Now showing items 1-20 of 358

    • A 1D fluid model of the Centaurus A jet 

      Wykes, Sarka; Snios, Bradford T.; Nulsen, Paul E. J.; Kraft, Ralph P.; Birkinshaw, Mark; Hardcastle, Martin J.; Worrall, Diana M.; McDonald, Iain; Rejkuba, Marina; Jones, Thomas W.; Stark, David J.; Forman, William R.; Meyer, Eileen T.; Jones, Christine (2018-09-27)
      We implement a steady, one-dimensional flow model for the X-ray jet of Centaurus A in which entrainment of stellar mass loss is the primary cause of dissipation. Using over 260 ks of new and archival Chandra/ACIS data, we ...
    • A 4‐year zonal climatology of lower tropospheric CO₂ derived from ocean‐only Atmospheric Infrared Sounder observations 

      Strow, L. Larrabee; Hannon, Scott E. (American Geophysical Union, 2008-09-20)
      A 4‐year zonally averaged climatology of atmospheric CO₂, ocean only, between ±60° latitude has been derived from the Atmospheric Infrared Sounder (AIRS) radiances. Using only very clear fields of view, the CO₂ profile in ...
    • The Accretion History of AGN: A Newly Defined Population of Cold Quasars 

      Kirkpatrick, Allison; Urry, C. Megan; Brewster, Jason; Cooke, Kevin C.; Estrada, Michael; Glikman, Eilat; Hamblin, Kurt; Ananna, Tonima Tasnim; Carlile, Casey; Coleman, Brandon; Johnson, Jordan; Kartaltepe, Jeyhan S.; LaMassa, Stephanie M.; Marchesi, Stefano; Powell, Meredith; Sanders, Dave; Treister, Ezequiel; Turner, Tracey Jane (2019-08-15)
      Quasars are the most luminous of active galactic nuclei (AGN), and are perhaps responsible for quenching star formation in their hosts. The Stripe 82X catalog covers 31.3 deg² of the Stripe 82 field, of which the 15.6 deg² ...
    • Accurate Astrometry of 22 Southern Hemisphere Radio Sources 

      Fey, Alan L.; Ojha, Roopesh; Jauncey, David L.; Johnston, Kenneth J.; Reynolds, John E.; Lovell, James E. J.; Tzioumis, Anastasios K.; Quick, Jonathan F. H.; Nicolson, George D.; Ellingsen, Simon P.; McCulloch, Peter M.; Koyama, Yasuhiro (IOP, 2003-12-03)
      Milliarcsecond-accurate radio positions for 22 southern hemisphere extragalactic sources are reported. These positions are derived from Mark III very long baseline interferometry observations made between 2003 February and ...
    • AGN TXS 1923+123 

      Carpenter, Bryce; Ojha, Roopesh (The Astronomer's Telegram, 2016-01-01)
    • AIRS L1c Frequency Calibration 

      UMBC Atmospheric Spectroscopy Lab (ASL) (2019-11-03)
      This document summarizes the observed frequency drifts in the AIRS L1b radiances and then describes how they are corrected in the AIRS L1c product that should be available at the NASA Goddard DISC in early 2010. The ...
    • AIRS version 6.6 and version 7 level-1C products 

      Manning, Evan M.; Strow, L. Larrabee; Aumann, Hartmut H. (SPIE, 2019-09-09)
      The Atmospheric Infrared Sounder (AIRS) introduces new Level-1C (L1C) products. AIRS Version 6.6 L1C processing addresses data quality and sampling issues as well as spectral drift, making a clean, easy to use product. ...
    • THE ALGOL TRIPLE SYSTEM SPATIALLY RESOLVED AT OPTICAL WAVELENGTHS 

      Zavala, R. T.; Hummel, C. A.; Boboltz, D. A.; Ojha, R.; Shaffer, D. B.; Tycner, C.; Richards, M. T.; Hutter, D. J. (IOP, 2010-04-30)
      Interacting binaries typically have separations in the milliarcsecond regime, and hence it has been challenging to resolve them at any wavelength. However, recent advances in optical interferometry have improved our ability ...
    • ALL-OPTICAL NONLINEAR ACTIVATION FUNCTION FOR PHOTONIC NEURAL NETWORKS 

