Time filter

Source Type

Pott J.-U.,Max Planck Institute for Astronomy | Pott J.-U.,California Association for Research in Astronomy | Pott J.-U.,University of California at Los Angeles | Woillez J.,Max Planck Institute for Astronomy | And 24 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

Recently, the Keck interferometer was upgraded to do self-phase-referencing (SPR) assisted K-band spectroscopy at R ∼ 2000. This means, combining a spectral resolution of 150 km/s with an angular resolution of 2.7 mas, while maintaining high sensitiviy. This SPR mode operates two fringe trackers in parallel, and explores several infrastructural requirements for off-axis phase-referencing, as currently being implemented as the KI-ASTRA project. The technology of self-phasereferencing opens the way to reach very high spectral resolution in near-infrared interferometry. We present the scientific capabilities of the KI-SPR mode in detail, at the example of observations of the Be-star 48 Lib. Several spectral lines of the cirumstellar disk are resolved. We describe the first detection of Pfund-lines in an interferometric spectrum of a Be star, in addition to Br γ . The differential phase signal can be used to (i) distinguish circum-stellar line emission from the star, (ii) to directly measure line asymmetries tracing an asymetric gas density distribution, (iii) to reach a differential, astrometric precision beyond single-telescope limits sufficient for studying the radial disk structure. Our data support the existence of a radius-dependent disk density perturbation, typically used to explain slow variations of Be-disk hydrogen line profiles. © 2010 SPIE.

Agency: NSF | Branch: Continuing grant | Program: | Phase: ADVANCED TECHNOLOGIES & INSTRM | Award Amount: 1.87M | Year: 2010

The goal of correcting the Earths atmospheric effects on astronomical images has seen considerable success through the use of laser guide star adaptive optics (AO) systems that provide a quantitative measure of the turbulence distributed over the aperture of a large telescope. However, laser systems by themselves cannot detect the ensemble shift in an objects image that is induced by the atmosphere, and the encircled energy in a diffraction-limited spot could be increased by more than 40% if this correction were made. Such a tip/tilt correction is only available through the use of a natural guide star - a rather bright natural star included in the telescope field of view - in tandem with the laser projection system. The near-IR tip/tilt sensor being constructed by Dr. Peter Wizinowich and collaborators of the California Association for Research in Astronomy for the Keck 10-m telescope on Mauna Kea, Hawaii will accomplish this goal. By working in the K (2.2 micron wavelength) atmospheric transmission band, the planned system will provide high bandwidth (up to 1 kHz) tip/tilt information using one to three stars in a 2 arcminute diameter area, and enable corrections over that entire field of view. Additionally, focus corrections are available at a much higher time resolution than for standard schemes.

The Keck telescopes are arguably the most advanced, reliable, and scientifically productive large-telescope AO systems available anywhere in the world. Scientists and technical staff at the managing institutions are among the most capable in the world, and the mountaintop is an outstanding observing site. Up to 30% of observing time is available to the general community through various means, so improvements in the imaging capabilities of the telescopes through mechanisms like near-IR tip/tilt correction systems benefit all of U.S. astronomy. Funding for this work is being provided by NSFs Division of Astronomical Sciences through its Advanced Technologies and Instrumentation program.

Agency: NSF | Branch: Standard Grant | Program: | Phase: MAJOR RESEARCH INSTRUMENTATION | Award Amount: 4.00M | Year: 2014

While astronomical images can offer breathtaking records of the appearance of the Universe, far greater information is obtained by dividing a light beam according to color (a technique known as spectroscopy). This approach can yield important details about the physical properties of the source: its temperature, chemical composition, density, mass, and velocity, among others. Constructing very efficient, wide spectral coverage, high-resolution mapping spectrographs is therefore an effective approach to getting the most from our very largest ground-based telescopes. Dr. H. Lewis (California Association for Research in Astronomy together with the California Institute of Technology and the University of California) proposes to complete the development of the Keck Cosmic Web Imager spectrograph for the 10-m Keck II telescope atop Mauna Kea, Hawaii with new optics optimized for the red portion of the spectrum. The final instrument will provide an extraordinary platform for carrying out sensitive assessments of galaxy formation and evolution in the first few hundred million years after the Big Bang, to study the interstellar medium in external galaxies, to probe star clusters and nebulae in our own Milky Way galaxy, and to track the process of star formation within those clusters.

