Near-ultraviolet and 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 and blue emissions to be predominantly N-2 (2PG). The negligible level of N-2 + (1NG) present in the spectrum is confirmed by observations of a co-aligned, 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 similar to 1.8 eV, in agreement with our other NUV observations.