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Astron. Astrophys. 353, L29-L32 (2000)

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Letter to the Editor

Differential piston angular anisoplanatism for astronomical optical interferometers

Simone Esposito, Armando Riccardi and Bruno Femenía

Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy

Received 9 August 1999 / Accepted 6 December 1999


This letter considers the problem of measuring the differential piston of a two-pupil astronomical optical interferometer which uses a reference source located at a different position with respect to the observed scientific target. The differential piston error as a function of the angular distance between the reference and astronomical target can be calculated using existing formulae for Zernike polynomial correlation coefficients. This allows the definition of an isopistonic angle that resembles the isoplanatic angle for Adaptive Optics System wavefront correction. Values obtained for the isopistonic angle are comparable to the isoplanatic angle showing that sky-coverage could be a potential problem for an astronomical interferometer aiming to correct for atmospheric fringe jitter.

Key words: instrumentation: interferometers – atmospheric effects

Send offprint requests to: S. Esposito

Correspondence to: S. Esposito

© European Southern Observatory (ESO) 2000

Online publication: January 18, 2000