Up: Telescope and other Devices
A simple thermoelectric infrared sky temperature sensor is mounted on the north west corner of dome. The voltage from the sensor (irvolts) and the case temperature (ovolts) are measured and then a relationship is derived to compute the aproximate cloud cover.
The field of view is about 60 degrees. And therefore does not give an all sky view. The sensor only responds to low level warm clouds and not cirrus.
The voltages are measured using the test points (see Figure 3.9).
Voltage Test Point Schematic