A fisheye lens and DSLR camera were used to investigate the natural and human-influenced changes in sky brightness over the night and seasons, and the correlation between sky brightness and loggerhead turtle activity. The sky brightness was quantified through calculations of visual magnitude of the zenith zone (0°-30° altitude) for locations selected around SEQ.
'Base' locations were chosen as they were separated from nearby artificial light. The results of the artificial light at night (ALAN) survey demonstrated a change in sky brightness throughout the night of approximately 0.2 mag/arcsec² (between 20:00 and 02:30), with the darkest skies around midnight.
In developed areas, the natural sky brightness cycle is impacted by human activity. The contributions of temporary lighting and maintained lighting were isolated during the analysis process. Temporary lighting includes vehicles, residential and commercial lighting, and maintained lighting includes streetlights, shop facades, unit block stairwells/common areas, and other sources which remain on throughout the night.
The sky brightness at a reference location demonstrated a change in sky brightness throughout the year of approximately 0.4 mag/arcsec², with darkest skies in winter.
Sky brightness is correlated with loggerhead turtle behaviour data to better understand the impacts of artificial light on nesting activity.