2nd Generation Instrumentation for the Very Large Telescope Interferometer

PTDC/CTE-AST/098034/2008

Principal investigator
Paulo J. V. Garcia (Laboratório de Sistemas, Instrumentação e Modelação em Ciências e Tecnologias da Terra e do Espaço, Portugal)

Researcher in charge at CAUP
Mercedes E. Filho

Interferometry is a key astronomical technique at the core of existing infrastructures - the Very Large Telescope Interferometer (VLTI), of global infrastructures under construction - the Atacama Large Millimeter Array (ALMA), of global infrastructures selected by the European Strategy Forum on Research Infrastructures (ESFRI) and currently under study - the Square Kilometer Array (SKA).

Optical interferometry opens the unique parameter space of 1 milliarcsecond imaging and 10 micro-arcsecond astrometry in the near-infrared. Imaging the terrestrial planet forming regions of young stellar disks, the engines of nearby active galactic nuclei, searching for planets in nearby stars or probing the intense gravitational field in the Milky-way's super-massive black-hole are outstanding observations critical to answer front line open questions in modern astronomy or discovering new physics.

By continuing an effort that can be traced back to the Portuguese entrance in ESO in 2001, this project funds the Portuguese participation in the second generation instrumentation for the VLTI. The instruments are the GRAVITY astrometric experiment and the VSI spectroimager. These are the only approved ESO instrumentation with a Portuguese participation. Furthermore they are the only ESO VLT instrumentation under development referred in the ASTRONET Infrastructure Roadmap and with Portuguese participation.

A previous project was funded via the 2006 FCT call allowing the team:
a) to participate in the Phase A studies of VSI;
b) to take into account the beam properties of the VLTI and prepare the studies of the beam injection and acquisition cameras of VSI and GRAVITY;
c) to develop critical expertise of phase referenced imaging for VSI and GRAVITY.

The international recognition of the team in the field of optical interferometry is backed up by being the sole national participants in the OPTICON project in FP6 and FP7. In FP7 our participation was enlarged to the coordination of the optical interferometry networking work package of OPTICON. Furthermore, for the VSI instrument, the Portuguese partner chairs the instrument science team, a unique case in ESO instrumentation. In FP6 we coordinated the European project on training in
optical interferometry for the VLTI.

Our instrumental contribution builds on the tradition of near-infrared imaging expertise for high angular resolution acquired with the CAMCAO project. It consists in instrumental sub-systems integrated in the actual instrument maximizing the team participation in all critical review steps of the instruments. Interferometric instrumentation is demanding and involves critical variables that are required for Extremely Large Telescope (ELT) instrumentation, such as environmental properties, adaptive optics and cophasing over large structures of size comparable or larger than an ELT.

At the national level our team has a record of collaboration and spreading of interferometric know-how that has already resulted in a workshop and several refereed publications. The FCT 2006 funded project was the first project connected to ESO instrumentation with the joint participation of Porto (CAUP) and Lisbon (SIM and DOL). This national collaboration is expanded in the present project by including CENTRA, a key Portuguese research unit in astrophysics, which will contribute their gravity and black-hole physics know-how to the GRAVITY science case.

The present project is in line with the time-line of the VSI and GRAVITY instruments. In particular, for the time-scale of the project we seek funding for:
a) the construction of the GRAVITY acquisition camera;
b) the design studies of the VSI beam acquisition and calibration tools;
c) the development of the instruments science case and image reconstruction simulations.

A critical I aspect of the project's scientific success is to guarantee the funding for the construction of the GRAVITY acquisition camera, whose equipment budget was carefully negotiated to a bare minimum to be compatible with the resources allowed in the present project call that are much lower than the scale of efforts naturally involved in astrophysical instrument development.

Institutions & Research Units involved in the project:
- Fundação da Faculdade de Ciências (FFC/FC/UL)
- Centro de Astrofísica da Universidade do Porto (CAUP/UP)
- Instituto Superior Técnico (IST/UTL)
- Laboratório de Sistemas, Instrumentação e Modelação em Ciências e Tecnologias da Terra e do Espaço (SIM)
- Centro Multidisciplinar de Astrofísica (CENTRA/IST/UTL)
- Faculdade de Ciências da Universidade de Lisboa (FC/UL)

Project members in CAUP:
- Mercedes Filho

Funding institution
Fundação para a Ciência e a Tecnologia

Start: 1 February 2010
End: 31 December 2012