OPTICON JRA4 Coordinator Dr Alain ChelliLaboratoire d’Astrophysique de Grenoble & Jean-Marie Mariotti Center, Universite Joseph Fourier,BP53, Grenoble Cedex 9, FranceTelephone: +33 (0)4 76 63 58 37E-mail: chelli@obs.ujf-grenoble.fr

Work Package Leaders

WP1.1: Dr Uwe Graser (MPIA) Dr Denis Mourard (OCA)WP1.2: Dr Mario Gai (Torino)WP2: Dr Gilles Duvert (PI/LAOG) Dr Gerard Zins (PM/LAOG)

Contacts

OPTICON - The Optical Infrared Coordination Network for Astronomy

JRA4 - Interferometry

OPTICON is funded by the European Commission under Contract RII3-CT-2004-001566

Interferometry – the combination of multiple telescopes in a single coherent array – is a powerful technique that allows astronomers to obtain unprecedented angular resolution (milliarcseconds), and to measure motion of celestial bodies with extreme precision (microarcseconds).

Context: The European Southern Observatory’s (ESO) Very Large Telescope Interferometer (VLTI) is the most ambitious ground based interferometry project underway, with four 8m telescopes and up to four 1.8m auxiliary telescopes. The Large Binocular Telescope (LBT) will combine two 8.2m mirrors. The Ohana project will extend interferometry to baselines of several hundred metres. The European Space Agency’s (ESA) Darwin mission will aim at detecting and characterising habitable exo-planets.

Objectives: The goal of JRA4 is to contribute to the integration of optical interferometry into mainstream astronomy. The participants of JRA4 will take actions to ensure that Europe will play a leading role in the development of optical interferometry over the next decade and to enable European astronomers to fully exploit the scientific potential of existing and planned facilities.

Description of JRA4

The near-term scientific productivity of interferometers is limited mainly by: (1) the inherent limitations of the existing focal plane instrumentation and the difficulties of phasing and cophasing the elements of interferometric arrays, (2) the lack of software tools for the analysis and interpretation of the data.

JRA4 has several work packages to address these issues:

WP1.1 (Advanced instruments)Support up to 7 concept studies for the second generation of VLTI instruments, paying special attention to multi-beam combiners (4 to 8 beams). The most promising concepts will be selected for more detailed feasibility studies.

WP1.2 (Cophasing and Fringe Tracking)Focus on analysis techniques and optimisation in three areas:- current cophasing performances- measurement operations- cophasing schemes for future instruments

WP2 (Off-line data interpretation soft)develop a dedicated software package

Participants

• France: INSU/JMMC (CRAL, LAOG, OCA, ONERA, UNSA) • Germany: FRINGE (MPIA, MPIfR)• Netherlands: NOVA/NEVEC• United Kingdom: Cavendish Laboratory• Italy: Osservatorio di Torino• Belgium: University of Liège• Switzerland: Observatoire de Genève• Portugal: CAUP • Austria: University of Vienna• Israel: Technion• Poland: Nicolaus Copernicus University• Hungary: Konkoly Observatory• Czech Republic: Academy of Science• Spain: Instituto Astrofisica Andalucia• ESA, ESO

for the analysis and interpretation ofdata from optical/infrared interferometry. This software will provide:

- tools for fitting geometrical models to sparse sets of calibrated data (visibility, differential and closure phase), - facilities for astrometric data reduction (stellar proper motions and parallax) and to fit orbits of multiple stars and planetary companions.- tools for image reconstruction