ExoMol molecular line lists – XXXVII. Spectra of acetylene

A new ro-vibrational line list for the ground electronic state of the main isotopologue of acetylene,
¹²
C
2
H
2
, is computed as part of the ExoMol project. The aCeTY line list covers the transition wavenumbers up to 10 000 cm
⁻¹
(λ > 1 
$\mu$
m), with lower and upper energy levels up to 12 000 and 22 000 cm
⁻¹
considered, respectively. The calculations are performed up to a maximum value for the vibrational angular momentum, K
max
= L
max
= 16, and maximum rotational angular momentum, J = 99. Higher values of J were not within the specified wavenumber window. The aCeTY line list is considered to be complete up to 2200 K, making it suitable for use in characterizing high-temperature exoplanet or cool stellar atmospheres. Einstein-A coefficients, which can directly be used to calculate intensities at a particular temperature, are computed for 4.3 billion (4 347 381 911) transitions between 5 million (5 160 803) energy levels. We make comparisons against other available data for
¹²
C
2
H
2
, and demonstrate this to be the most complete line list available. The line list is available in electronic form from the online CDS and ExoMol data bases.