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I recently experimented with one of those hand-held temperature measuring guns (laser-guided) and was interested to see how sensitive it was to the degree of cloud cover. In a sky with about 25% cover (scattered), I could easily pin-point the clouds just by looking at the temperature, which would vary between +5 deg C when aimed at a cloud and -30 deg C when on clear sky.
I then thought that it may not be too difficult to make a crude cloud detector by feeding the output of two IR detectors into a differential amplifier. ( I have not tried this yet.) One detector points towards the ground, and the other skyward. When the output of the amp exceeds a certain value, the sky could be judged to be clear in the direction of the skyward-pointing detector. I guess that this latter detector could even be mounted on the telescope and be set up so that when the amp output fell below a certain value, the sky could be judged to be cloudy and any imaging could be stopped.
Just a thought!
Cheers, Chris
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