First Closure Phase Measurements at the CHARA Array

CHARA Array Website
First Fringes with MIRC | First Closure Phase at CHARA Array | First 4-Telescope Fringes

From John Monnier, University of Michigan
15 September 2005.

We'd like to announce first closure phase results with the CHARA Array, made possible using the new Michigan Infrared Combiner (MIRC). First closure phases were observed (visually) on UT2005Sep14 on Bet Tau at 5:30am local time, however no data was recorded. The data presented here is from the next night UT 2005Sep15 where many fringe sets were recorded on Bet Tau in H-band using CHARA telescopes S1-S2-W1, corresponding to baselines of roughly 30m, 180m, and 210m.

I've attached a few files showing the three simultaneous fringes and dispersed power spectra, and the first closure phase reduction. For H=1.9mag source during poor seeing, the closure phase error is ~0.9 degs for a 1-second average over all H-band spectral channels.

I've also attached a group picture of those present during the first closure phase detection (Ettore Pedretti, Nathalie Thureau, Ming Zhao, PJ Goldfinger (not shown, behind camera) and John Monnier). I also thank Phil Muirhead, Scott Webster, and Ajay Tannirkulman from Michigan and Jean-Philippe Berger and Rafael Millan-Gabet. Lastly, nothing would be possible without the dedicated Georgia State CHARA crew for creating (and continuously improving) the wonderful and powerful CHARA array.

For further details also see John Monnier's Homepage

Funding for the CHARA Array has been provided by the National Science Foundation, the W. M. Keck Foundation, the David and Lucile Packard Foundation, and Georgia State University.

Funding for Michigan Infrared Combiner has been provided by the University of Michigan and the National Science Foundation.

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MS 301-451, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109

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