Peak flux of the detected CO lines (full orange circles if S/N > 4.0, and purple if S/N ≤ 4.0) as a function of the integration time. The line rms is also shown (black triangles) and connected to the corresponding measured flux by a dotted vertical line. The expected trend of rms_line with the integration time is shown as dashed green line and the detection threshold of 4 × rms_line as dotted green line. The rms_line varies with channel width and depends on the line width.