6.7 GHz CH₃OH masers detected over three epochs with the European VLBI Network (EVN), overlaid on the uniformly-weighted image of the 1.3 cm continuum observed with the VLA A-Array in December 1992 (Moscadelli & Goddi 2014). Colored dots show the absolute position of individual maser features, with colors denoting the maser V_LSR according to the color-velocity conversion code reported on the right side of the panel. The dot area is proportional to the logarithm of the maser intensity. The 1.3 cm map (dotted contours) was produced using archival data (VLA exp. code: AG360) originally reported by Gaume et al. (1995). Plotted contours are 7, 10 to 90% (in steps of 10%), and 95% of the map peak equal to 0.022 Jy beam⁻¹. The 1σ rms noise is ≈0.4 mJy beam⁻¹. Dashed arrows point to the main 1.3 cm continuum peaks, which are named following the notation by Gaume et al. (1995). The beam of the VLA-A 1.3 cm observations is reported in the inset in the bottom left of the panel. Absolute positions are relative to the epoch March 2, 2017, which is the first of the four VLBA epochs of the BM454 22 GHz maser observations (see Sect. 2.1). The two dashed lines indicate the major axes of the elongated distributions of 6.7 GHz masers in the northern and southern cores, and the two black-yellow stars labeled IRS1a and IRS1b mark the YSO positions determined by modeling the maser kinematics with edge-on disks in centrifugal equilibrium (Moscadelli & Goddi 2014). After Moscadelli & Goddi (2014), a third YSO, labeled IRS1c, is responsible for the excitation of the continuum and 6.7 GHz maser emission in the southern spherical region.