Top: local thermodynamic equilibrium model spectrum of benzonitrile in the DSS-43 frequency range for a temperature of 8.5 K. Line intensities are normalized to the 18.41 GHz transitions. Transitions above the green horizontal lines are included in the stacking analysis. Bottom: stacked spectra of benzonitrile toward Cha-MMS1 and Cha-C2 normalized to the 18.41 GHz line. The green curves are 3σ upper limit LTE models corresponding to column densities reported in Table 4.