Here we describe a simple, efficient, and most importantly fully operational point-spread-function(PSF)-reconstruction approach for laser-assisted ground layer adaptive optics (GLAO) in the frame of the Multi Unit Spectroscopic Explorer (MUSE) Wide Field Mode. Based on clear astrophysical requirements derived by the MUSE team and using the functionality of the current ESO Adaptive Optics Facility we aim to develop an operational PSF-reconstruction (PSFR) algorithm and test it both in simulations and using on-sky data. The PSFR approach is based on a Fourier description of the GLAO correction to which the specific instrumental effects of MUSE Wide Field Mode (pixel size, internal aberrations, etc.) have been added. It was first thoroughly validated with full end-to-end simulations. Sensitivity to the main atmospheric and AO system parameters was analysed and the code was re-optimised to account for the sensitivity found. Finally, the optimised algorithm was tested and commissioned using more than one year of on-sky MUSE data. We demonstrate with an on-sky data analysis that our algorithm meets all the requirements imposed by the MUSE scientists, namely an accuracy better than a few percent on the critical PSF parameters including full width at half maximum and global PSF shape through the kurtosis parameter of a Moffat function. The PSFR algorithm is publicly available and is used routinely to assess the MUSE image quality for each observation. It can be included in any post-processing activity which requires knowledge of the PSF.
MUSE, a 2nd generation VLT instrument, will become the world's largest integral field spectrograph. It will be an AO assisted instrument which, in a single exposure, covers the wavelength range from 465 to 930 nm with an average resolution of 3000 over a field of view of 1'x1' with 0.2'' spatial sampling. Both the complexity and the rate of the data are a challenge for the data processing of this instrument. We will give an overview of the data processing scheme that has been designed for MUSE. Specifically, we will use only a single resampling step from the raw data to the reduced data produc…
MUSE, the Multi Unit Spectroscopic Explorer, is a 2nd generation integral-field spectrograph under final assembly to see first light at the Very Large Telescope in 2013. By capturing ~ 90000 optical spectra in a single exposure, MUSE represents a challenge for data reduction and analysis. We summarise here the main features of the Data Reduction System, as well as some of the tools under development by the MUSE consortium and the DAHLIA team to handle the large MUSE datacubes (about 4x?10^8 pixels) to recover the original astrophysical signal.
BlueMUSE is an integral field spectrograph in an early development stage for the ESO VLT. For our design of the data reduction software for this instrument, we are first reviewing capabilities and issues of the pipeline of the existing MUSE instrument. MUSE has been in operation at the VLT since 2014 and led to discoveries published in more than 600 refereed scientific papers. While BlueMUSE and MUSE have many common properties we briefly point out a few key differences between both instruments. We outline a first version of the flowchart for the science reduction, and discuss the necessary ch…
The Multi Unit Spectroscopic Explorer (MUSE) is an integral field spectrograph on the Very Large Telescope Unit Telescope 4, capable of laser guide star assisted and tomographic adaptive optics using the GALACSI module. Its observing capabilities include a wide field (1 square arcmin), ground layer AO mode (WFM-AO) and a narrow field (7.5"x7.5"), laser tomography AO mode (NFM-AO). The latter has had several upgrades in the 4 years since commissioning, including an optimisation of the control matrices for the AO system and a new sub-electron noise detector for its infra-red low order wavefront …
We present recent results obtained with the VLT/MUSE Integral Field Spectrograph fed by the 4LGSF and its laser tomography adaptive optics module GALACSI. While this so-called narrow-field mode of MUSE was not designed to perform directly imaging of exoplanets and outflows, we show that it can be a game changer to detect and characterize young exoplanets with a prominent emission lines (i.e Hα, tracer of accretion), at moderate contrasts. These performances are achieved thanks to the combo of a near-diffraction limited PSF and a medium resolution spectrograph and a cross-correlation approach i…
Context. Adaptive optics (AO) systems greatly increase the resolution of large telescopes, but produce complex point spread function (PSF) shapes, varying in time and across the field of view. This PSF must be accurately known since it provides crucial information about optical systems for design, characterisation, diagnostics and image post processing. Aims. We develop here a model of the AO long exposure PSF, adapted to various seeing conditions and any AO system. This model is made to match accurately both the core of the PSF and its turbulent halo. Methods. The PSF model we develop is base…
The Multi Unit Spectroscopic Explorer (MUSE) is a second-generation VLT panoramic integral-field spectrograph currently in manufacturing, assembly and integration phase. MUSE has a field of 1x1 arcmin2 sampled at 0.2x0.2 arcsec2 and is assisted by the VLT ground layer adaptive optics ESO facility using four laser guide stars. The instrument is a large assembly of 24 identical high performance integral field units, each one composed of an advanced image slicer, a spectrograph and a 4kx4k detector. In this paper we review the progress of the manufacturing and report the performance achieved with…
Characterization of the MUSE NFM PSF as a function of atmospheric conditions: TipTop calibration
