WP4.2: “Contribution to the development of an optimum co-phaser for the VLTI”
PI: Françoise Delplancke, ESO-D
In order to break the sensitivity limit of interferometry, co-phasing of the telescopes on a bright star is needed to stabilize the fringes on a neighboring object. Up to know most of the existing co-phasing devices have been designed and built to co-phase pairs (PRIMA) or triplets (FINITO) of telescopes. In the framework of the second generation of instruments for the VLTI and of space interferometers like DARWIN, co-phasing of 4 telescopes or more will be needed.
The role of this WP will be to reinforce the collaboration between the various European institutes and ESO for the development of this fundamental device. This work package will be divided into the following phases and milestones:
a) WP 4.2.1 - Phase 1 – FINITO and PRIMA commissioning data analysis
a. Goals: Systematic collection of fringe tracking (co-phasing) data during the commissioning phases of PRIMA and operation of FINITO on the VLTI. Recording and/or modeling of the disturbances as observed during this commissioning. Comparison of the sensitivity of both concepts (PRIMA and FINITO) to the disturbances. Analysis of these data in view of the needs for the extension of the co-phasing to 4 telescopes and of the needs of the VLTI 2nd generation instruments. Identification of the concept providing the best compromise between performance and robustness. The final goal is to provide detailed specifications for the VLTI new co-phaser for 4 telescopes, based on the PRIMA and FINITO experience.
b. Starting date: As soon as possible – January 1, 2009
c. Duration: 12 months
d. Participants: all, post-doc based at ESO
i. report on fringe tracking performance with PRIMA and FINITO
ii. refereed publications
iii. detailed specifications for a 4+ telescope beam combiner.