First statistics of the isopistonic angle for long baseline interferometry

Abstract

To reach a suitable limiting magnitude with a multi-aperture interferometer, we need to cophase the different telescopes using a reference source. The latter should be located in the same isopistonic domain as the science source. We developed a direct analytical expression of deducing the isopistonic angle from atmospheric optical parameters as seeing, isoplanatic angle and outer scale. All of these atmospheric turbulence parameters are measured by the Generalized Seeing Monitor (GSM). The first statistics of the isopistonic angle obtained from the GSM data are presented and comparison between the major sites over the world are discussed (

Potential and sky coverage for off-axis fringe tracking in optical long baseline interferometry

“…Our analysis of the anisopistonic error is based on atmospheric models and on two campaigns of outer scale measurements at Paranal described in Ziad et al (2016). Although these atmospheric models are relatively well supported by experimental evidence of AO systems, the specific anisopistonic error has not been measured extensively.…”

“…We first investigated the issue in the context of optical interferometry in Antarctica (Elhalkouj et al 2006), which triggered the parametric analysis of the anisopistonic error that we use here (Elhalkouj et al 2008). Our isopistonic angle estimates are based on on-site testing campaigns with the Generalized Seeing Monitor (GSM) including two campaigns at Paranal (1998 and and one campaign at Dome C. We have combined our analytic computation of the anisopistonic error with the statistics obtained on all these sites on the Fried parameter, the coherence time, the isoplanatic angle, and the outer scale, to produce the set of isopistonic angle statistics of Ziad et al (2016) that is used in the present paper.…”