Table 1: Fit results for different spectral models for the whole emission region within an integration radius of 0.8$^\circ $ around the best fit position and the background derived from off-data. The differential flux normalisation I0 is given in units of $10^{-12} ~ {\rm cm}^{-2} ~ {\rm s}^{-1} ~ {\rm TeV}^{-1}$. E, $E_{{\rm B}}$, and $E_{{\rm c}}$ are given in units of TeV. The last column gives the integrated flux above the spectral analysis threshold of 270 GeV in units of $10^{-11}~ {\rm cm}^{-2} ~ {\rm s}^{-1}$. The power-law fit provides a rather poor description of the data. Thus fits of a power law with an exponential cutoff (row 2), a power law with an energy dependent photon index (row 3), and a broken power law (row 4; in the formula, the parameter S = 0.1 describes the sharpness of the transition from $\Gamma _1$ to $\Gamma _2$ and is fixed in the fit) are also given. Note that some of the fit parameters are highly correlated.

Fit formula for $\frac{{\rm d} N}{{\rm d} E}$		 Fit parameters   $\chi ^2$ (ndf) Flux $_{> 270~{\rm GeV}}$

$\displaystyle{I_0\ E ^ {-\Gamma}}$		 $I_0 = 19.8 \pm 0.4$ $\Gamma = 2.38 \pm 0.02$     40.4 (15) $87.4 \pm 2.0$
$\displaystyle{I_0\ E ^ {-\Gamma}\ \exp (-E / E_{{\rm c}})}$ $I_0 = 21.0 \pm 0.5$ $\Gamma = 2.26 \pm 0.03$ $E_{{\rm c}} = 24.8 \pm 7.2 $   16.9 (14) $86.7 \pm 2.5$
$\displaystyle{I_0\ E ^ {-\Gamma + ~ \beta\ \log E}}$ $I_0 = 21.0 \pm 0.4$ $\Gamma = 2.29 \pm 0.02$ $\beta = -0.17 \pm 0.04 $   14.5 (14) $82.8 \pm 2.2$
$\displaystyle{I_0\ \left( E / E_{{\rm B}} \right) ^ {-\Gamma_1}\ \left( 1 + \left(E / E_{{\rm B}}\right) ^ {1 / S } \right) ^ {~ S ~ (\Gamma_1 - \Gamma_2)}}$ $I_0 = 2.2 \pm 1.0$ $\Gamma_1 = 2.26 \pm 0.03$ $\Gamma_2 = 2.63 \pm 0.07$ $ E_{{\rm B}} = 2.7 \pm 0.5 $ 15.1 (13) $84.6 \pm 38.5 $


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