Selected lines of ²⁹SiC₂ observed with the new FTS spectrometers installed in the IRAM 30 m telescope after 2010. Red lines show the fit to the observed rotational transitions. The quantum numbers of each transition are indicated at the top-right corner of each panel. Vertical red arrows indicate the fitted frequencies for these transitions. Features from other species are indicated in blue. The sharp edges of the ²⁹SiC₂ line profiles allow to derive accurate frequencies for these rotational transitions. Measured and fitted frequencies for this isotopologue of SiC₂ are given in Table A.5.