Continuum image of W3 obtained at 7.24 GHz with the SRT. The field of view is about 2^o × 2^o. The RMS noise is ≃4 mJy/beam and the resolution is 2.6 arcmin (SRT beam size at 7.24 GHz). The color map has been saturated to highlight the low surface brightness emission. Inset spectrum: 6.7 GHz methanol maser emission (Jy) in W3OH is shown. The spectra were taken with XARCOS on January 28, 2016. Four sub-bands (see panels) were observed simultaneously at increasing spectral resolution. Specifically we show spectra with 1.4 km s^-1, 170, 40, and 10 m s^-1 channel widths (from top to bottom). Left and right circular polarizations have been averaged. The velocity scale refers to the LSR frame and uses the optical convention (for more details see Sect. 8).