About this spectrometer: This spectrometer measures the night sky spectrum and has the main purpose to allow for a real-time detecton of northern lights, specifically of the strong and destinctive 5577Å line. It observes the Northern suburban sky at Viby/Sollentuna near Stockholm/Sweden at heights between 12 and 48 degrees above the horizon. There is a fair amount of artificial background light, mostly by sodium vapor lamps and few mercury vapor lamps. Therefore the measurements do not represent the dark-sky spectrum. The spectrometer is based on a blaze transmission grating. The 300 grooves/mm grating is illuminated by a single slit. It is observed by a ZWO ASI120MM CMOS camera with a 16mm f/1.2 CS-mount lens. The spectrometer has been calibrated using several low-power lasers, and a daytime/twilight Fraunhofer-calibration is in preparation. Data acquisition and analysis is performed by a Raspberry Pi 3. The acquisition code is based on Thomas Jacquin's Wireless All Sky Camera project. The analysis code is self-developed and based on Mark Kness' Colorpy package. A full night's worth of data amounts to around 3.8 GiB of raw picture data (can be compressed losslessly to about 1 GiB), which are reduced on-line to around 120 MiB of spectral plots and 300 kiB of analytic spectral data. The spectrometer design is inspired by Michael Theusner's aurora monitor based in Northern Germany (Schiffdorf close to Bremerhaven). See here, here, and here for some pictures of the spectrometer. Please note: The spectrometer is operated sporadically only, when conditions are favorable for northern lights and local weather is favorable and local skies are reasonably clear.