A. Eff-Darwich

Adaptive optics parameters connection to wind speed at the Teide Observatory

Current projects for large telescopes demand a proper knowledge of atmospheric turbulence to design efficient adaptive optics systems in order t reach large Strehl ratios. However, the proper characterization of the turbulence above a particular site requires long-term monitoring. Due to the lack of long-term information on turbulence, highaltitude winds (in particular winds at the 200 mbar pressure level) were proposed as a parameter for estimating the total turbulence at a particular site, with the advantage of records of winds going back several decades. We present the first complete study of atmospheric adaptive optics parameters above the Teide Observatory (Canary Islands, Spain) in relation to wind speed. On-site measurements of C 2 N (h) profiles (more than 20200 turbulence profiles) from G-SCIDAR observations and wind vertical profiles from balloons have been used to calculate the seeing, the isoplanatic angle and the coherence time. The connection of these parameters to wind speeds at ground and 200 mbar pressure level are shown and discussed. Our results confirm the well-known high quality of the Canary Islands astronomical observatories. The presence of optical turbulence in the Earth’s atmosphere drastically affects ground-based astronomical observations. The wavefront of the light coming from astronomical objects is distorted when passing through the turbulence layers, the wavefront being aleatory when reaching the entrance pupil of telescopes. The result is a degradation of the angular resolution of ground-based astronomical instruments. Several techniques have been developed to compensate for the effects of the atmosphere on astronomical images trying to reach the diffraction limit, the most popular being adaptive optics (AO hereafter) systems. The larger the telescope diameter, the more difficult the proper correction of the atmospheric turbulence becomes. The excellent image quality requirements of current large and future extremely large telescopes needs the design of adaptive optic systems with the capacity of adaptability to the prevailing turbulence conditions at the observing site. A proper knowledge of the statistical behaviour of the parameters describing the atmospheric turbulence at any site is crucial for the design of efficient systems. There are three basic parameters relevant to AO design and operation: Fried’s parameter (r0), the isoplanatic angle (�0), and the coherence time (�0). These

Infrared astronomical characteristics of the Roque de los Muchachos Observatory: precipitable water vapour statistics

We present measurements of the atmospheric water vapour content above the Roque de los Muchachos Observatory (ORM) obtained using the Global Positioning System (GPS). The GPS measurements have been evaluated by comparison with 940-nm radiometer observations. A statistical analysis of the GPS measurements points to the ORM as an observing site with suitable conditions for infrared observations, with a median column of precipitable water vapour (PWV) of 3.8 mm. PWV presents a clear seasonal behaviour, with winter and spring being the best seasons for infrared observations. The percentage of nights showing PWV values less than 3 mm is over 60 per cent in February, March and April. We have also estimated the temporal variability of water vapour content at the ORM. We present a summary of PWV statistical results at different astronomical sites, noting that these values are not directly comparable as a result of the differences in the techniques used to recorded the data.

Comparative analysis of the impact of geological activity on the structural design of telescope facilities in the Canary Islands, Hawaii and Chile

An analysis of the impact of seismic and volcanic activity has been carried out at selected astronomical sites, namely the observatories of El Teide (Tenerife, Canary Islands), Roque de los Muchachos (La Palma, Canary Islands), Mauna Kea (Hawaii) and Paranal (Chile), and the candidate site of Cerro Ventarrones (Chile). Hazard associated with volcanic activity is low or negligible at all sites, whereas seismic hazard is very high in Chile and Hawaii. The lowest geological hazard in both seismic and volcanic activity is found at Roque de los Muchachos observatory, on the island of La Palma.

Comparative analysis of the impact of geological activity on the structural design of telescope facilities in the Canary Islands, Hawaii and Chile: Geological activity at astronomical sites

An analysis of the impact of seismic and volcanic activity has been carried out at selected astronomical sites, namely the observatories of El Teide (Tenerife, Canary Islands), Roque de los Muchachos (La Palma, Canary Islands), Mauna Kea (Hawaii) and Paranal (Chile), and the candidate site of Cerro Ventarrones (Chile). Hazard associated with volcanic activity is low or negligible at all sites, whereas seismic hazard is very high in Chile and Hawaii. The lowest geological hazard in both seismic and volcanic activity is found at Roque de los Muchachos observatory, on the island of La Palma.

Comparative analysis of the impact of geological activity on astronomical sites of the Canary Islands, Hawaii and Chile

An analysis of the impact of seismic and volcanic activity has been carried out at selected astronomical sites, namely the observatories of El Teide (Tenerife, Canary Islands), Roque de los Muchachos (La Palma, Canary Islands), Mauna Kea (Hawaii) and Paranal (Chile), and the candidate site of Cerro Ventarrones (Chile). Hazard associated with volcanic activity is low or negligible at all sites, whereas seismic hazard is very high in Chile and Hawaii. The lowest geological hazard in both seismic and volcanic activity is found at Roque de los Muchachos observatory, on the island of La Palma.