1. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ Instrumentation Concepts Ground-based Optical Telescopes Keith Taylor (IAG/USP) Aug-Nov, 2008 Aug-Sep, 2008 IAG-USP (Keith Taylor)

2. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ Ground Layer Adaptive Optics (GLAO) Thanks to: Andrei Tokovinin (SOAR) Norbert Hubin (ESO)

3. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ WHAT IS GROUND LAYER AO? WFSs Reference Stars Telescope High Altitude Layer Ground Layer DM conjugated Telescope pupil Real Time Computer Averaged WF.. Ground Layer Altitude Layers Laser beams

4. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ Ex: 50% of the time there is 55% OR LESS turbulence in the 1 st 500m More measurements are being carried out (M. Sarazin) Does a ground layer exist? PARANAL OBSERVATORY Courtesy: M. Sarazin

5. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ Seeing-limited (>90% of Ground-based Astronomy!) Ground Layer Adaptive Optics Better seeing in wider field Turbulence profile Guide star(s) Gain? Diffraction limit (full AO or MCAO) =

6. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ « Ground Layer » Adaptive Optics [GLAO] GLAO:  multi-GS WFS  single ground DM correcting average perturbation ~ near ground turbulence No Correction: Seeing limit single Ground DM GLAO: reduced apparent seeing seeing improved and stabilized in very large FoV gain ~2 in 10 arcmin for NIR VLT obs. Expected performance:FoV

7. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ Turbulence Profile and ground layer Mauna Kea, October 22/23, 2002: G-scidar 0km 5km 10km 15km Data: J.Vernin, A.Ziad

8. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ Turbulence Profile and ground layer CERRO TOLOLO OBSERVATORY Courtesy: M. Sarazin R. Wilson

9. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ Turbulence Profile and ground layer CERRO TOLOLO OBSERVATORY Courtesy: M. Sarazin

10. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ Investigation of Ground layer at Paranal Multi Aperture Scintillation Sensor MASS + DIMM: Cn 2 profile SLODAR: Slope Detection and ranging: Higher resolution of ground layer Courtesy: R. Wilson

11. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ GLAO as seeing reducer? Improved seeing, Sr(K) ~ 4% 8’ FOV SeeingPSF on-axisPSF off-axis Seeing reducer Reduced exposure & Telescope time Better light concentration Reduced confusion in Stellar populations & Cluster fields

12. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ Science with GLAO Dynamics of galaxies, AGNs (+IFU) Stellar populations, clusters (confusion!) Supernovae, cepheids Weak lensing ISM (PNe, jets) and more… GLAO benefits most “classical” astronomical programs

13. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ GLAO as seeing reducer? K Band, gain: 100% FWHM Y Band, Gain: 30% Seeing With AO

14. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ GLAO improves Ensquared Energy? Y Band, gain: 50% K Band, EE doubled With AO Seeing Pixel: 0.1”

15. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ GLAO reduces confusion? K Band, gain: 40% Y Band, Gain: 30% Seeing With AO Yes but more difficult!

16. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ GLAO and full sky coverage? Need Laser artificial stars for WFS tomography because of: Median to bad seeing conditions assumptions Science performed down to short λ Require Natural Guide Star for Tip-tilt correction Tip-tilt limiting magnitude (R-Band) Probability for (top to bottom) 1,2,3 TT NGS In 1arcmin annular FOV 1 VIS NGS

17. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ GLAO Gain MCAO GLAO Resolution (K-band) 0.05”0.2” Field diameter 1’ 10’ Number of pixels 1.4 Mpix9 Mpix + in the visible!!! Sky coverage ~100%

18. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ GLAO in the visible? @750nm; FOV=1’ GLAO Seeing

19. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ Two GLAO systems S-GLAO 5 sodium LGSs R-GLAO Rayleigh LGS

20. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ MASS/DIMM measures

21. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ Compare S-GLAO with R-GLAO S-GLAO R-GLAO 17% at 8km, 83% at 0.5km

22. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ Further comparison

23. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ Typical night: Jan 11/12, 2003 Seeing ~0.5  m ~0.7  m

24. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ Typical night: Jan 15/16, 2003 Seeing ~0.5  m ~0.7  m

25. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ Statistics: FWHM 25%50%75% Seeing (arcsec) 0.941.111.33 0.5  m 0.380.530.71 0.7  m 0.220.310.49 1.0  m 0.170.220.30

26. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ SAM = SOAR Adaptive Module Rayleigh LGS 355 nm, 8W, 10km S-H WFS, 9x9 Bimorph DM CCD imager FoV = 3’x3’ Visitor instrument Collimated space PDR: 2004 First light: 2006 (now 9/09) LGS: 2007 (now 9/10)

27. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ Optical design: OAP All-reflective Excellent quality Collimated space

28. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ SAM as adaptor

29. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ GLAO: useful for most astronomical programs Ground Layer Adaptive Optics = Seeing reducer Reduced Seeing => reduced exposure & telescope times Reduced seeing => Reduced confusion in Stellar populations & Cluster fields Ground Layer Adaptive Optics = Seeing “stabilizer” Seeing stabilizer => better percentile seeing for your site! Seeing reducer is “easily” achievable at all λs (down to vis.) High Sky coverage GLAO systems will benefit most astronomical programs Seeing reducer = light concentration: Sufficient for distant (“small”) galaxies with low surface brightness (0.2-0.1” pixel enough)

30. Aug-Nov, 2008 IAG/USP (Keith Taylor) ‏ Conclusions GLAO is complementary to AO, MCAO Opens “visible” window, all-sky Rayleigh LGS is quite good SAM _ first implementation, test-bench Need data on turbulence in the first km!