Spectra of TMC-1 in the Q band at the frequencies of the most favorable lines of E-1-cyano-1,3-butadiene. The noise level, as measured in a window of ± 8 MHz around the expected position of each line with the nominal spectral resolution of 38.15 kHz, is indicated by a gray horizontal band. The red lines correspond to the line intensities calculated adopting as column density for E-1-cyano-1,3-butadiene the 3 σ upper limit of 1.2 × 10¹⁰ cm⁻² determined here, while the blue dashed lines correspond to the line intensities calculated adopting as column density the value of 3.8 × 10¹⁰ cm⁻² determined by Cooke et al. (2023). Our data is clearly inconsistent with such a column density.