European Southern Observatory (ESO)（欧洲南方天文台）；INAF – Osservatorio Astrofisico di Arcetri（意大利国家天体物理研究所阿切尔菲天文台）；Finnish Centre for Astronomy with ESO, (FINCA), University of Turku（图尔库大学芬兰ESO天文中心）；Tuorla Observatory, Department of Physics and Astronomy, University of Turku（图尔库大学图奥拉天文台）；Turku Collegium for Science, Medicine and Technology (TCSMT), University of Turku（图尔库大学图尔库科学技术学院）；DOTA, ONERA（法国航空航天发展局）
The first observations of laser guide star photons Raman-scattered by air molecules above the Very Large Telescope (VLT) were reported in June 2017. The initial detection came from the Multi-Unit Spectroscopic Explorer (MUSE) optical integral field spectrograph, following the installation of the 4 Laser Guide Star Facility (4LGSF) on the Unit Telescope 4 (UT4) of the VLT. In this Letter, we delve further into the symbiotic relationship between the 4LGSF laser guide star system, the UT4 telescope, and MUSE by monitoring the spectral contamination of MUSE observations by Raman photons over a 27 …
We present the PHANGS-MUSE survey, a programme using the MUSE IFS at the ESO VLT to map 19 massive $(9.4 < \log(M_{*}/M_\odot) < 11.0)$ nearby (D < 20 Mpc) star-forming disc galaxies. The survey consists of 168 MUSE pointings (1'x1' each), a total of nearly 15 Million spectra, covering ~1.5 Million independent spectra. PHANGS-MUSE provides the first IFS view of star formation across different local environments (including galaxy centres, bars, spiral arms) in external galaxies at a median resolution of 50~pc, better than the mean inter-cloud distance in the ionised interstellar medium. This `c…
AnisoCADO is a Python package for generating images of the point spread function (PSF) for the european extremely large telescope (ELT). The code allows the user to set many of the most important atmospheric and observational parameters that influence the shape and strehl ratio of the resulting PSF, including but not limited to: the atmospheric turbulence profile, the guide star position for a single conjugate adaptive optics (SCAO) solution, differential telescope pupil transmission, etc. Documentation can be found at https://anisocado.readthedocs.io/en/latest/
A ground-layer adaptive optics system (GLAO) uses a single adaptive mirror to partially correct the wavefront for atmospheric and telescope aberrations over a wide field of view. Instead of reaching diffraction limit on a narrow field, the idea is to provide partial improvement of the PSF over a wide field appropriate for multi-object spectrographs or wide field imagers. We derive an analytic formulation for the GLAO corrected PSF and then apply that in developing a methodology for calculating sensitivity improvement for astronomical instruments.
We present the results of an on-sky point spread function reconstruction (PSF-R) experiment for the Gemini North telescope adaptive optics system, Altair, in the simplest mode, bright on-axis natural guise star. We demonstrate that our PSF-R method does work for system performance diagnostic but suffers from hidden telescope and system aberrations that are not accounted for in the model, making the reconstruction unsuccessful for Altair, for now. We discuss the probable origin of the discrepancy. In the last section, we propose alternative PSF-R methods for future multiple natural and laser gu…
Modern Giant Segmented Mirror Telescopes (GSMT) like the Extremely Large Telescope (ELT), currently under construction depend heavily on Adaptive Optics (AO) systems to correct for atmospheric turbulence. To be able to correct wider fields of view (FoV), Multi-Conjugate Adaptive Optics (MCAO) systems were introduced, which use multiple guide stars to obtain an almost uniform correction over the FoV. However, a residual blur remains in the astronmical images due to the time delay stemming from the wavefront sensor (WFS) integration time and temporal response of the deformable mirror(s) (DM). Th…
Modeling the optical point spread function (PSF) is particularly challenging for adaptive optics (AO)-assisted observations owing to the its complex shape and spatial variations. We aim to (i) exhaustively demonstrate the accuracy of a recent analytical model from comparison with a large sample of imaged PSFs, (ii) assess the conditions for which the model is optimal, and (iii) unleash the strength of this framework to enable the joint estimation of atmospheric parameters, AO performance and static aberrations. We gathered 4812 on-sky PSFs obtained from seven AO systems and used the same fitti…
Astrometric precision and knowledge of the point spread function are key ingredients for a wide range of astrophysical studies including time-delay cosmography in which strongly lensed quasar systems are used to determine the Hubble constant and other cosmological parameters. Astrometric uncertainty on the positions of the multiply-imaged point sources contributes to the overall uncertainty in inferred distances and therefore the Hubble constant. Similarly, knowledge of the wings of the points spread function (PSF) is necessary to disentangle light from the background sources and the foregroun…
Taiyuan University of Technology（太原理工大学）；Durham University（杜伦大学）
Ground based optical telescopes are seriously affected by atmospheric turbulence induced aberrations. Understanding properties of these aberrations is important both for instruments design and image restoration methods development. Because the point spread function can reflect performance of the whole optic system, it is appropriate to use the point spread function to describe atmospheric turbulence induced aberrations. Assuming point spread functions induced by the atmospheric turbulence with the same profile belong to the same manifold space, we propose a non-parametric point spread function…
