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Proceedings Article

First results from fringe tracking with the PRIMA fringe sensor unit

[+] Author Affiliations
J. Sahlmann

Observatoire de Genève (Switzerland) and European Southern Observatory (Germany) and European Southern Observatory (Chile)

R. Abuter, S. Ménardi, C. Schmid, N. Di Lieto, F. Delplancke, R. Frahm, N. Gomes, S. Lévêque, T. Phan Duc, G. van Belle

European Southern Observatory (Germany)

P. Haguenauer, S. Morel, N. Schuhler

European Southern Observatory (Chile)

A. Mueller

European Southern Observatory (Germany) and Max-Planck-Institut fur Astronomie (Germany)

Proc. SPIE 7734, Optical and Infrared Interferometry II, 773422 (July 21, 2010); doi:10.1117/12.856896
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From Conference Volume 7734

  • Optical and Infrared Interferometry II
  • William C. Danchi; Françoise Delplancke; Jayadev K. Rajagopal
  • San Diego, California, USA | June 27, 2010


The fringe sensor unit (FSU) is the central element of the phase referenced imaging and micro-arcsecond astrometry (PRIMA) dual-feed facility for the Very Large Telescope interferometer (VLTI). It has been installed at the Paranal observatory in August 2008 and is undergoing commissioning and preparation for science operation. Commissioning observations began shortly after installation and first results include the demonstration of spatially encoded fringe sensing and the increase in VLTI limiting magnitude for fringe tracking. However, difficulties have been encountered because the FSU does not incorporate real-time photometric correction and its fringe encoding depends on polarisation. These factors affect the control signals, especially their linearity, and can disturb the tracking control loop. To account for this, additional calibration and characterisation efforts are required. We outline the instrument concept and give an overview of the commissioning results obtained so far. We describe the effects of photometric variations and beam-train polarisation on the instrument operation and propose possible solutions. Finally, we update on the current status in view of the start of astrometric science operation with PRIMA.

© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

J. Sahlmann ; R. Abuter ; S. Ménardi ; C. Schmid ; N. Di Lieto, et al.
"First results from fringe tracking with the PRIMA fringe sensor unit", Proc. SPIE 7734, Optical and Infrared Interferometry II, 773422 (July 21, 2010); doi:10.1117/12.856896; http://dx.doi.org/10.1117/12.856896

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