Development of low-cost multi-wavelength imager system for studies of aurora and airglow

Abstract

This paper introduces a new system that can monitor auroras and atmospheric airglows using a low-cost Watec monochromatic imager (WMI) equipped with a sensitive camera, a filter with high transmittance, and the optics which do not make parallel ray paths. The WMI system with 486-nm, 558-nm, and 630-nm band-pass filters has observable luminosity of about ~200-4000 Rayleigh for 1.07-sec exposure time and about ~40-1200 Rayleigh for 4.27-sec exposure time, for example. It is demonstrated that the WMI system is capable of detecting 428-nm auroral intensities properly, through comparison with those measured with a collocated electron-multiplying charge-coupled device (EMCCD) imager system with narrower band-pass filter. The WMI system has two distinct advantages over the existing system: One makes it possible to reduce overall costs, and the other is that it enables the continuous observation even under twilight and moonlight conditions. Since 2013 a set of multi-wavelength WMIs has been operating in northern Scandinavia, Svalbard, and Antarctica to study meso-and large-scale aurora and airglow phenomena. Future development of the low-cost WMI system is expected to provide a great opportunity for constructing a global network for multi-wavelength aurora and airglow monitoring.

First Simultaneous Lidar Observations of Thermosphere‐Ionosphere Fe and Na (TIFe and TINa) Layers at McMurdo (77.84°S, 166.67°E), Antarctica With Concurrent Measurements of Aurora Activity, Enhanced Ionization Layers, and Converging Electric Field

“…Therefore, we investigate concurrent observations of aurora and ionization. A collocated auroral all‐sky camera at Arrival Heights (Ogawa et al, 2020) observed the auroral activity using the oxygen green line at 557.7 nm every 4 s. A keogram of the auroral image in the north‐south direction is plotted versus time in Figure 3a. Almost every distinct TIFe layer above ~115 km (Figure 3b) corresponds to an auroral event, which is reflected in enhanced green line emissions.…”

An Ephemeral Red Arc Appeared at 68° MLat at a Pseudo Breakup During Geomagnetically Quiet Conditions

“…Images from all‐sky cameras at Longyearbyen (Norway, geographic coordinates 78.15°N, 16.03°E; 557.7 nm), Abisko (Sweden, geographic coordinates 68.36°N, 18.82°E; 557.7 and 630.0 nm), Kilpisjärvi (Finland, geographic coordinates 69.05°N, 20.78°E; 557.7 and 630.0 nm), and Lovozero (Russia, geographic 67.97°N, 35.08°E; 557.7 nm) were investigated in this study, and carefully selected images and results will be presented in the article. The camera at Longyearbyen is mounted with a low‐cost Watec monochromatic sensor with an optical band‐pass filter of 557.7 nm and an all‐sky lens (Ogawa et al, 2020). The exposure time is 1 s. The cameras at Abisko and Kilpisjärvi belong to the Magnetometers Ionospheric Radars All‐sky Cameras Large Experiment (MIRACLE) camera network (Sangalli et al, 2011).…”

Imaging of polar cap patches with a low-cost airglow camera: pilot observations in Svalbard, Norway

“…The WATEC ASI is operative when the sun is below the horizon, even during the full moon period. The technical details of the WATEC ASI system, including the photos of the ASI system, are fully detailed by Ogawa (2019). The cost of the entire WATEC system is ~ 1000 USD, which is approximately 1% of that of the large cooled CCD ASI system.…”

“…As the incident angle increases, the transmission region shifts to the shorter wavelength, while the shape of the transmittance band does not change significantly. As described in Ogawa (2019), the incident angles of the ray path are mostly within about 18 deg. The use of relative wider pass-band filter allows us to observe the 630.0 nm emission even when the incident angle reaches this value (i.e., 18°).…”