Fig. 2.

Observed transitions of CH₃C₄H towards TMC-1. The abscissa corresponds to the rest frequency of the lines assuming a local standard of rest velocity of TMC-1 of 5.83 km s^–1. Line parameters for the observed transitions are given in Table A.1. The ordinate is the antenna temperature, corrected for atmospheric and telescope losses, in millikelvin. The red line shows the computed synthetic spectrum for this species for T_r=7 K and a column density of 6.5×10¹² cm^–2 for each of the A and E states of vinyl diacetylene.