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Report of the Working Group Calibration, Monitoring and Site

Report of the Working Group Calibration, Monitoring and Site. Conveners: M. Teshima, B. Khélifi Members: J. Cortina, R.G. Lopez, M. Gaug, E. Giraud, R. Mirzoyan, P. Mayumdar, M. Mori, V. Mitev, M. Panter, A. Sillampaä, S. Swordy, J.-P. Tavernet, G. Vasileiadis, S. Wagner

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Report of the Working Group Calibration, Monitoring and Site

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  1. Report of the Working GroupCalibration, Monitoring and Site Conveners:M. Teshima, B. Khélifi Members:J. Cortina, R.G. Lopez, M. Gaug, E. Giraud, R. Mirzoyan, P. Mayumdar, M. Mori, V. Mitev, M. Panter, A. Sillampaä, S. Swordy, J.-P. Tavernet, G. Vasileiadis, S. Wagner Activity:5 phone-conferences, email exchanges  Draft for the Letter of Intend

  2. Calibration and atmospheric monitoring

  3. What to calibrate and to monitor? • Atmospheric monitoring: Extinction coefficient • Optical components: Mirrors, funnels, photocathods • Camera electronics: Gain, flat fielding, usable pixels, …  Conversion factor: # ADC per Cherenkov photons B. Khélifi WG Calibration/Monitoring/Site Paris, 02/03/2007

  4. Camera performances • Functioning parameters of the cameras not treated here, Just the camera characteristics used for the data analysis • Channel noise • From electronics • From Night Sky Background  No need of specific instrumentation • Conversion factor: #ADC per photoelectron • Components: efficiency of the integration window, electronic gains, Photodetector internal gain  LED flashers B. Khélifi WG Calibration/Monitoring/Site Paris, 02/03/2007

  5. Camera performances (2) • Flat fielding • Different detection efficiency between channels Funnels, photocathods • LED flashers • Usable channels • Malfunctioning reasons depend on camera technology • Big efforts should be done to their identifications  No need of specific instrumentation B. Khélifi WG Calibration/Monitoring/Site Paris, 02/03/2007

  6. Optical components • Involved components: Mean Photocathod efficiency, mean funnel and mirrors efficiency • This global efficiency allows an absolute calibration  Use of muon rings B. Khélifi WG Calibration/Monitoring/Site Paris, 02/03/2007

  7. Atmospheric monitoring • Standard weather conditions Meteo station • Water vapor and cloud monitoring Infrared radiometers B. Khélifi WG Calibration/Monitoring/Site Paris, 02/03/2007

  8. Atmospheric monitoring (2) Results of LIDAR simulations V. Mitev LIDAR TRmodel = 0.9498 TRmeas = 0.9508 (9-10.4 km) Cirrus cloud TRmodel = 0.5836 TRmeas = 0.5830 (3-5 km) Troposphere/Desert Dust 60° Dust layer • Estimation of the optical depth above telescopes: • Photometric telescope • Continuous monitoring • Cross-check with LIDAR • Atmosphere profile • Radiosondes: seasonal variations Transmissometer (transmissivity at the ground layers) B. Khélifi WG Calibration/Monitoring/Site Paris, 02/03/2007

  9. Conclusions • Draft of the WG has been submitted (8 pages) • For the Design Study (Working Package 12): • Big efforts on the LIDAR technique to routinely correct for atmosphere variations  Closer work with atmospheric physicists • Efforts to measure and to use the seasonal atmospheric profile measured by radiosondes • Apply and test these atmospheric corrections to the data analysis B. Khélifi WG Calibration/Monitoring/Site Paris, 02/03/2007

  10. Candidates for CTA sites

  11. Criteria of selection • Altitude above 1.5 km • Small cloud coverage: good nights > 60% • Atmosphere transparent and dry • Latitude around +30° N and -30° S • Facility of site access • Political stability • … B. Khélifi WG Calibration/Monitoring/Site Paris, 02/03/2007

  12. CTA North B. Khélifi WG Calibration/Monitoring/Site Paris, 02/03/2007

  13. CTA South B. Khélifi WG Calibration/Monitoring/Site Paris, 02/03/2007

  14. Known Cherenkov sites MACE CANGAROO III • Thomas Highlands, Namibia • Tenerife Teide, La Palma • Himalaya Hanle (India) • Woomera (Australia) • Good quality possible sites • Useful for comparisons B. Khélifi WG Calibration/Monitoring/Site Paris, 02/03/2007

  15. Sites for optical astronomy La Silla Paranal • Chilean sites • La Silla - Atacama desert • Paranal – 12 km from coast (VLT) • La Montura • … • High quality atmospheric conditions • Between 2.000 and 3.000 m a.s.l. • Caution: available area B. Khélifi WG Calibration/Monitoring/Site Paris, 02/03/2007

  16. Exploration of new sites Chajnantor Archibarca Catamarca Erasmus • Based on satellite survey Eramus  Staden, 2001 • Cloud cover, water vapor • Data over 5 years • 5-10 candidates in Northern Argentina • Good fraction of clear nights • Altitude above 3.500 m a.s.l. • Very large area • Can be isolated clear nights 1st half B. Khélifi WG Calibration/Monitoring/Site Paris, 02/03/2007

  17. Exploration of new sites (2) S 24° 32.118’ W 67° 4.363’ 3722 m a.s.l. POCITOS N Chajnantor Sus7052 • On site measurements • Telescope: Newton with CCD cam. • U, V, B Antonio Pocitos Tolar G. Archibarca Pocitos ALMA 74% Catamarca 67% Plateau below ALMA site 60% La Silla Tolar Grande Erasmus • On site explorations (12-2006) • E. Giraud, G. Vasileiadis, M. Gaczarzyk, T. Schweizer, A. Rovero, E. Colombo • 4 sites visited clear nights 1st half B. Khélifi WG Calibration/Monitoring/Site Paris, 02/03/2007

  18. Conclusions • Big activity of the WG members to identify candidates literacy, reports on web, personal contacts, visits, measurements,… • Draft of the WG has been submitted (23 pages) • Good starting point for the Design Study Even if Northern sites are so few and other possibilities have not yet investigated (e.g. South Utah) • For the Design Study (Working Package 4): • Use long-term data from satellites and in-situ measurements • Identify site facilities (for the access and the building phase) B. Khélifi WG Calibration/Monitoring/Site Paris, 02/03/2007

  19. Thank you to all for your contributions

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