Recursos de colección

Caltech Authors (171.365 recursos)

Repository of works by Caltech published authors.

Group = Infrared Processing and Analysis Center (IPAC)

Mostrando recursos 1 - 20 de 2.551

  1. SMART precision interferometry at 794 nm

    Monnier, J. D.; Berger, J.-P.; Millan-Gabet, R.; Traub, W. A.; Carleton, N. P.; Pedretti, E.; Coldwell, C. M.; Papaliolios, C. D.
    Single-mode fibers have been used in the near-infrared to dramatically reduce calibration error for long-baseline interferometry. We have begun an effort to apply the advantages of spatial filtering at visible wavelengths for precision measurements of pulsating Cepheids using the IOTA interferometer. Rather than employing photometric taps to calibrate fluctuating coupling efficiency, we are using an "asymmetric" coupler which allows this calibration to be done without losing photons. The Single-Mode Asymmetric Recombination Technique (SMART) experiment has finished lab-testing, and has been installed at IOTA for full commissioning in Summer 2002. We report the results of lab characterization and first sky tests,...

  2. Molecular gas in AzTEC/C159: a star-forming disk galaxy 1.3 Gyr after the Big Bang

    Jiménez-Andrade, E. F.; Capak, P. L.
    We studied the molecular gas properties of AzTEC/C159, a star-forming disk galaxy at z = 4.567, in order to better constrain the nature of the high-redshift end of the submillimeter-selected galaxy (SMG) population. We secured ^(12)CO molecular line detections for the J = 2 →1 and J = 5 →4 transitions using the Karl G. Jansky Very Large Array (VLA) and the NOrthern Extended Millimeter Array (NOEMA) interferometer. The broad (FWHM ~ 750 km s^(−1)) and tentative double-peaked profiles of the two ^(12)CO lines are consistent with an extended molecular gas reservoir, which is distributed in a rotating disk, as...

  3. First Keck Interferometer measurements in self-phase referencing mode: spatially resolving circum-stellar line emission of 48 Lib

    Pott, J.-U.; Akeson, R. L.; Hillenbrand, L. A.; Millan-Gabet, R.; Colavita, M. M.; Felizardo, C.; Herstein, J.
    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...

  4. PIONIER: a visitor instrument for VLTI

    Berger, J.-P.; Millan-Gabet, R.; Traub, W.
    PIONIER is a 4-telescope visitor instrument for the VLTI, planned to see its first fringes in 2010. It combines four ATs or four UTs using a pairwise ABCD integrated optics combiner that can also be used in scanning mode. It provides low spectral resolution in H and K band. PIONIER is designed for imaging with a specific emphasis on fast fringe recording to allow closure-phases and visibilities to be precisely measured. In this work we provide the detailed description of the instrument and present its updated status.

  5. Electric field conjugation with the project 1640 coronagraph

    Cady, Eric; Baranec, Christoph; Beichman, Charles; Dekany, Richard; Hale, David; Hillenbrand, Lynne; Hinkley, Sasha
    The Project 1640 instrument on the 200-inch Hale telescope at Palomar Observatory is a coronagraphic instru- ment with an integral eld spectrograph at the back end, designed to nd young, self-luminous planets around nearby stars. To reach the necessary contrast for this, the PALM-3000 adaptive optics system corrects for fast atmospheric speckles, while CAL, a phase-shifting interferometer in a Mach-Zehnder con guration, measures the quasistatic components of the complex electric eld in the pupil plane following the coronagraphic stop. Two additional sensors measure and control low-order modes. These eld measurements may then be combined with a system model and data...

  6. Planet Formation Imager (PFI): science vision and key requirements

    Kraus, Stefan; Ciardi, David; Millan-Gabet, Rafael
    The Planet Formation Imager (PFI) project aims to provide a strong scientific vision for ground-based optical astronomy beyond the upcoming generation of Extremely Large Telescopes. We make the case that a breakthrough in angular resolution imaging capabilities is required in order to unravel the processes involved in planet formation. PFI will be optimised to provide a complete census of the protoplanet population at all stellocentric radii and over the age range from 0.1 to ~100 Myr. Within this age period, planetary systems undergo dramatic changes and the final architecture of planetary systems is determined. Our goal is to study the...

