High accuracy spectroscopic parameters of the 1.27 µm band of O2 measured with comb-referenced, cavity ring-down spectroscopy

•High-precision, low-uncertainty CRDS measurements of 1.27 µm air-broadened O2 band line with frequency axis linked to Cs clock.•New line list reported using Dicke-narrowing constrained Hartmann-Tran profile.•Multi-spectrum line shape analysis and Monte Carlo model indicates strong numerical correlation between Dicke narrowing and speed dependent narrowing mechanisms.•Intensities and broadening coefficients measured with relative uncertainties of 0.15 % and 0.05 %, respectively and line positions measured with 60 kHz uncertainty.•Measurements values of binary absorption coefficients for collision induced absorption spectrum in sub-percent-level agreement with prior work.