1. VLT Laser Guide Star Facility Recovery DBO - ESO Status Overview – CfAO meeting 26 March 2007 ESO: E. Allaert, C. Araujo, G.Avila, D.Bonaccini Calia, E.Brunetto, B. Buzzoni, M. Comin, M. Cullum, C.Dichirico, M. Dimmler, I.Guidolin, W. Hackenberg, F.Koch, D. Popovic, M. Quattri, J. Quentin and A.Silber MPE/MPIA: Davies, S. Hippler, S, Kellner, U. Neumann, T. Ott, S. Rabien Oberti - 28.Jan.2006 Recovery of what? Degraded Im. Quality form LT Mech problems Recovery Action? Redesign and Construction LT M1 supports Extra Resources: 1.2 FTE + 120 kEUR Project Delay:11 months Results: Problem solved, very close to specs LGSF Status: Completed Commissioning – Science Phase

2. LGSF Launch Telescope

3. Commissioning runs 3 runs from October to December Dec and January together with NACO and SINFONI LGS-AO Doing science, Feb-March-April-May Issues: Pointing of LGS Focussing to the optimal height LGS fwhm LGS flux Operation with UT4 and AO systems Diagnostics

4. LGS observed with a side telescope (LGS Monitoring Telescope) Photometry done using several standards, V-band Johnson filter Done in two different nights in May 06, it gives similar LGS flux results:  LGS flux 2.006x10 6 phot/m 2 on the ground (spec: 1x1 0 6 phot/m 2 at Nasmyth )  Would correspond to ~3.2x 1 0 5 cts/subap/sec at the Sinfoni WFS  LGS m v = 8.8 with calibrated photometry. The corresponding WFS magnitude is higher! LGS FLUX 11 inch Celestron, 0.66”/pxl, 14-bit CCD LGSM had a 2250m baseline (Residencia) Average LGS flux depends on the season

5. Lgs fwhm depends on the uplink wavefront quality, but also on Sodium layer density distribution and on the lower atmospheric turbulence levels LGS FWHM

6. Mostly UT4-M2 flexures with gravity induces LT pointing deviations The effect is corrected by moving the fibre on the focal plane of the LT To bring the LGS at centerfield we will use the same method as for NGS (tool in prep.) LGS Pointing LGS

7. Repeatable focusing depends on temperature and sodium layer median altitude We have to collect more data during operation for a repeatable calibration. A tool for automatic focusing is in preparation, useful to speed up LGS acquisition LGS Focussing Current calibration is not satisfactory

8. Conclusions The LGSF can be used for LGS-AO observations Technical time with AO continues, to fine tune operations/performances Observing overhead will be reduced with tools to center/focus LGS during acquisition The LGS fwhm in our analytical predictions was smaller. We believe it is physical, it is important also for future projects with LGS systems. In the coming months LGS data will continue to be accumulated and analyzed It has not been a walk, but the team has cumulated very precious experience for the next complex systems