  7. Planet formation imager: project update

    Monnier, John D.; Ciardi, David
    The Planet Formation Imager (PFI) is a near- and mid-infrared interferometer project with the driving science goal of imaging directly the key stages of planet formation, including the young proto-planets themselves. Here, we will present an update on the work of the Science Working Group (SWG), including new simulations of dust structures during the assembly phase of planet formation and quantitative detection efficiencies for accreting and non-accreting young exoplanets as a function of mass and age. We use these results to motivate two reference PFI designs consisting of a) twelve 3m telescopes with a maximum baseline of 1.2km focused on...

  8. Enhancement of the Spitzer Infrared Array Camera (IRAC) distortion correction for parallax measurements

    Lowrance, Patrick J.; Carey, Sean J.; Ingalls, James G.; Surace, Jason A.; Capak, Peter; Stauffer, John; Beichman, Chas; Shupe, David; Kirkpatrick, J. Davy
    The Spitzer Space Telescope Infrared Array (IRAC) offers a rare opportunity to measure distances and determine physical properties of the faintest and coldest brown dwarfs. The current distortion correction is a 3rd order polynomial represented by TAN-SIP parameters within the headers. The current correction, good to 100 mas, was derived from deep imaging, using marginally resolved galaxies in some cases, and has remained stable throughout both the cryogenic and warm mission. Using recent Spitzer calibration observations mapped to HST/ACS calibration observations of 47 Tuc with an absolute accuracy good to 1 mas, we are working towards a possible 5th order...

  9. Estimate low- and high-order wavefront using P1640 calibrator measurements

    Zhai, C.; Vasisht, G.; Shao, M.; Lockhart, T.; Cady, E.; Oppenheimer, B.; Burruss, R.; Roberts, J.; Beichman, C.; Brenner, D.; Crepp, J.; Dekany, R.; Hillenbrand, L.; Hinkley, S.; Parry, I.; Pueyo, L.; Rice, E.; Roberts, L. C.; Sivaramakrishnan, A.; Soummer, R.; Tang, H.; Vescelus, F.; Wallace, K.; Zimmerman, N.
    P1640 high contrast imaging system on the Palomar 200 inch Telescope consists of an apodized-pupil Lyot coronagraph, the PALM-3000 adaptive optics (P3K-AO), and P1640 Calibrator (CAL). Science images are recorded by an integral field spectrograph covering J-H bands for detecting and characterizing stellar companions. With aberrations from atmosphere corrected by the P3K-AO, instrument performance is limited mainly by the quasi-static speckles due to noncommon path wavefront aberrations for the light to propagate to the P3K-AO wavefront sensor and to the coronagraph mask. The non-common path wavefront aberrations are sensed by CAL, which measures the post-coronagraph E-field using interferometry, and can...

  10. Precision near-infrared radial velocity instrumentation II: noncircular core fiber scrambler

    Plavchan, Peter P.; Bottom, M.; Gao, P.; Wallace, J. K.; Mennesson, B.; Ciardi, D.; Crawford, S.; Lin, S.; Beichman, C.; Brinkworth, C.; Johnson, J.; Davison, C.; White, R.; Anglada-Escudé, G.; von Braun, K.; Vasisht, G.; Prato, L.; Kane, S.; Tanner, A.; Walp, B.; Mills, S.
    We have built and commissioned a prototype agitated non-circular core ber scrambler for precision spectroscopic radial velocity measurements in the near-infrared H band. We have collected the rst on-sky performance and modal noise tests of these novel bers in the near-infrared at H and K bands using the CSHELL spectrograph at the NASA InfraRed Telescope Facility (IRTF). We discuss the design behind our novel reverse injection of a red laser for co-alignment of star-light with the ber tip via a corneWe have built and commissioned a prototype agitated non-circular core fiber scrambler for precision spectroscopic radial velocity measurements in the...

  11. The Fomalhaut debris disk seen from every angle with interferometry

    Absil, O.; Mennesson, B.; Le Bouquin, J.-B.; Augereau, J.-C.; Millan-Gabet, R.; Colavita, M.; Hinz, P.; Liu, W.; Serabyn, G.
    In this paper, we present the results of three different studies of the Fomalhaut debris disk with infrared interferometry. First, VLTI/AMBER measurements are used to determine the position angle of the slightly oblate rapidly rotating photosphere by means of differential phase measurements across the Br-gamma photospheric line. This measurement allows us to confirm that the debris disk is located in the equatorial plane of its host star. Second, we use VLTI/VINCI to search for resolved near-infrared emission around the stellar photosphere, which would correspond to the presence of large amounts of hot dust grains located between the sublimation radius and...

