SNOWS: Sierra Nevada Observatory Weather System

摘要

The Observatorio de Sierra Nevada (OSN) is located at an altitude of 2800m at the Loma de Dilar in the Sierra Nevada mountain range, in the province of Granada, Spain. It is operated and maintained by the Instituto de Astrofisica de Andalucia (IAA-CSIC) and contains two Nasmyth telescopes with apertures of 1.5 and 0.9m and an Altazimuth telescope with an aperture of 0.6 m. Given that the quality of the images and, indeed, the performance of the instruments are influenced by weather conditions, it would appear that the existence of a weather station capable of producing accurate descriptions is an essential component of any observatory. This is particularly true, however, in our case where, given the altitude, weather conditions at certain times of the year are especially harsh. For this reason, our observatory has required the installation of a robust weather station with easily replaceable sensors which can provide accurate and reliable measures of wind, temperature and humidity. At the same time, in order to avoid a complex topology of unmanageably long wires due to the distribution of a large number of sensors around the buildings, domes telescope mirrors and instruments, it has been necessary to implement a distributed system with several independent nodes connected to a CAN bus. This system is now in operation and running automatically at the OSN and provides all the data from sensors to the observatory control systems and to internet users. This paper gives a detailed description of the SNOWS project, including the development of the weather station, the software and hardware architecture, and the use of distributed nodes with a linear serial bus. The paper also provides some results regarding the wind, temperature and humidity sensors employed at the OSN.