Martin Jelinek (IAA CSIC Granada)
Martin Kakona (ICZ Ceske Budejovice)
Jan Strobl (MFF UK Praha)

% {} % context

While operating an independent robotic telescope, it is important to know
the sky transparency independently on operation of the telescope. 

% {} % aims 

We constructed a simple device, cloudmeter, based on a commercial radiative
thermometer available from Melexis. The device, with no moving parts, is
placed so that it has a permanent view of the sky.

% {} % methods 

We measure the effective temperature of the sky together with the local
temperature of the device. The temperature difference, as shown before by
many, may be used as an indicator of the cloud cover. 

% {} % results 

We show the corelation/dependency of the optical extinction coefficient on
the signal obtained by the cloudmeter. 

% {} % conclusions

Although on other sites the model constants may be distinct, the
cloudmeter, with it's simplicity and robustness is an interesting support
tool for robotic telescopes.