Characterising and correcting atmospheric seeing effects in astronomy

Lead Research Organisation: Durham University
Department Name: Physics

Abstract

The optical effects of atmospheric turbulence, known as 'seeing', are a major limitation for ground--based optical astronomy. Seeing reduces the image resolution that can be achieved with large telescopes and adds noise to photometric measurements. One of the key areas of instrumentation development for astronomy is currently the use of adaptive optical (AO) systems to correct the effects of seeing and improve image resolution in real time. The successful development and application of AO technology is critical to the science programs of modern large telescopes such as the ESO VLT and the planned European ELT. The Centre for Advanced Instrumentation (CfAI) Durham is centrally involved in the development of complex AO systems for large telescopes.
One of the main methods for study of extrasolar planets is via photometric measurement of transit light curves, i.e. the dip in brightness observed when a planet transits in front of its parent star as seen from Earth. Transit depths are typically small (less than 1\% dip in brightness), so that very high photometric accuracy is essential. The photometric effects of atmospheric seeing ('scintillation') are a limiting factor for ground--based observations of exoplanet transits. CfAI is developing methods to characterise and reduce the effects of seeing and scintillation for exoplanet transit measurements, and for similar high time-resolution observations from the ground.
In the frame of these developments in instrumentation to combat the effects of seeing, achieving a good understanding of the properties of atmospheric turbulence at observatory sites is of increasing importance. CfAI is leading campaigns to characterize the seeing at the VLT observatory at Paranal, Chile, and the ORM observatory at La Palma. This research project will engage in the development, deployment and exploitation of site--testing instruments at the observatory sites, to improve our understanding of seeing and its effects on astronomical telescope observations. The student will also look to apply these results to improve the performance of AO and/or scintillation correction systems at the telescope, and/or to the forecasting of optical turbulence conditions at observatory sites.

Publications

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Farley O (2018) Representative optical turbulence profiles for ESO Paranal by hierarchical clustering in Monthly Notices of the Royal Astronomical Society

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Osborn J (2018) Optical turbulence profiling with Stereo-SCIDAR for VLT and ELT in Monthly Notices of the Royal Astronomical Society

Studentship Projects

Project Reference Relationship Related To Start End Student Name
ST/N50404X/1 01/10/2015 30/09/2020
1738781 Studentship ST/N50404X/1 01/10/2016 31/03/2020 Oliver Farley