Fig. 6

NIRAS measurements with the 150-lpmm grating at IRF, Kiruna on September 21, 2019. a Local K-index obtained from geomagnetic field observations at Kiruna. b and c are keograms along geomagnetic north–south and east–west directions, respectively. d Auroral intensity at a geographic zenith as a function of time e Dynamic spectrum from 1114 to 1624 nm obtained by the NIRAS. f \(\text {P}_1\)(2), \(\text {P}_1\)(3), and \(\text {P}_1\)(4) line intensities in OH (3,1) band as a function of time