Some meteorological parameters affecting the image quality of the William Herschel telescope on La Palma

Abstract

Understanding of the factors which limit the image quality of a ground based telescope is still an interesting challenge despite the effort devoted to the problem since the early days of optical astronomy. At the Roque de los Muchachos observatory, on the island of La Palma (Canary Islands) this problem has been studied as part of a programme aimed to improve the optical performance of the biggest instrument at the observatory, the anglo-dutch William Herschel Telescope. The programme comprises a range of studies to investigate the possible factors deteriorating the image quality at the telescope. This thesis forms part of the meteorological studies of this programme and it is based on the data collected by a meteorological station recently installed at the observatory. In particular, phenomena such as wind direction, wind speed, pointing direction of the telescope dome relative to the wind direction, air and soil temperatures, relative internal/external temperatures, barometric pressure and humidity have been investigated and the relationship between these and the image quality at the telescope has been analyzed. The image quality is found to be particularly sensitive to the wind direction and the internal differences in temperatures. The season of the year also seems to have an influence on the image quality. In the conclusions, suggested further avenues of investigation are given.