However, there seems to be an increased flux in X-rays, optical and UV bands around the flare night, which suggests that emission in these bands could originate from a single region.

We compare the integral flux ($F_{>200\,\text{GeV}}$) of S2 0109+22 to that of other TeV BL Lac objects (21 sources) with variable flux in VHE gamma rays presented in the most recent population study by , who studied a time independent correlation between several lower-energy bands and VHE gamma-ray luminosity, and predicted the VHE gamma-ray flux for 182 non-TeV BL Lac objects. The comparison is shown in Figure \[histo2\]. Both the lowest and the largest observed flux of S2 0109+22 during the MAGIC campaign are among the faintest of the population. High and low state VHE gamma-ray predicted energy flux (&gt;200GeV) in are $(4.5\pm1.9)\times 10^{-12}$ and $(9.8\pm2.1)\times 10^{-14}$ergcm$^{-2}$s$^{-1}$, respectively. The largest observed flux over the same energy range, $F_{>200\,\text{GeV}}^{\text{high~obs}}=(4.6\pm1.5)\times 10^{-12}$ergcm$^{-2}$s$^{-1}$, is in good agreement with the predicted flux. The lowest observed flux of this source is $F_{(>200\,\text{GeV})}^{\text{low obs}}=(1.5\pm0.7)\times 10^{-12}$ergcm$^{-2}$s$^{-1}$. The observed VHE gamma-ray flux of the source is fainter than the sample of variable TeV BL Lacs.

Figure \[vhe\_sed\] shows the spectrum of S2 0109+22 in the VHE gamma rays. 