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VLT Laser Guide Star Facility Recovery

VLT Laser Guide Star Facility Recovery. 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.

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VLT Laser Guide Star Facility Recovery

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  1. VLT Laser Guide Star Facility Recovery 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 • Recovery of what? Degraded Im. Quality formLT 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 DBO - ESO Status Overview – CfAO meeting 26 March 2007 Oberti - 28.Jan.2006

  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. Average LGS flux depends on the season LGS FLUX 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 2.006x106 phot/m2 on the ground (spec: 1x106phot/m2 at Nasmyth) • Would correspond to ~3.2x105 cts/subap/sec at the Sinfoni WFS • LGS mv= 8.8 with calibrated photometry. The corresponding WFS magnitude is higher! 11 inch Celestron, 0.66”/pxl, 14-bit CCD LGSM had a 2250m baseline (Residencia)

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

  6. LGS Pointing • 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

  7. LGS Focussing • 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 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

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