Manufactured by Unihedron, the Sky Quality Meter measures the brightness of the night sky in magnitude per square arcsecond. The chart shows day (zero values) and night (higher value = darker sky). Latest measurements on the right side. The 2 Megabyte PDF manual for the Sky Quality Meter is available by clicking here
The Sky Brightness Chart shows magnitude per square arcsecond (mpsas) related to the number of sky objects visible. A mpsas value of 17 would relate to street-light or moonlight brightness, a value of 19 would allow bright sky objects to be seen, a value of 21 to 23 relates to deep sky objects and 24 would be a practical maximum on a very dark sky night.
To access the raw CSV data files click HERE