The Keck Cosmic Web Imager (KCWI) is designed to provide seeing-limited visible band, integral field spectroscopy with moderate to high spectral resolution (up to R = 20,000), selectable slicer scales and fields of view, high efficiency, and excellent sky subtraction. KCWI will benefit from the Keck II telescopes large, 10-m aperture and excellent site, providing a dual-channel, modular implementation. The blue channel of KCWI is nearly complete; the red channel to be funded through this proposal will extend the spectral coverage to the entire optical window from 3500 to 10500 angstroms and enable scientists to address several of the key questions relating to the process of the formation and evolution of external galaxies, and thereby of the development of matter in the universe.

Funding for the development of the red channel of the Keck Cosmic Web Imager is being provided by NSFs Division of Astronomical Sciences through its participation in the Major Research Instrumentation program.

Agency: NSF | Branch: Continuing grant | Program: | Phase: ADVANCED TECHNOLOGIES & INSTRM | Award Amount: 386.30K | Year: 2016

To get the sharpest images of planets, stars and galaxies, astronomers must use innovative techniques that correct for the blurring of images caused by turbulence in the earths atmosphere. One of the most exciting uses of this technology is imaging planets around nearby stars. This team aims to build a device that works using infrared light from the host star (the star that the planet orbits). The device will be used on one of the worlds largest telescopes, the Keck II telescope on Maunakea, Hawaii. The system works by rapidly changing the shape of mirrors inside the instrument to counteract the effect of ripples in the earths atmosphere. The principal investigator, along with a postdoctoral researcher, summer interns, and graduate and undergraduate students from Hawaii and California, will search for planets around 150 small dwarf stars. Their results will be made available to the broader science community through the Keck Data Archive.

Driven by the scientific desire to study young planetary systems around low-mass M-dwarfs, and the practical need to develop near-infrared (NIR) wavefront sensing and adaptive optics (AO) capabilities for the upcoming generation of 30 meter class segmented-mirror telescopes, the proposers seek to produce a system that operates in the L-band for the Keck observatory. The IR detector technology needed for such a system now exists (in large part through funding by NSF) and will be used by the proposers to build a near-IR, high-order, pyramid wavefront sensor for the Keck II telescope. This system will then be used to conduct an L-band (3 micron) coronagraphic imaging survey of ~150 M dwarfs with the Keck facility instrument, NIRC2. The team will conduct follow-up low-resolution slit spectroscopy observations of any exoplanet candidates found in the L-band survey. Note that M-dwarfs are too faint to observe with sufficient contrast and spatial resolution to detect (even massive) exoplanets with existing optical AO systems. The development of the proposed NIR wavefront sensing system at Keck may be viewed as an enabling technology that could lead to the fabrication of similar units at other, publicly available observatories. It should also be noted that NIR wavefront sensing can be used to extend the performance of natural guide star AO systems to fainter targets, and to increase the sky coverage to regions where only optically obscured or very red guide stars are available.

Agency: NSF | Branch: Standard Grant | Program: | Phase: ADVANCED TECHNOLOGIES & INSTRM | Award Amount: 684.00K | Year: 2012

Although the advent of adaptive optics (AO) has ushered in an era of dramatic discoveries that make use of the superb resolution of large ground-based telescopes, lack of knowledge of the point spread function (PSF) still stands as a fundamental limitation. Extragalactic, galactic and solar system AO science programs currently rely on non-synchronous PSF calibration stars, which results in increased random and systematic errors in astrometry, photometry, morphology and kinematics. The future of quantitative AO science, and the goal of the project proposed by Dr. Peter Wizinowich and his collaborators at the California Association for Research in Astronomy, lies in reconstructing synchronous PSF knowledge based on real-time telemetry collected from the telescope and AO system.

This proposal will develop PSF determination tools for on-axis both natural and laser guide-star AO science observations and demonstrate the quantitative science improvements that can be realized with these tools using the 10-m diameter Keck telescopes. The significantly improved capabilities produced through this program will be directly available to astronomers at the California Institute of Technology, the University of California, and the University of Hawaii through their time allocation committees, while the entire U.S. community will benefit due to their access to Keck through NASA and the NSF Telescope System Instrumentation Program. Moreover, success at the Keck Observatory would enable PSF determination to become a reality for AO on large telescopes worldwide, as the algorithms and techniques will be made publically available. Keck will also reinforce its role in the training of AO experts and continue to offer educational programs and services to work with local residents, educators and especially students, including its strong participation in the Akamai Workforce Initiative aimed at local Hawaiian students.

