Weather station

The new Vaisala weather station is mounted on the same mast as the existing one. Data from the new station is now also saved in data base for comparison with old station data. There were some problems with the wind measurements of the new station, readings occasionally dropping to zero, and a fix has been incorporated in the reading program.

There were some discussions about the validity of the humidity measurements and the rules for closing the telescope when comparing the measurements to those from other telescopes and those from the Vaisala station. One issue is that the humidity meter of the Vaisala station has not been calibrated yet while we also do not know if, and in what way the meters at other telescopes have been calibrated. In general, for the rules for closing it is primarily important that they are well defined. The precise behavior of the meter is a different issue. As there is still the question if at times the humidity is lower than indicated (especially important when the temperature is below zero) and a proper hand held humidity meter was purchased.

The communication to the weather station has been changed from a copper `current-loop' serial link to a fibre optic Ethernet line. This new line accommodates both the old and new weather stations as well as a web cam. The change also removes a frequent problem of lightning strikes on the serial link which sometimes destroyed the transmitter and receiver devices.