Fig. (11) G57.2+0.8 spectra: The top panels show H I emission spectra: source spectrum (black), background spectrum (red) and difference (blue). The bottom panel gives the H I absorption spectrum (blue), the ¹³CO source spectrum (green) and the ¹³CO background spectrum (black). The dashed line is the ±2σ noise level of the H I absorption spectrum. The URC tangent point velocity is +38.3 km s^-1 and distance is 4.5 kpc.