Fig. 2From: Observations of equatorial plasma bubbles using a low-cost 630.0-nm all-sky imager in Ishigaki Island, JapanAll-sky 630.0-nm images obtained at 2330 JST on February 14, 2015: a raw all-sky image obtained with an exposure time of 4 s; b average of 20 consecutive images (total integration time of 80 s); c average of 30 consecutive images (total integration time of 120 s); d average of 40 consecutive images (total integration time of 160 s)Back to article page