Hinkley, Sasha and Oppenheimer, Ben R. and Zimmerman, Neil and Brenner, Douglas and Parry, Ian R. and Crepp, Justin R. and Vasisht, Gautam and Ligon, Edgar and King, David and Soummer, Rémi and Sivaramakrishnan, Anand and Beichman, Charles and Shao, Michael and Roberts, Lewis C., Jr. and Bouchez, Antonin and Dekany, Richard and Pueyo, Laurent and Roberts, Jennifer E. and Lockhart, Thomas and Zhai, Chengxing and Shelton, Chris and Burruss, Rick (2011) A New High Contrast Imaging Program at Palomar Observatory. Publications of the Astronomical Society of the Pacific, 123 (899). pp. 74-86. ISSN 0004-6280 http://resolver.caltech.edu/CaltechAUTHORS:20110302-102607868
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We describe a new instrument that forms the core of a long-term high contrast imaging program at the 200 inch (5 m) Hale Telescope at Palomar Observatory. The primary scientific thrust is to obtain images and lowresolution spectroscopy of brown dwarfs and young exoplanets of several Jupiter masses in the vicinity of stars within 50 pc of the Sun. The instrument is a microlens-based integral field spectrograph integrated with a diffractionlimited, apodized-pupil Lyot coronagraph. The entire combination is mounted behind the Palomar adaptive optics (AO) system. The spectrograph obtains imaging in 23 channels across the J and H bands (1.06–1.78 μm). The image plane of our spectrograph is subdivided by a 200 × 200 element microlens array with a plate scale of 19.2 mas per microlens, critically sampling the diffraction-limited point-spread function at 1.06 μm. In addition to obtaining spectra, this wavelength resolution allows suppression of the chromatically dependent speckle noise, which we describe. In addition, we have recently installed a novel internal wave front calibration system that will provide continuous updates to the AO system every 0.5–1.0 minutes by sensing the wave front within the coronagraph. The Palomar AO system is undergoing an upgrade to a much higher order AO system (PALM-3000): a 3388-actuator tweeter deformable mirror working together with the existing 241-actuator mirror. This system, the highest-resolution AO corrector of its kind, will allow correction with subapertures as small as 8.1 cm at the telescope pupil using natural guide stars. The coronagraph alone has achieved an initial dynamic range in the H band of 2 × 10^(-4) at 1″, without speckle noise suppression. We demonstrate that spectral speckle suppression provides a factor of 10–20 improvement over this, bringing our current contrast at 1″ to ~2 × 10^(-5). This system is the first of a new generation of apodized-pupil coronagraphs combined with high-order adaptive optics and integral field spectrographs (e.g., GPI, SPHERE, HiCIAO), and we anticipate that this instrument will make a lasting contribution to high-contrast imaging in the Northern Hemisphere for years.
|Additional Information:||© 2011 The Astronomical Society of the Pacific. Received 2010 September 25; accepted 2010 November 12; published 2011 January 4. This work was performed in part under contract with the California Institute of Technology, funded by NASA through the Sagan Fellowship Program. A portion of this work is supported by the National Science Foundation under grant nos. AST-0908497, AST-0804417, 0334916, 0215793, and 0520822, as well as grant NNG05GJ86G from the National Aeronautics and Space Administration under the Terrestrial Planet Finder Foundation Science Program. This work has been partially supported by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California. Santa Cruz, under cooperative agreement AST-9876783. A portion of the research in this article was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration and was funded by internal Research and Technology Development funds. We are grateful to the efforts of Derek Ives, Stewart McLay, Andrew Vick, and the other skilled engineers at the UK Astronomy Technology Centre for their configuration of the detector control software. We also are thankful to Chris Shelton for help in the design of the Atmospheric Dispersion Correcting prisms. Our team is also grateful to the Cordelia Corporation, Hilary and Ethel Lipsitz, the Vincent Astor Fund, Judy Vale, and the Plymouth Hill Foundation.|
|Official Citation:||A New High Contrast Imaging Program at Palomar Observatory Sasha Hinkley, Ben R. Oppenheimer, Neil Zimmerman, Douglas Brenner, Ian R. Parry, Justin R. Crepp, Gautam Vasisht, Edgar Ligon, David King, Rémi Soummer, Anand Sivaramakrishnan, Charles Beichman, Michael Shao, Lewis C. Roberts Jr., Antonin Bouchez, Richard Dekany, Laurent Pueyo, Jennifer E. Roberts, Thomas Lockhart, Chengxing Zhai, Chris Shelton, Rick Burruss Publications of the Astronomical Society of the Pacific Vol. 123, No. 899 (January 2011), pp. 74-86 Published by: The University of Chicago Press on behalf of the Astronomical Society of the Pacific Stable URL: http://www.jstor.org/stable/10.1086/658163|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||03 Mar 2011 16:48|
|Last Modified:||03 Mar 2011 16:48|
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