AO4ELT5 Proceedings

PSF reconstruction via full turbulence characterization and end-to-end simulations

Béchet, Clémentine (Engineering School, Pontificia Universidad Católica de Chile, Santiago, Chile), Ayancán, Boris (Engineering School, Pontificia Universidad Católica de Chile, Santiago, Chile), Guesalaga, Andrés (Engineering School, Pontificia Universidad Católica de Chile, Santiago, Chile), Correia, Carlos (Laboratoire d’Astrophysique de Marseille, Marseille, France), Neichel, Benoit (Laboratoire d’Astrophysique de Marseille, Marseille, France), Masciadri, Elena (INAF - Arcetri Astrophyisical Observatory, Florence, Italy), Conan, Rodolphe (Giant Magellan Telescope Corporation, Pasadena, USA)

Enhancement and wise archiving of astronomical images require an accurate estimate of the observational Point Spread Function (PSF). Although modelling of the telescope and its optics is a well-understood problem, PSF reconstruction becomes challenging when the observations include adaptive optics (AO) correction. The approach presented in this paper consists in feeding an end-to-end (E2E) simulation of the telescope, the instrument and its environment with the characterized disturbances from the telemetry and AO loop data, in order to produce the estimated PSFs. This method benefits from the developments made in the last years with respect to the estimation of external disturbances during AO correction, such as turbulence profile and its dynamics as well as sensor noise and vibrations characteristics. In particular, characterization of the turbulence profile in terms of strength, Cn2(h), and outer scale, L0(h), is considered with an example on on-sky recorded AO telemetry from the GALACSI AO system. Once identified, the internal and external parameters of the observing conditions are used as inputs to carry out E2E simulations of the optical propagation and estimate the PSF. The method can be regarded as a ”brute force” approach, as it is highly intensive in computer power; particularly for the ELTs. However, its ability to integrate complex combination of effects from all disturbances and not relying on analytical approximations for the aliasing or fitting errors makes the approach worth of a deeper study. E2E simulations have been used before in PSF reconstruction, but limited to a theoretical modelling of the system. Here, the development of the E2E simulation part is an ongoing work. A simplified AO system similar to the GALACSI WFM is currently simulated to obtain the PSF estimates and illustrate how such approach allows to account for the anisoplanatic effects and for the influence of the outer scale values.

DOI: 10.26698/AO4ELT5.0051- Proceeding PDF

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