Astron. Astrophys. Suppl. Ser. 138, 355-363

Astrometric optical interferometry with non-evacuated delay lines

G. Daigne¹ and J.-F. Lestrade²

Send offprint request: G. Daigne

1 - Observatoire de Bordeaux, BP. 89, F-33270 Floirac, France
e-mail: daigne@observ.u-bordeaux.fr
2 - Dept. Arpèges, Observatoire de Paris-Meudon, F-92191 Meudon Cedex, France
e-mail: lestrade@obspm.fr

Received April 9; accepted June 8, 1999

Abstract:

The effects of longitudinal dispersion in long baseline optical interferometry with non-evacuated delay lines are analyzed. A new technique is proposed for group delay tracking, with phase measurements in two wavebands only. Sensitivity and instrumental uncertainties are further investigated, together with the dependence on stellar color temperature. To a precision level of a few 10^-10 rad, limiting factors in dual-field astrometry should be put under control with not too long interferometer baseline.

Key words: athmospheric effects -- techniques: interferometric -- astromety