Upper panel: K-band spectrum of SSC B1, obtained from aperture photometry based on the Brγ line. Ionized gas lines are the brightest lines across the spectrum. We mark the position of the H₂ rovibrational lines with short red lines. Lower panels: zoom in the H₂ 1−0 S(1) and Brγ lines. Red lines represent the fitted Gaussian curves to each line, and residuals are plotted in the bottom part. Table 3 lists the parameters of the Gaussian fits.