  12. Recent progress at the Keck Interferometer

    Ragland, S.; Akeson, R.; Colavita, M.; Millan-Gabet, R.; Woillez, J.; Wizinowich, P.; Appleby, E.; Berkey, B.; Cooper, A.; Felizardo, C.; Herstein, J.; Hrynevych, M.; Medeiroes, D.; Morrison, D.; Panteleeva, T.; Pott, J.-U.; Smith, B.; Summers, K.; Tsubota, K.; Tyau, C.; Wetherell, E.
    The Keck Interferometer (KI) combines the two 10m diameter Keck telescopes providing milliarcsecond angular resolution. KI has unique observing capabilities such as sensitive K-band V2, L-band V2 and N-band nulling operations. The instrument status of the Keck Interferometer since the last SPIE meeting in 2008 is summarized. We discuss the performance of new visibility observing capabilities including L-band and self-phase referencing modes. A simultaneous dual-beam-combiner mode in the K and L-band has been demonstrated, nearly doubling operational efficiency for bright targets. Operational improvements including simplified reliable operations with reduced personnel resources are highlighted. We conclude with a brief review of...

  13. The LBTI hunt for observable signatures of terrestrial systems (HOSTS) survey: a key NASA science program on the road to exoplanet imaging missions

    Danchi, W.; Bailey, V.; Bryden, G.; Defrère, D.; Haniff, C.; Hinz, P.; Kennedy, G.; Mennesson, B.; Millan-Gabet, R.; Rieke, G.; Roberge, A.; Serabyn, E.; Skemer, A.; Stapelfeldt, K.; Weinberger, A.; Wyatt, M.
    The Hunt for Observable Signatures of Terrestrial planetary Systems (HOSTS) program on the Large Binocular Telescope Interferometer (LBTI) will survey nearby stars for faint exozodiacal dust (exozodi). This warm circumstellar dust, analogous to the interplanetary dust found in the vicinity of the Earth in our own system, is produced in comet breakups and asteroid collisions. Emission and/or scattered light from the exozodi will be the major source of astrophysical noise for a future space telescope aimed at direct imaging and spectroscopy of terrestrial planets (exo- Earths) around nearby stars. About 20% of nearby field stars have cold dust coming from...

  14. UKIRT under new management: status and plans

    Hodapp, K. W.; Kerr, T.; Varricatt, W.; McLaren, R.; Lonborg, D.; Hall, D. N. B.; Jacobson, S.; Bruursema, J.; Dahm, S.; Dorland, B. N.; Munn, J. A.; Vrba, F. J.; Dempsey, J.; Shvartzvald, Y.; Bryden, G.; Gaudi, B. S.; Beichman, C.; Calchi Novati, S.; Henderson, C. B.; Jacklin, S.; Stassun, K.; Penny, M. T.; Irwin, Mike; Lawrence, Andy
    The United Kingdom Infrared Telescope (UKIRT) observatory has been transferred to the ownership of the University of Hawaii (UH) and is now being managed by UH. We have established partnerships with several organizations to utilize the UKIRT for science projects and to support its operation. Our main partners are the U.S. Naval Observatory (USNO), the East Asian Observatory (EAO), and the UKIRT microlensing team (JPL/IPAC/OSU/Vanderbilt). The USNO is working on deep northern hemisphere surveys in the H and K bands and the UKIRT microlensing team is running a monitoring campaign of the Galactic bulge. EAO, UH, and USNO have individual...

  15. The Highly Polarized Dusty Emission Core of Cygnus A

    Lopez-Rodriguez, Enrique; Antonucci, Robert; Chary, Ranga-Ram; Kishimoto, Makoto
    We report the detection of linearly polarized emission at 53 and 89 μm from the radio-loud active galactic nucleus (AGN) Cygnus A using High-resolution Airborne Wideband Camera-plus (HAWC+) on board the Stratospheric Observatory For Infrared Astronomy (SOFIA). We measure a highly polarized core of 11 ± 3% and 9 ± 2% with a position angle (PA) of polarization of 43° ± 8° and 39° ± 7° at 53 and 89 μm, respectively. We find (1) a synchrotron-dominated core with a flat spectrum (+0.21 ± 0.05) and a turnover at 543 ± 120 μm, which implies synchrotron emission is insignificant in...

