centred on the MAGIC detection peak on MJD 57228 (2015 July 25). The data reduction of the events of the Pass8 source class was performed with the ScienceTools software package version v10r0p5[^2] in the energy range 0.1–300GeV. To reduce Earth limb contamination a zenith angle cut of 90$^{\circ}$ was applied to the data. The un-binned likelihood fit of the data was performed using the suggested Galactic diffuse-emission model and isotropic component [@2016ApJS..223...26A] recommended for Pass8 Source event class[^3].

The normalizations of both diffuse components in the source model were allowed to freely vary during the spectral fitting. The source model also includes the sources of the *Fermi*-LAT third source catalogue [3FGL, @2015ApJS..218...23A] within 25$^{\circ}$ of the source of interest. Spectral indices and fluxes are left to freely vary for sources within 5$^{\circ}$; fluxes are also left to freely vary for sources flagged as ’variable’ in the 3FGL catalogue that lie from 5 to 10$^{\circ}$. The spectral parameters of the sources from 10 to 25$^{\circ}$, were instead fixed to their catalogue value.

To construct the light-curve (LC) with 1-day time bins, only the source of interest (normalization and spectral index) and the diffuse models (normalization) were left free to vary, while 