NUV/Blue spectral observations of sprites in the 320-460 nm region: N2 (2PG) Emissions

A near-ultraviolet (NUV) spectrograph (320-460 nm) was flown on the EXL98 aircraft sprite observation campaign during July 1998. In this wavelength range video rate (60 fields/sec) spectrographic observations found the NUV/blue emissions to be predominantly N2(2PG). The negligible level of N2 (1NG) present in the spectrum is confirmed by observations of a coaligned, narrowly filtered 427.8 nm imager and is in agreement with previous ground-based filtered photometer observations. The synthetic spectral fit to the observations indicates a characteristic energy of ∼1.8 eV, in agreement with our other NUV observations.