Spectra of CO J = 2–1 in Zw 049.057. Top: integrated over the region with emission stronger than 3σ in the integrated intensity map. Bottom: extracted from the peak of the integrated intensity map. The shaded regions indicate the velocity intervals of the blue- and red-shifted line wings seen in the lower spectrum. A dashed line in each spectrum indicates the 1σ level of the noise above zero intensity. The spectra are referenced to the barycentric reference frame using z = 0.012999.