Fig. 12
From: A new five-wavelength photometer operated in Tromsø (69.6°N, 19.2°E)
Spectra for the five emissions between 01:30:00 and 02:00:00 UT on October 20, 2017. The horizontal dashed lines denote the 99% significance level. The vertical dotted lines denote oscillations of 1/200 and 1/225 Hz (i.e., periods being 200 and 225 s, respectively). Closed (open) circles denote data whose values are greater (smaller) than the 99% significance level