A^3^{Pi}-X^3^{Sigma}^-^ transitions of OH+

Submillimeter and ultraviolet observations rely on high quality laboratory spectra. Recent measurements of the fundamental vibrational band and previously unanalyzed Fourier transform spectra of the near-ultraviolet A^3^{Pi}-X^3^{Sigma}^-^ electronic spectrum, acquired at the National Solar Observatory (NSO) at Kitt Peak in 1989, provide an excellent opportunity to perform a global fit of the available data.

These new optical data are approximately four times more precise as compared to the previous values. The fit to the new data provides updated molecular constants, which are necessary to predict the OH^+^ transition frequencies accurately to support future observations. These new constants are the first published using the modern effective Hamiltonian for a linear molecule.