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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Dealing with turbulence in MCAO Roberto Ragazzoni, Yazan Almomany, Carmelo Arcidiacono, Renato Falomo, Jacopo Farinato, Marco Gullieuszik, Osservatorio Astronomico di Padova (Italy); Emiliano Diolaiti, Matteo Lombini, Osservatorio Astronomico di Bologna (Italy); Alessia Moretti, Osservatorio Astronomico di Padova (Italy); Giampaolo Piotto, Univ. degli Studi di Padova (Italy); Enrico Marchetti, Robert Donaldson, European Southern Observatory (Germany); Roberto Turolla, Univ. Degli Studi di Padova (Italy)

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology What is MCAO…??? Why is important the knowledge of the 3D turbulence???

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Telescope DM1 DM2 Turbulent layers #2 #1 Atmosfera WFS UP Multi Conjugated Adaptive Optics: MCAO

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology An historical perspective… MCAO is a vision of J. Beckers in 1988 Pyramid WFS envisaged in 1995 Layer Oriented approach is shown in Backaskog 1999 and Munich 2000 LO approved as part of MAD in 2001 MCAO with 3SH and LO are on the sky in 2007!

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Canary, fall 2001

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Why pyramid..? They take advantage of the full aperture (spot is diffraction limited on the pin of the pyramid) Better limiting magnitude Better aliasing (larger Strehl in HO mode) It is a pupil plane WFSensor! It is cheap in terms of pixels usage

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Prototyping (4 stars) Optical design Optomechanical design Glass and Alluminum

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Laboratory test in closed loop give evidence of higher limiting magnitude for the Layer Oriented WFS w.r.t the Star Oriented ~1.5 magnitude fainter LOWFS SHWFS vWFS on MAD vs 3SH … : FoV of single stars enlarger ~0.95arcsec!

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology The MAD-LO run Basically the whole group of LO-MAD plus ESO support (3 initially, then 1) Total of 9 contiguous nights First 3 night of technical run under ESO responsibility Then 6 nights of GTO basically devoted to science

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology 70.5

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology 107x107arcsec GLAO 5 NGSs Vmag tot=13.8 Here is S=10% Var. +/- 3%

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Not a star!!!

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology A. Moretti et al.

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology We think to have material for further 3 science papers on other objects… A very productive run indeed, but…. Which is the achieved quality compared to the SO one? Which is the sky coverage one can compute given the actual performances? Any answer will be plagues by doubts about seeing, f_G, scaling laws…

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology A. Moretti et al. Omega Cen (public data) NGC6388 (LO data)

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology LayerOriented Star Oriented Layer oriented Star Oriented With an uniform standard reduction magnitude errors are slightly (10%) better for LO than SO, and viceversa for centroiding

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology 3x V=11.5

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology 3x V=12 3x V=13

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology 3x V=12 3x V=13 ~1.5mag

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Red: estimates given in the 2002 paper Blue: left – actual measurements in the sky; right – laboratory measures

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Red: estimates given in the 2002 paper Blue: left – actual measurements in the sky; right – laboratory measures

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Remember that the CCD is blue-sensitive…!!! 0.70 … … … 0.25 !

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Areas to make MCAO with NGSs more sensitive… Using the Taylor hypothesys Layer Oriented sees the layers of turbulence so can use several previous measurements to estimate the coming one (not prediction, but better SNR of WFS… Frozen layer 2000

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Areas to make MCAO with NGSs more sensitive… Using non linear co-addition of stars It is well known that enlarging the FoV do not improve the correction because it is lowered the thickness of turbulence sampled… if linearly coadded!!! a 2001

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Linear or non-linear…??? Layer you are looking (say 8km) a few stars

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Linear or non-linear…??? Layer you are looking (say 8km) a lot of stars

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Linear or non-linear…??? Layer you are looking (say 8km) a few stars This layer is sampled Ok…

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Linear or non-linear…??? Layer you are looking (say 8km) a lot of stars This layer is smoothed out!!

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Linear or non-linear…??? Layer you are looking (say 8km) a lot of stars + ++ Numerically averaging leads to the same trouble!

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Linear or non-linear…??? Layer you are looking (say 8km) a lot of stars multiply or adding the square It only goes to zero if all the WF is flatted…

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Linear or non-linear…??? Layer you are looking (say 8km) a lot of stars multiply or adding the square It only goes to zero if all the WF is flatted…

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Linear or non-linear…??? Layer you are looking (say 8km) a lot of stars multiply or adding the square It only goes to zero if all the WF is flatted…

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Linear or non-linear…??? Layer you are looking (say 8km) a lot of stars multiply or adding the square It only goes to zero if all the WF is flatted…

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Propagation noise is more complex… 1 st DM 2 nd DM Pupil plane

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Non-linear behaviour… Algorithm is not conventional as the sign of correction is unknown A toy-model using the bang-bang algorithm gives a bandwidth that is at worst 2x less… There is a geometrical limit, that is about 10 for a 42m telescope (and 25 for a 100m one…) This makes the gain in FoV of 25 So the overall gain is in the ballpark of 12..!!!! One order of magnitude improvement in sky coverage!!!

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Future of Layer Oriented A LO instrument started in 2002 now would produce big science NIRVANA is not optimized for deep single arm MCAO but, ok… In the timescale of a new instrument LGSs should prove their maturity (or not???) Unexplored ways to improve sensitivity include Taylor hypothesis usage and non-linear coaddition of reference stars Mixing up LGS and NGS is a safe, robust way, and there are unexplored new schemes for that

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Metapupil 4 NGSs … and 2 LGSs! Pupil plane Focal plane NGS LGS

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Dealing with turbulence in MCAO Roberto Ragazzoni INAF – Padova (Italy) Alghero, Sept. 17 th 2008 Astronomy meets Metereology Conclusions… Beating 3D turbulence, after 20yrs from the JDB is a reality… MCAO is in its infancy… There are unexplored realms where NGSs based MCAO can achieve larger sky coverage… LGS are being deployed on a few sites and will progress as well… Stay tuned for a turbulent future!!!

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