Synthetic spectra for auroral studies: The N₂ Vegard‐Kaplan Band System

Synthetic spectra of the N 2 Vegard‐Kaplan system are given for general reference. The material contains the spectrum across the entire range of emission (1500–6500 Å) calculated for auroral conditions and three typical resolutions (3.5, 10, and 25 Å); also included are individual band profiles calculated for 300–5000°K rotational temperature and 0–5 Å spectral halfwidth. For the auroral conditions a rotational temperature of 800°K is assumed; the vibrational populations are inferred from matching synthetic spectra and various published data. The calculations suggest a weak Vegard‐Kaplan auroral contribution in the 1500–2000 Å region of the far ultraviolet where the N 2 Lyman‐Birge‐Hopfield system is the dominant feature. Simulation of Vegard‐Kaplan emission from nitrogen trapped in a frozen argon matrix at 4.2°K is included as an example of a more unusual source.