magnetic field of the jet is used to explain the lower frequency peak. Different scenarios within various models are used to explain the high-frequency peak: external Compton [@1989ApJ...340..162M; @1994ApJS...90..945D; @1994ApJ...421..153S] and synchrotron self-Compton [SSC, @1992MNRAS.258..657C; @1992ApJ...397L...5M] as leptonic models, proton synchrotron emission [@1996SSRv...75..331M; @2000NewA....5..377A; @2001APh....15..121M] and photo-pion production [@2014ApJ...797...89A] as hadronic models. Traditionally, in view of their relative simplicity and agreement with the data, single-zone SSC models have been used to describe BL Lac SEDs [e.g. @2011ApJ...727..129A; @2011ApJ...736..131A]. However, there is growing evidence that these models do not reproduce all the observed features of BL Lac objects , and, in some cases, more complicated models should be considered. BL Lac objects are classified according to the peak frequency of their lower energy peak, $\nu_{syn}$ [@1994MNRAS.268L..51G]: low synchrotron peaked (LSP; $\nu_{syn}<10^{14}$Hz), intermediate synchrotron peaked (ISP; $10^{14}\leq\nu_{syn}<10^{15}$Hz), and high synchrotron peaked (HSP; $\nu_{syn}\geq10^{15}$Hz) [@2010ApJ...716...30A].

S2 0109+22 (also known as GC 0109+224), at coordinates (J2000) $\text{RA = 01h12m05.8s}$ and $\text{DEC=+22d44m39s}$, was first detected as a compact radio source in the 5GHz Survey of the NRAO 43m dish of Green Bank, West Virginia [@1971AJ.....76..980D; @1972AJ.....77..265P]. In 1976, it was optically identified as a stellar object of magnitude 15.5 on the Palomar Sky Survey plates, 