  16. Science at mid-infrared wavelengths with large telescopes

    Telesco, C. M.; Ciardi, D.; Packham, C.
    For background-limited observations such as those at mid-infrared wavelengths, an increase in telescope aperture not only improves the angular resolution (as it does at all wavelengths) but also leads to very large increases in sensitivity because of the reduced background within the diffraction-limited point spread function. In this presentation we look at the magnitude of that increase for several different operational modes of mid-infrared instrumentation, and we consider some of the implications for science on the current generation of 8-10 meter telescopes.

  17. The Far Infrared Spectroscopic Explorer (FIRSPEX): probing the lifecycle of the ISM in the universe

    Rigopoulou, D.; Caldwell, M.; Ellison, B.; Pearson, C.; Caux, E.; Cooray, A.; Gallego, J. D.; Gerin, M.; Goicoechea, J. R.; Goldsmith, P.; Kramer, C.; Lis, D. C.; Molinari, S.; Ossenkopf-Okada, V.; Savini, G.; Tan, B. K.; Tielens, A.; Viti, S.; Wiedner, M.; Yassin, G.
    The Far Infrared Spectroscopic Explorer (FIRSPEX) is a novel European-led astronomy mission concept developed to enable large area ultra high spectroscopic resolution surveys in the THz regime. FIRSPEX opens up a relatively unexplored spectral and spatial parameter space that will produce an enormously significant scientific legacy by focusing on the properties of the multi-phase ISM, the assembly of molecular clouds in our Galaxy and the onset of star formation; topics which are fundamental to our understanding of galaxy evolution. The mission uses a heterodyne instrument and a ~1.2 m primary antenna to scan large areas of the sky in a...

  18. Enabling the direct detection of earth-sized exoplanets with the LBTI HOSTS project: a progress report

    Danchi, W.; Bailey, V.; Bryden, G.; Defrère, D.; Ertel, S.; Haniff, C.; Hinz, P.; Kennedy, G.; Mennesson, B.; Millan-Gabet, R.; Rieke, G.; Roberge, A.; Serabyn, E.; Skemer, A.; Stapelfeldt, K.; Weinberger, A.; Wyatt, M.; Vaz, A.
    NASA has funded a project called the Hunt for Observable Signatures of Terrestrial Systems (HOSTS) to survey nearby solar type stars to determine the amount of warm zodiacal dust in their habitable zones. The goal is not only to determine the luminosity distribution function but also to know which individual stars have the least amount of zodiacal dust. It is important to have this information for future missions that directly image exoplanets as this dust is the main source of astrophysical noise for them. The HOSTS project utilizes the Large Binocular Telescope Interferometer (LBTI), which consists of two 8.4-m apertures...

  19. Major outcomes of an authentic astronomy research experience professional development program: An analysis of 8 years of data from a teacher research program

    Rebull, L. M.; French, D. A.; Laurence, W.; Roberts, T.; Fitzgerald, M. T.; Gorjian, V.; Squires, G. K.
    The NASA/IPAC Teacher Archive Research Program (NITARP) provides a year-long authentic astronomy research project by partnering a research astronomer with small groups of educators. NITARP has worked with a total of 103 educators since 2005. In this paper, surveys are explored that were obtained from 74 different educators, at up to four waypoints during the course of 13 months, from the class of 2010 through the class of 2017; those surveys reveal how educator participants describe the major changes and outcomes in themselves fostered by NITARP. Three-quarters of the educators self-report some or major changes in their understanding of the...

  20. Degradation analysis in the estimation of photometric redshifts from non-representative training sets

    Rivera, J. D.; Moraes, B.; Merson, A. I.; Jouvel, S.; Abdalla, F. B.; Abdalla, M. C. B.
    We perform an analysis of photometric redshifts estimated by using a non-representative training sets in magnitude space. We use the ANNz2 and GPz algorithms to estimate the photometric redshift both in simulations and in real data from the Sloan Digital Sky Survey (DR12). We show that for the representative case, the results obtained by using both algorithms have the same quality, using either magnitudes or colours as input. In order to reduce the errors when estimating the redshifts with a non-representative training set, we perform the training in colour space. We estimate the quality of our results by using a...

Aviso de cookies: Usamos cookies propias y de terceros para mejorar nuestros servicios, para análisis estadístico y para mostrarle publicidad. Si continua navegando consideramos que acepta su uso en los términos establecidos en la Política de cookies.