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

• Main Authors: Hosokawa, Keisuke, Ogawa, Yasunobu, Taguchi, Satoshi
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: figshare 2019
• Subjects: Biophysics; Space Science; 29999 Physical Sciences not elsewhere classified; FOS Physical sciences; Medicine; 59999 Environmental Sciences not elsewhere classified; FOS Earth and related environmental sciences; Svalbard; Longyearbyen; Norway
• Online Access: https://dx.doi.org/10.6084/m9.figshare.c.4729820.v1; https://springernature.figshare.com/collections/Imaging_of_polar_cap_patches_with_a_low-cost_airglow_camera_pilot_observations_in_Svalbard_Norway/4729820/1

Abstract We evaluate the capability of a low-cost all-sky imager (ASI), which has been operative in Longyearbyen (78.1° N, 15.5° E), Norway, to detect 630.0 nm airglow signatures of polar cap patches. The ASI is composed of a small camera, with a charge-coupled device (CCD), manufactured by Watec Co. Ltd., a fish-eye lens, and an optical filter whose central wavelength is 632.0 nm and full-width half maximum (FWHM) is 10 nm. In Longyearbyen, another ASI equipped with a cooled electron-multiplying charge-coupled device (EMCCD) camera has been operative for observations of polar cap patches. We compare the images from the two systems and investigate the performance of the low-cost ASI. On the night of December 4, 2013, a series of polar cap patches were observed by the EMCCD ASI. The low-cost ASI also detected regions of enhanced 630.0 nm airglow passing through the fields-of-view. The quality of the raw images from the low-cost ASI obtained every 4 s were visibly much worse than that of the EMCCD ASI. However, an integration of 7–15 consecutive images made it possible to capture the temporal evolution and spatial structure of the patches, for example, their anti-sunward propagation and finger-like structures along the trailing edge. The estimated values of the absolute optical intensity from the low-cost ASI were found to be consistent with those from the EMCCD ASI, whereby the offset was