In the near future, the installation of the PRIMA facility will enrich the current generation of VLTI instruments with off-axis phase referencing for imaging and astrometry. In parallel, two European consortia are pursuing the design of the second generation of VLTI instrumentation (GRAVITY & MATISSE). The goal of this work package is to support these activities, especially with respect to the phase reference imaging mode. This will be done through a phased approach to progressively increase the capabilities of the array in this observing mode. This effort is driven by the access to faint object science and high precision astrometric measurements. The role of the WP will be the definition/coordination of the tasks and the reporting.

a.      WP4.1.1 Evaluation of the Paranal atmospheric parameters for high precision fringe tracking: The first generation instrumentation of the VLTI has shown that the atmosphere above Paranal has original properties with respect to high angular resolution observations. The goal of this post-doc will be to assemble a complete picture of the current status of the atmospheric turbulence at Paranal, specifically on the properties of interest for interferometry (piston spectrum, turbulence sructure, external scale,...). The foreseen work will first include a synthesis of the different measurements already available in the scientific literature and ESO technical reports, and the re-analysis of archive data (VINCI, MIDI, AMBER) from the point-of-view of atmosphere characterization. In addition, an extensive series of dedicated technical measurements with the available instrumentation and the Auxiliary Telescopes will be obtained at Paranal. The deliverables will be a report and a refereed publication that will serve as a fiducial for the control loop design and daily operation of the VLTI fringe trackers, both with VLTI1 and VLTI2 instruments. The selected post-doc will be encouraged to conduct an active research of her/his choice in parallel to this work. This post-doc will be based in Paris (GRAVITY fringe tracker team), with foreseen extended stays in Nice (MATISSE team) and at ESO (Garching and Paranal).

Schedule: job advertisement in Autumn 2009, start in Winter 2009-2010. 

b.      WP4.1.2 Assessment of the VLTI behavior for MIDI and AMBER operations with PRIMA. The operation of the VLTI in dual-field mode with PRIMA represents an important step in the development of the array, and simultaneously a significant increase of its complexity. The goal of this work package is to assess the possibilities and limitations of the VLTI infrastructure for PRIMA, and therefore facilitate its routine operation. The work program of this post-doc will include the analysis of archival data from first generation instruments (VINCI, MIDI, AMBER) and of existing studies, together with additional in-situ measurements. In this process, a "clean-up" of the existing data processing software could be necessary to allow dual field data analysis.  The conclusions of this study will also contribute to the preparation of the second generation of VLTI instrumentation that will be developed further in WP4.1.3. We propose that this post-doc is based in Leiden, with close interactions with the MIDI and AMBER instrument teams, as well as visits to ESO.

Schedule: job advertisement in Autumn 2010, start in Winter 2010-2011.

c.      WP4.1.3 Preparing the VLTI for its second generation instrumentation. The goal of this program is to facilitate the first observations of the second generation VLTI instruments (MATISSE, VSI, GRAVITY), and therefore reduce the delay between their “first light” (expected in 2013) and the routine scientific observations. Following the work done for WP4.1.2, this post-doc will prepare the installation of VLTI2 instruments through a targeted evaluation of the relevant environmental parameters, and the proposition of corrective actions (if necessary). The program will include a characterization of the VLTI tunnel seeing in the context of dual field, and the identification of methods to mitigate its effects. This will be done in practice using the available first generation instrumentation including PRIMA. In addition to his/her technical work, the post-doc will also explore the first astrophysical applications of dual-field operation, in close interaction with the instrument teams. Scientifically, the PRIMA facility will provide an increased sensitivity when a nearby bright reference source is available, and improve the imaging capabilities of all instruments. We propose that this post-doc is based at MPIA in Heidelberg, with continued interaction with the VLTI2 instrument teams.