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Abstract The hyperspectral camera for auroral imaging (HySCAI), which can provide a two-dimensional (2D) aurora image with full spectrum, was developed to study auroral physics. HySCAI consists of an all-sky lens, monitor camera, galvanometer scanner, grating spectrograph, and electron multiplying charge coupled device (EM-CCD). The galvanometer scanner can scan a slit image of the spectrograph on the all-sky image plane in the direction perpendicular to the slit. HySCAI has two gratings; one is 500 grooves/mm for a wide spectral coverage of 400–800 nm with a spectral resolution (FWHM) of 2. 1 nm, and the other is 1500 grooves/mm for a higher spectral resolution of 0. 73 nm with a narrower spectral coverage of 123 nm. The absolute sensitivity is 2. 1 count/s/R with 4 × 4 binning (256 × 340 image) at 557. 7 nm. The exposure time depends on the brightness of the aurora emission and is typically 64 s for a 2D image (0. 2 s per line scan). This system has been installed at the KEOPS (Kiruna Esrange Optical Platform Site) of the SSC (Swedish Space Corporation) in Kiruna, Sweden. All-sky images with a liquid crystal filter and a sky color camera have also been installed to compensate for the poor time resolution of HySCAI. 2D aurora monochromatic images for given wavelength are obtained by reconstructing the EM-CCD image over the scan period. HySCAI has the advantage of providing a 2D image of intensity for a weak emission line, which appears on top of a high background emission without the contamination from other emissions, which is usually difficult in a system with a bandpass filter. As the first light results, monochromatic images of N₂^+ N 2 + 1NG (0, 1) (427. 8 nm), N₂^+ N 2 + 1NG (0, 2) (470. 9 nm), H H β (486. 1 nm), N II (500. 1 nm), N I (² 2 D) (520. 0 nm), O I (¹ 1 S) (557. 7 nm, ), NaD (589. 3 nm), O I (¹ 1 D) (630. 0 nm), and N₂^+ N 2 + 1NG (670. 5 nm) emission intensity were measured. We estimated the precipitating electron energy from a ratio of I (630. 0 nm) /I (427. 8 nm) to be 1. 6 keV. Graphical Abstract
Yoshinuma et al. (Fri,) studied this question.