SQM-LE or SQM-LU as a Clear Sky Detector

The following example graphs reveal how easy it is to identify clear skies using a Unihedron SQM-LE or SQM-LU recording readings once per minute. Clear skies are indicated by smooth segments of measurements and cloudy skies by rapidly changing values.

It is possible to sense the "churn" in real time and produce an alarm when a sufficient string of smooth recordings (fainter than some desired threshold) has occurred - indicating cleared skies.

The readings above were obtained in the town of Dundas, Ontario with an SQM-LE mounted on the roof of my house.

Doug Welch