Characterizing closure-phase measurements at IOTA

Ragland, Sam; Traub, Wesley A.; Berger, J.‐P.; Millan-Gabet, R.; Monnier, John D.; Pedretti, E.; Schloerb, F. Peter; Carleton, N. P.; Haguenauer, Pierre; Kern, P.; Labeye, P.; Lacasse, M. G.; Malbet, Fabien; Rousselet-Perraut, K.

doi:10.1117/12.552447

Cited by 7 publications

(4 citation statements)

References 5 publications

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“…A preliminary report is in this volume. 5 On color, with a wide-band H filter, we find that the closure phase is independent of the color temperature of the target star, within measurement error. With the narrow-band filters, we find that the closure phase varies slightly, if at all, with filter choice, with the exception that the longest-wavelength narrow filter shows about a 10 • difference in closure phase when measured with 3 detector outputs compared to the corresponding 3 complementary outputs.…”

Section: Phase-closure Validationmentioning

confidence: 59%

“…The current integrated-optics 3-beam combiner was installed in November 2002, and has been used continuously since then. Some characteristics of this combiner are described in this volume by Ragland et al 5 Briefly, the combiner was built in Grenoble, and designed for H-band operation. The three telescope beams are focussed onto three single-mode fibers, and these fibers are bonded to the input end of the thin glass plate that contains the combiner.…”

Section: Integrated-optics 3-beam Combinermentioning

confidence: 99%

“…This paper reviews progress in science and technology at the Infrared Optical Telescope Array (IOTA), since the last such review, 1 some of which is reported in the present volume. 2,3,4,5,6 Briefly, IOTA is a long-baseline optical interferometer located at the Smithsonian Institution's Whipple Observatory on Mount Hopkins, AZ. It comprises three 45-cm diameter telescopes which can be positioned at 17 stations on an L-shaped track, where the arm lengths are 15 m toward the south-east and 35 m toward the north-east.…”

Section: Introductionmentioning

confidence: 99%

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IOTA: recent technology and science

Traub

Berger

Brewer

et al. 2004

New Frontiers in Stellar Interferometry

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Closure-phase science and technology are dominant features of the recent activity at IOTA. Our science projects include imaging several spectroscopic binary stars, imaging YSOs including Herbig AeBe stars, detecting asymmetries in a large sample of Mira stars, and measuring water shells around Miras. Many technology projects were pursued in order to make these science observations possible. These include installation of a third-generation integrated-optics 3-beam combiner (IONIC), completion of the real-time control system software, installation of fringe-packet tracking software, use of narrow sub-H band filters, validation of the phase-closure operation, development of CPLD control of the science camera (PICNIC) and star-tracker camera (LLiST), installation of a new star-tracker camera, expansion of the observing facility, and installation of new semi-automated optical alignment tools.

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Section: Phase-closure Validationmentioning

confidence: 59%

Section: Integrated-optics 3-beam Combinermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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IOTA: recent technology and science

Traub

Berger

Brewer

et al. 2004

New Frontiers in Stellar Interferometry

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“…In a crude approximation, r 0 = λ/α and τ 0 = 0.5 r 0 /v w (assuming dominance of ground wind speed), which yields r 0 = 17 cm and τ 0 = 16 ms. In the H band, in which the IONIC fiber beam combiner at IOTA operates, 5,6 and using the fact that r 0 ∝ λ 6/5 , λ H c = 1.65 µm so that r H 0 = 53 cm and τ H 0 = 50 ms. The telescopes at IOTA have an entrance pupil D = 45 cm which is of the same order of magnitude as r H 0 .…”

Section: Introductionmentioning

confidence: 99%

LLiST: a new-star tracker camera for tip-tilt correction at IOTA

Schüller

Lacasse²,

Lydon

et al. 2004

New Frontiers in Stellar Interferometry

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The tip-tilt correction system at the Infrared Optical Telescope Array (IOTA) has been upgraded with a new star tracker camera. The camera features a backside-illuminated CCD chip offering doubled overall quantum efficiency and a four times higher system gain compared to the previous system. Tests carried out to characterize the new system showed a higher system gain with a lower read-out noise electron level. Shorter read-out cycle times now allow to compensate tip-tilt fluctuations so that their error imposed on visibility measurements becomes comparable to, and even smaller than, that of higher-order aberrations.

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The Importance of Phase in Nulling Interferometry and a Three‐Telescope Closure‐Phase Nulling Interferometer Concept

Danchi¹,

Rajagopal²,

Kuchner³

et al. 2006

ApJ

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We discuss the theory of the Bracewell nulling interferometer and explicitly demonstrate that the phase of the "white light" null fringe is the same as the phase of the bright output from an ordinary stellar interferometer. As a consequence a "closure phase" exists for a nulling interferometer with three or more telescopes. We calculate the phase offset as a function of baseline length for an Earth-like planet around the Sun at 10 pc, with a contrast ratio of 10 −6 at 10 µm. The magnitude of the phase due to the planet is ∼ 10 −6 radians, assuming the star is at the phase center of the array. Although this is small, this phase may be observable in a three-telescope nulling interferometer that measures the closure phase. We propose a simple non-redundant three-telescope nulling interferometer that can perform this measurement. This configuration is expected to have improved characteristics compared to other nulling interferometer concepts, such as a relaxation of pathlength tolerances, through the use of the "ratio of wavelengths" technique, a closure phase, and better discrimination between exodiacal dust and planets.

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Characterizing closure-phase measurements at IOTA

Cited by 7 publications

References 5 publications

IOTA: recent technology and science

IOTA: recent technology and science

LLiST: a new-star tracker camera for tip-tilt correction at IOTA

The Importance of Phase in Nulling Interferometry and a Three‐Telescope Closure‐Phase Nulling Interferometer Concept

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