PePSS - A portable sky scanner for measuring extremely low night-sky brightness

Highlights: • A sky scanner for measuring extremely low night-sky brightness has been developed. • The device is well suited for a narrow-band dark sky spectroradiometry. • The scanner benefits from fast readout, high dynamic range, and tunable sensitivity. • The spectral radiance characterizes spectral power distribution with high accuracy. • The minimum detectable signal threshold is a few µcd⋅m⁻² (airglow level). A new portable sky scanner designed for low-light-level detection at night is developed and employed in night sky brightness measurements in a rural region. The fast readout, adjustable sensitivity and linear response guaranteed in 5–6 orders of magnitude makes the device well suited for narrow-band photometry in both dark areas and bright urban and suburban environments. Quasi-monochromatic night-sky brightness data are advantageous in the accurate characterization of spectral power distribution of scattered and emitted light and, also allows for the possibility to retrieve light output patterns from whole-city light sources. The sky scanner can operate in both night and day regimes, taking advantage of the complementarity of both radiance data types. Due to its inherent very high sensitivity the photomultiplier tube could be used in night sky radiometry, while the spectrometer-equipped system component capable of detecting elevated intensities is used in daylight monitoring. Daylight is a source of information on atmospheric optical properties that in turn are necessary in processing night sky radiances. We believe that the sky scanner has the potential to revolutionize night-sky monitoring systems.