Energy levels, transition frequencies and Einstein A coefficients for the vibrational ground state of HC₅N are based on Alexander et al (1976). Collisional rates are scaled HC₅N-He rates from Bop & Lique (2025) and cover temperatures in the range from 5 to 50 K including energy levels up to J=46 for collisions with H₂.

The second datafile provides higher accuracy for the lowest 26 rotational states of HC₅N and is recommended for temperatures below 15 K.