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Table 1.

Summary of the variability study with IACT data, estimated from their joint fit with the exponentially cut-off power law model.

Name χ2 Fvar Npoints Scale
H.E.S.S. 22.0 0.31 ± 0.04 8 0.85 ± 0.23
MAGIC 16.7 0.43 ± 0.07 5 1.00 (fixed)
VERITAS 8.6 0.35 ± 0.11 3 1.27 ± 0.18

Notes. Fvar denotes the fractional variability (Edelson et al. 2002), Npoints is the corresponding light curve points counts, ‘Scale’ represents the scaling parameter applied to the flux values in order to account for the possible inter-instrument systematics (arbitrarily fixed to unity for MAGIC data). The best-fit spectral parameters were log10A = −22.51 ± 0.24 dex(1/(eV cm2 s)), Γ = 1.25 ± 0.29, E0 = 100 GeV, and log10Ecut = 13.99 ± 1.50 dex(eV). It should be noted that these parameters were determined without accounting for the measured source spectral energy distribution shape (using only flux measurements in the corresponding energy bins), and thus differ from those used in the cascade emission modelling that was further performed. See Sect. 3.1 for details.

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