Intensity of the first negative band system of nitrogen in the night sky over Arecibo

Abstract

The 0–1 band (4278 A) of the first negative system of nitrogen has been measured in the spectrum of the night sky with a 1-m Ebert-Fastie spectrophotometer at the Arecibo Observatory. Integration periods of approximately 4 hours were needed to provide an adequate ratio of signal to noise. The measured spectra were corrected for blending with the 2–9 Herzberg band of oxygen at 4281 A. The intensity of the 4278-A radiation measured on 6 nights in late March 1976 was about 0.1 R. Little variation in the intensity was observed from night to night. We suggest that most of the observed emission was produced not by charged particle bombardment of the atmosphere but by photoionization of N2 by scattered solar radiation at 304 and 584 A.