen, which are significant given the small errors ($\lesssim 5\%$) of the 