NORVIS: a portable broadband imaging spectrograph for auroral observations

Abstract. We present NORVIS (NORdlys Versatile Imaging Spectrograph), a portable broadband imaging spectrograph developed for ground-based auroral observations. Based on the Star'Ex optical concept, NORVIS is optimized for auroral emissions and covers approximately 380–860 nm in a single acquisition at a moderate spectral resolution of 1.2 nm FWHM. The instrument combines auroral spectroscopy, wide-field context imaging, field operation, automated spectral reduction, and centralized data archiving within a researcher-citizen science framework. First observations were obtained during a campaign at Skibotn Observatory, Norway, in February 2026, during which approximately 1200 spectra were acquired and reduced over three observing nights, with typical exposure times of 30 s. These observations demonstrate the simultaneous detection of key auroral emissions, including the N₂⁺ 1NG bands at 391.4 and 427.8 nm and the [O I] emissions at 557.7 and 630.0/636.4 nm, while also providing access to the Hα region and to O I emissions at 777.4 and 844.6 nm. Representative observations illustrate the potential of NORVIS for emission-ratio diagnostics and geometry-aware interpretation of auroral structures. NORVIS is intended to form the basis of a distributed observing network, with coordinated deployments planned in Kiruna, Skibotn, Svalbard, and northern Finland, followed by permanent installations at Kiruna, Skibotn, the Kjell Henriksen Observatory in Svalbard, and Nyrölä.