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Astron. Astrophys. Suppl. Ser.
Volume 121, Number 3, March 1997
Page(s) 553 - 568
DOI: 10.1051/aas:1997323

A&A Supplement series, Vol 121, March 1997, 553-568

Received November 13, 1995; accepted November 7, 1996

Correction of the ``piston effect'' in optical astronomical interferometry

I. Modulus and phase gradient of the visibility function restoration

G. Perrin tex2html_wrap505

Send offprint request: G. Perrin (
Observatoire de Paris, DESPA, 5 place Jules Janssen, F-92195 Meudon, France


An a posteriori method to cancel out atmospheric optical path fluctuations to achieve accurate phase restoration and spectral analysis of interferograms is presented in this paper. The correction algorithm is based on classical noise reduction methods. The consequence of piston noise is twofold: 1) loss of spectral information; 2) loss of visibility phase. A method to measure the modulus and the phase gradient of visibilities is explained and examples of restoration of simulated spectra and visibilities for various S/N ratios are presented.

keywords: atmospheric effects -- methods: data analysis -- technics: interferometric

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