Extended Data Table 1 Comparison1 of natural night skies with stimulus night skies

From: Bogong moths use a stellar compass for long-distance navigation at night

  1. 1. To compare the background brightness of the natural starry night sky with those of the starry sky stimuli presented in the behavioural rig (natural and randomized), we used a Sky Quality meter (SQM; Unihedron, Sky Quality meter with lens, Version L). All measurements were made in autumn 2019. The natural sky measurement was done at 21:30 on a hill behind the laboratory at Glenhare on a clear moonless night. Measurements were made by pointing the SQM (at 60° to vertical) towards the starry sky in the four cardinal directions. The same procedure was repeated within the behavioural arena, by pointing the SQM towards the projection of the starry sky on the screen. Higher values (magnitudes/arcsec²) indicate lower background brightness and higher stellar contrast (i.e. a greater visibility of stars and lower light pollution). On the Bortle scale (en.wikipedia.org/wiki/Bortle_scale), the highest value on the scale – 22 – indicates the brightest stars seen against the darkest possible skies (e.g. a desert sky far from human civilisation). Values between 19.1–21.3 correspond to the brightness of the stars in suburban to rural/suburban transition areas (i.e. skies still very dark and stars highly visible, but with some background influence from human lighting).
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