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THE EFFECT OF THE LOCAL ATMOSPHERIC
ENVIRONMENT ON ASTRONOMICAL OBSERVATIONS

by LORENZO ZAGO

Revised edition - Copyright © 2010 by Lorenzo Zago.
Saving and printing of individual pages is permitted for research purpose only.
Copies of the integral report are also available from the author at a nominal price of 100 US $ plus mailing.

Lorenzo Zago,  email, last updated August 3rd, 2010 

• Abstract
• Acknowledgements
• List of main symbols
• Introduction
  • General presentation
  • Scope and summary
  • Original contributions
  • The ESO Very Large Telescope
• The image quality of a telescope
  • Seeing
  • Thermal turbulence, light propagation and image size
    • The microstructure of the temperature field in the atmosphere
    • The microstructure of the index of refraction and its relationship with "seeing"
  • Effects of wind loads
    • Wind turbulence
    • Guiding errors
    • Wind buffeting on "thin" primary mirrors
  • The overall image quality and its budget
• Telescope enclosures
  • The requirements of telescope enclosures
  • The recent evolution of design concepts for telescope enclosures
    • Classical domes
    • The MMT and its rotating building
    • Improvements in conventional domes
    • The ESO New Technology Telescope
    • Average seeing at different telescopes at La Silla
    • The ESO Very Large Telescope
    • A summary of outstanding problems
• Telescope aerodynamics
  • Wind loading on telescopes
    • Classical domes
      • Measuring equipment and procedure
      • Results
    • NTT rotating building
    • Cylindrical enclosure (VLT)
    • Retractable enclosure
    • Synthesis
  • Wind loading on the primary mirror
    • Outline of the problem
    • Wind tunnel tests with the telescope exposed
    • Tests with the 3.5-m mirror dummy
      • Measurements
      • Main results
      • Relationship between pressure fluctuations and wavefront aberrations
    • Wind tunnel measurements of the pressure/velocity field on the mirror
      • Measurements
      • Pressure-speed correlation
      • Correction of wind deformations by active optics systems
    • Synthesis
• Local "seeing"
  • The relationship of the temperature structure parameter to the mean velocity and temperature fields
  • Dome seeing
    • Literature review
    • Causes of dome seeing
    • The "steady local air" dome effect
    • Scaling variables and similarity of dome seeing
    • An order-of-magnitude estimate of dome seeing
    • Mirror seeing
    • Analysis of telescope image quality data data
      • Data bases
      • Analysis procedure
      • HRCam data
      • FOCam data
      • Analysis summary
    • Seeing caused by heat generation at the secondary mirror unit
    • Seeing and natural ventilation
    • Synthesis
  • Mirror seeing
    • Physical description of mirror seeing
    • Free convection
    • Mixed and forced convection
    • The cold mirror case
    • Experimental studies
      • A mirror seeing experiment with a 4-cm mirror
      • Seeing tests on a 62-cm mirror
      • Seeing tests on a 254-mm mirror
      • Other laboratory measurements
    • Analysis and modeling
      • Mirror in free convection
      • Ventilated mirror
      • Active correction of mirror seeing
    • Synthesis
  • Numerical models
    • Seeing computation by means of a fluid flow numerical model
    • CFD for evaluating mirror seeing
    • Application to a 1.25-m telescope project
    • Synthesis
  • Surface layer seeing
    • The optimum height of a telescope base
    • Reduced scale simulation of near-ground seeing
    • Similarity rules for near-ground flow
    • Pilot test for direct measurement of seeing
• Systems Engineering
  • Engineering criteria and guidelines
  • Wind turbulence on the telescope
  • Wind buffeting on the primary mirror
  • Dome seeing
  • Mirror seeing
  • Random conditions and operational aspects
  • A statistical model of telescope image quality
    • Parameterization of seeing and guiding effects
    • Wind versus seeing for the primary mirror
    • Guiding errors
    • Computation of the CIR figure
    • Computation procedure
    • Results and discussion
    • Synthesis
• Conclusions
• References
• The enclosure of the VLT 8-m telescopes
• Aerodynamic measurements on mirrors
  • Measurements with the 3.5-m mirror dummy
  • Measurements in the NTT
  • Measurements in the inflatable dome
  • Wind tunnel measurements
    • Velocity measurements above the mirror
    • Differential pressure measurements across the mirror

   
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