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Title: Angular Differential Imaging: a Powerful High-Contrast Imaging Technique

Abstract

Angular differential imaging is a high-contrast imaging technique that reduces speckle noise from quasi-static optical aberrations and facilitates the detection of faint nearby companions. A sequence of images is acquired with an altitude/azimuth telescope, the instrument rotator being turned off. This keeps the instrument and telescope optics aligned, stabilizes the instrumental PSF and allows the field of view to rotate with respect to the instrument. For each image, a reference PSF obtained from other images of the sequence is subtracted. All residual images are then rotated to align the field and are median combined. Observed performances are reported for Gemini Altair/NIRI data. Inside the speckle dominated region of the PSF, it is shown that quasi-static PSF noise can be reduced by a factor {approx}5 for each image subtraction. The combination of all residuals then provides an additional gain of the order of the square root of the total number of images acquired. To our knowledge, this is the first time an acquisition strategy and reduction pipeline designed for speckle attenuation and high contrast imaging is demonstrated to significantly get better detection limits with longer integration times at all angular separations. A PSF noise attenuation of 100 was achieved from 2-hourmore » long sequences of images of Vega, reaching a 5-sigma contrast of 20 magnitudes for separations greater than 7''. This technique can be used with currently available instruments to search for {approx} 1 M{sub Jup} exoplanets with orbits of radii between 50 and 300 AU around nearby young stars. The possibility of combining the technique with other high-contrast imaging methods is briefly discussed.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
887287
Report Number(s):
UCRL-JRNL-216949
Journal ID: ISSN 0004-637X; ASJOAB; TRN: US200618%%51
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 641; Journal Issue: 1
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; ATTENUATION; DETECTION; OPTICS; PIPELINES; SENSITIVITY; STARS; TELESCOPES

Citation Formats

Marois, C, Lafreniere, D, Doyon, R, Macintosh, B, and Nadeau, D. Angular Differential Imaging: a Powerful High-Contrast Imaging Technique. United States: N. p., 2005. Web.
Marois, C, Lafreniere, D, Doyon, R, Macintosh, B, & Nadeau, D. Angular Differential Imaging: a Powerful High-Contrast Imaging Technique. United States.
Marois, C, Lafreniere, D, Doyon, R, Macintosh, B, and Nadeau, D. Mon . "Angular Differential Imaging: a Powerful High-Contrast Imaging Technique". United States. doi:. https://www.osti.gov/servlets/purl/887287.
@article{osti_887287,
title = {Angular Differential Imaging: a Powerful High-Contrast Imaging Technique},
author = {Marois, C and Lafreniere, D and Doyon, R and Macintosh, B and Nadeau, D},
abstractNote = {Angular differential imaging is a high-contrast imaging technique that reduces speckle noise from quasi-static optical aberrations and facilitates the detection of faint nearby companions. A sequence of images is acquired with an altitude/azimuth telescope, the instrument rotator being turned off. This keeps the instrument and telescope optics aligned, stabilizes the instrumental PSF and allows the field of view to rotate with respect to the instrument. For each image, a reference PSF obtained from other images of the sequence is subtracted. All residual images are then rotated to align the field and are median combined. Observed performances are reported for Gemini Altair/NIRI data. Inside the speckle dominated region of the PSF, it is shown that quasi-static PSF noise can be reduced by a factor {approx}5 for each image subtraction. The combination of all residuals then provides an additional gain of the order of the square root of the total number of images acquired. To our knowledge, this is the first time an acquisition strategy and reduction pipeline designed for speckle attenuation and high contrast imaging is demonstrated to significantly get better detection limits with longer integration times at all angular separations. A PSF noise attenuation of 100 was achieved from 2-hour long sequences of images of Vega, reaching a 5-sigma contrast of 20 magnitudes for separations greater than 7''. This technique can be used with currently available instruments to search for {approx} 1 M{sub Jup} exoplanets with orbits of radii between 50 and 300 AU around nearby young stars. The possibility of combining the technique with other high-contrast imaging methods is briefly discussed.},
doi = {},
journal = {Astrophysical Journal},
number = 1,
volume = 641,
place = {United States},
year = {Mon Nov 07 00:00:00 EST 2005},
month = {Mon Nov 07 00:00:00 EST 2005}
}
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