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An Introduction to Closure Phases
John Monnier (Smithsonian Astrophysical Observatory)
Abstract:
The fluctuating path delays caused by atmospheric turbulence generally
scramble the fringe phases measured by an optical interferometer. Left
uncorrected, this loss of phase information would make imaging of complex
sources impossible. In this lecture, I will introduce general properties
of Closure Phases and how this powerful concept can be used to recover
much of the "lost" phase information. Simple closure phase examples for
prototypical sources will be given before discussing how to incorporate
this information in image reconstruction using "self-calibration"
techniques.
Viewgraphs PowerPoint 4176k Bytes.
A note on the use of Summer School material.
Suggested Reading:
- An Introduction to Closure Phases
J.D. Monnier, Chapter 13 in
Principles of Long Baseline Stellar Interferometry (JPL, 1999).
- Radiointerferometric imaging of weak objects in conditions of poor phase stability: the relationship between speckle masking and phase closure methods
T.J. Cornwell
Astron. Astrophys. 180, 269-274 (1987).
- Synthetic aperture imaging at infrared wavelengths
Haniff et al.
Mon. Not. R. Astron. Soc. 241, 51P-56P (1989).
- A phase sensitive interferometer technique for the measurement of the Fourier transforms of spatial brightness distributions of small angular extent
R.C. Jennison
Mon. Not. R. Astron. Soc. 118, 276-284 (1958).
- The mapping of compact radio sources from VLBI data
A.C.S. Readhead and P.N. Wilkinson
Astrophys. J.223, 25-36 (1978).
- Diffraction-limited imaging with ground-based optical telescopes
A.C.S. Readhead et al.
Astron. J.95, 1278-1296 (1988).
- Maximum entropy image reconstruction: General algorithm
J. Skilling and R.K. Bryan
Mon. Not. R. Astron. Soc. 211, 111-124 (1984).
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Course Notes from the 2002 Michelson Interferometry Summer School
Smithsonian Astrophysical Observatory, Cambridge Massachusetts, June 24-28, 2002
Edited by P.R. Lawson (JPL), MS 301-451 Jet Propulsion Laboratory
Pasadena, California, 91109
Last Updated 9 February 2004
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