HCN J(1−0) line observed in comet 29P with the IRAM 30 m telescope, averaging 2007 to 2011 data. A Gaussian fit to the F(2−1) main hyperfine component is shown by the red line. The Gaussian curves centered at the velocity of the F(0−1) and F(1−1) were rescaled assuming statistical weight ratios. The vertical scale is the main-beam brightness temperature. The velocity scale is in the comet rest frame. The spectral resolution is 66 m s⁻¹.