Fig. 11
From: A new five-wavelength photometer operated in Tromsø (69.6°N, 19.2°E)
Spectra for the five emissions between 01:06:00 and 01:08:00 UT on October 20, 2017. The horizontal dashed lines denote the 99% significance level. The vertical dotted lines denote oscillations of 1/5, 1/9.1, 1/11, and 1/20 Hz (i.e., periods being 5, 9.1, 11, and 20 s, respectively). Closed (open) circles denote data whose values are greater (smaller) than the 99% significance level