Equatorial ring model (white) of the ¹²CO and ¹³CO emission of NGC 6778 overlaid on an image of the nebula taken with the NOT telescope (adapted from Guerrero & Miranda 2012). White crosses mark the observed offset positions, while associated insets show their corresponding ¹²CO J = 2–1 emission profiles (black) and SHAPE+SHAPEMOL model synthetic profiles (red). The HPBW of the IRAM 30m telescope at the ¹²CO J = 2–1 transition is indicated by the white circle.