Calibrators for optical interferometry

Christian Hummel
European Southern Observatory
Karl-Schwarzschildstr. 2
D-85748 Garching
GERMANY

Phone: +49 89 3200 6151
Email: chummel@eso.org

Background

Interferometers measure amplitude and phase of the complex visibility, which, by definition, are unity and zero, respectively, for an ideal instrument in the absence of the atmosphere observing an unresolved star through a monochromatic filter. In reality, the measured amplitude is always smaller due to atmospheric turbulence and instrumental degradation, thus the amplitude measured on a science target has to be normalized by the amplitude measured on a calibrator.

Calibrators are rarely unresolved, and if bright ones are needed, they tend to be big enough to require good estimates of their angular diameter. These are extracted from their photometry, assuming they are described by a single photosphere of a non-rotating star.

Thus, we have two issues in this business: first, to define suitable selection rules based on astrophysical insight, and second, to share data on calibrators especially if they turn out to be unsuitable for any reason.

Service area

Resources
Here we compile a list of resources to aid in the selection of calibrators. Clicking a link will open the resource in a new window.

Publications
Papers related to the topic
  • A catalogue of calibrator stars for long baseline stellar interferometry (Borde et al. 2002)
  • A catalog of bright calibrator stars for 200-m baseline near-infrared stellar interferometry (Merand et al. 2006)
  • The Palomar Testbed Interferometer Calibrator Catalog (van Belle et al. 2008)
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    Projects
    Ongoing projects to improve the data bases

    Discussion
    Areas of concern, comments, issues...


    Last updated: 9 July 2015 by Christian A. Hummel