Funding for the development of real-time PSF assessment techniques is being provided by NSFs Division of Astronomical Sciences through its Advanced Technologies and Instrumentation program.

Agency: NSF | Branch: Standard Grant | Program: | Phase: MAJOR RESEARCH INSTRUMENTATION | Award Amount: 1.35M | Year: 2015

The Near-Infrared Spectrometer (NIRSPEC), which is designed to examine infrared light emitted by stars and galaxies, has been used for hundreds of scientific studies since it was commissioned for use at the Keck II telescope atop Maunakea, Hawaii in 1999. A team of scientists and engineers from the California Association for Research in Astronomy and the University of California, Los Angeles propose to upgrade this aging instrument. The upgrade will improve NIRSPECs sensitivity by installing modern detectors and improve its stability through a combination of upgrades to electronics, software, and the system that allows NIRSPEC to lock onto and track stars. This will give the U.S. astronomical community an unique tool to push the frontiers of knowledge in numerous areas, including understanding the clouds of gas that form new stars, the oldest and most distant parts of the universe, and asteroids in our solar system. The student participants in this project will gain skill in building complex optical instruments that will be equally well applied to future projects in astronomy and the commercial sector.

The Near-Infrared Spectrometer (NIRSPEC), a 1-5 micron moderate resolution instrument that has been operational on the 10 m Keck II telescope since 1999, has provided data for over 350 papers and 35 Ph.D. theses on a wide range of topics. The proposed work will extend the life of this instrument as well as improve its sensitivity, stability, and spectral resolution by upgrading the main spectrograph detector, adding a new slit-viewing camera, upgrading the control electronics and software, and modifying the grating mechanism. The upgraded NIRSPEC will enable a wide variety of scientific studies identified as high priority in the most recent Decadal Survey, ranging from protostellar disks and exoplanet atmospheres to solar system objects and the high-redshift universe. It will be a unique capability for the U.S. astronomical community at one of the highest impact astronomical facilities.

Agency: NSF | Branch: Continuing grant | Program: | Phase: ADVANCED TECHNOLOGIES & INSTRM | Award Amount: 967.85K | Year: 2013

An exciting benefit of the semiconductor revolution that has had tremendous impact on astronomy at optical and infrared wavelengths has been the development of ever more sensitive array detectors. These arrays are delivering hitherto-unimagined improvements in observing efficiency and enabling new and exciting science projects. This project plans to carry out an upgrade to the array detector in the OSIRIS instrument deployed on the 10 meter Keck telescope on top of Mauna Kea. The current science detector, called a Hawaii-2 (H2), will be replaced with a Hawaii-2RG (H2RG), which has a number of technical features that significantly enhance its performance.

The OSIRIS instrument is an integral-field spectrograph (IFS) fed by adaptive optics (AO); there are only a few such combinations in operation worldwide at the moment. The non-common-path error is low, less than any other IFS, preserving the diffraction-limited point-spread-function delivered by the Keck AO system. This has been a very productive combination scientifically. The older array detector may be at some risk for failure simply due to its age; the newer array will offer higher sensitivity (twice as high at many wavelengths) and reduced detector artifacts. It will have improved multiplexer performance that will greatly reduce channel-to-channel crosstalk and eliminate a reset anomaly that degrades some of the readouts in a commonly-used mode of observing.

The Keck telescopes have had a major impact on astronomy education, as evidenced by the 240 PhD theses (now averaging 20/year) produced as of early 2012 using Keck data. Many leaders in U.S. astronomy are included in this number. The WMKO (Keck Observatory) provides many graduate students and post-doctoral fellows direct access to state-of-the-art instrumentation, including adaptive optics. The OSIRIS upgrade project in particular will involve a graduate student at UCLA.

Funding for this project is being provided by NSFs Division of Astronomical Sciences through its Advanced Technologies and Instrumentation program.

Loading California Association for Research in Astronomy collaborators
Loading California Association for Research in Astronomy collaborators