North-eastern part of M 33 in the IRAC 8 μm band (Verley et al. 2007). The cloud we present here is in the small circle at the top center of the image, representing the primary beam of the Plateau de Bure interferometer at the frequency of CO(1–0). The “Lonely Cloud”, a fairly CO-strong inter-arm GMC (Gardan 2007; Braine et al. 2010a), is also indicated with a small circle. The small rectangle at Dec 30:52 and the small triangles forming an “X” in and around the rectangle indicate the individual positions of the [C ii] HIFI observations of the H ii region BCLMP 691 presented in Braine et al. (2012). The large lower rectangle shows the region around BCLMP 302 observed with PACS by Mookerjea et al. (2011). The center of M 33 is at the position of the triangle to the lower right of the image of M 33. The giant H ii region NGC 604 can be seen as the very bright region to the left around Dec 30:47 and is marked with a  × .