Simulating a dual beam combiner at SUSI for narrow-angle astrometry

TL;DR

This paper presents a simulation framework to evaluate the performance and astrometric precision of SUSI's dual beam combiners, PAVO and MUSCA, for narrow-angle astrometry of binary stars.

Contribution

It introduces a new simulation tool for assessing the combined performance of PAVO and MUSCA at SUSI and future sites.

Findings

Simulation results show expected astrometric precision for the dual beam setup.

Performance evaluation of PAVO and MUSCA for binary star measurements.

Guidelines for future site performance based on simulations.

Abstract

The Sydney University Stellar Interferometer (SUSI) has two beam combiners, i.e. the Precision Astronomical Visible Observations (PAVO) and the Microarcsecond University of Sydney Companion Astrometry (MUSCA). The primary beam combiner, PAVO, can be operated independently and is typically used to measure properties of binary stars of less than 50 milliarc- sec (mas) separation and the angular diameters of single stars. On the other hand, MUSCA was recently installed and must be used in tandem with the for- mer. It is dedicated for microarcsecond precision narrow-angle astrometry of close binary stars. The performance evaluation and development of the data reduction pipeline for the new setup was assisted by an in-house computer simulation tool developed for this and related purposes. This paper describes the framework of the simulation tool, simulations carried out to evaluate the performance of each beam combiner and the expected astrometric precision of the dual beam combiner setup, both at SUSI and possible future sites.