Integrated-intensity map of the JCMT ¹²CO J = 3–2 line in the velocity range +80− +110 km s⁻¹, which is the velocity range of the re-formed CO gas proposed by Koo & Moon (1997b), overlaid with orange contours of the VGPS 1.4 GHz radio continuum (the levels are 50–250 K in steps of 50 K). The two white crosses show the 1720 MHz OH masers discovered by Green et al. (1997). The white arrow points to the geometric center of W51C recorded in the Green SNR catalog (Green 2019). The white box shows the molecular clump toward which we conducted the Yebes 40 m observation.