Abstract
We describe the fringe-packet tracking system used to equalize the
optical path lengths at the Infrared Optical Telescope Array
interferometer. The measurement of closure phases requires obtaining
fringes on three baselines simultaneously. This is accomplished by use
of an algorithm based on double Fourier interferometry for obtaining the
wavelength-dependent phase of the fringes and a group-delay tracking
algorithm for determining the position of the fringe packet. A
comparison of data acquired with and without the fringe-packet tracker
shows a factor of ~3 reduction of the error in the closure-phase
measurement. The fringe-packet tracker has been able so far to track
fringes with signal-to-noise ratios as low as 1.8 for stars as faint as
m_H=7.0.
Original language | English |
---|---|
Pages (from-to) | 5173-5179 |
Number of pages | 6 |
Journal | Applied Optics IP |
Volume | 44 |
Issue number | 25 |
DOIs | |
Publication status | Published - 1 Sept 2005 |