      Miscuglio, Mario; Mehrabian, Armin; Hu, Zibo; Azzam, Shaimaa I.; George, Jonathan; Kildishev, Alexander V.; Pelton, Matthew; Sorger, Volker J. (Optical Society of America, 2018)
      With the recent successes of neural networks (NN) to perform machine-learning tasks, photonic-based NN designs may enable high throughput and low power neuromorphic compute paradigms since they bypass the parasitic charging ...
    • All-sky Medium Energy Gamma-ray Observatory: Exploring the Extreme Multimessenger Universe 

      McEnery, Julie E.; Ojha, R.; Georganopoulos, Markos; Meyer, Eileen (2019-07-10)
      The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a probe class mission concept that will provide essential contributions to multimessenger astrophysics in the late 2020s and beyond. AMEGO combines high sensitivity ...
    • An Analysis of NCEP Tropical Cyclone Vitals and Potential Effects on Forecasting Models 

      Trahan, Sam; Sparling, Lynn (American Meteorological Society, 2012-06-15)
      This study analyzes the Tropical Cyclone Vitals Database (TCVitals), which contains cyclone location, intensity, and structure information, generated in real time by forecasters. These data are used to initialize cyclones ...
    • Analytically parameterized solutions for robust quantum control using smooth pulses 

      Gungordu, Utkan; Kestner, J. P. (2019-06)
      Achieving high-fidelity control of quantum systems is essential for realization of a practical quantum computer. Composite pulse sequences which suppress different types of errors can be nested to suppress a wide variety ...
    • Angular Broadening of Intraday Variable AGNs. II. Interstellar and Intergalactic Scattering 

      Lazio, T. Joseph W.; Ojha, Roopesh; Fey, Alan L.; Kedziora-Chudczer, Lucyna; Cordes, James M.; Jauncey, David L.; Lovell, James E. J. (IOP, 2008-01-01)
      We analyze a sample of 58 multiwavelength, Very Long Baseline Array observations of active galactic nuclei (AGNs) to determine their scattering properties. Approximately 75% of the sample consists of AGNs that ...
    • The Antarctic Submillimeter Telescope and Remote Observatory (AST/RO) 

      Stark, Antony A.; Bally, John; Balm, Simon P.; Bania, T. M.; Bolatto, Alberto D.; Chamberlin, Richard A.; Engargiola, Gregory; Huang, Maohai; Ingalls, James G.; Jacobs, Karl; Jackson, James M.; Kooi, Jacob W.; Lane, Adair P.; Lo, K.-Y.; Marks, Rodney D.; Martin, Christopher L.; Mumma, Dennis; Ojha, Roopesh; Schieder, Rudolf; Staguhn, Johannes; Stutzki, Juergen; Walker, Christopher K.; Wilson, Robert W.; Wright, Gregory A.; Zhang, Xiaolei; Zimmermann, Peter; Zimmermann, Ruediger (IOP, 2000-12-15)
      AST/RO, a 1.7 m diameter telescope for astronomy and aeronomy studies at wavelengths between 200 and 2000 microns, was installed at the South Pole during the 1994-1995 Austral summer. The telescope operates continuously ...
    • ANTARES constrains a blazar origin of two IceCube PeV neutrino events 

      Ojha, R. (EDP sciences, 2015-03-30)
      The source(s) of the neutrino excess reported by the IceCube Collaboration is unknown. The TANAMI Collaboration recently reported on the multiwavelength emission of six bright, variable blazars which are positionally ...
    • Assessing Water Budget Sensitivity to Precipitation Forcing Errors in Potomac River Basin Using the VIC Hydrologic Model CyberTraining: Big Data + High-Performance Computing + Atmospheric Sciences 

      Majumder, Reetam; Walid, Redwan; Zheng, Jianyu (2019)
      The Potomac River Basin is a watershed located on the East Coast of the USA across West Virginia, Virginia, Pennsylvania, Maryland, and the District of Columbia. Inter-annual variations in precipitation makes it challenging ...
    • An assessment of the tropical humidity‐temperature covariance using AIRS 

      Gambacorta, A.; Barnet, C.; Soden, B.; Strow, L. (American Geophysical Union, 2008-05-29)
      We investigate the horizontal and vertical structure of the covariance between water vapor and temperature in the tropical troposphere, using satellite measurements from the Atmospheric InfraRed Sounder (AIRS). Our analysis ...
    • AST/RO Observations of Atomic Carbon near the Galactic Center 

      Ojha, Roopesh; Stark, Antony A.; Hsieh, Henry H.; Lane, Adair P.; Chamberlin, Richard A.; Bania, Thomas M.; Bolatto, Alberto D.; Jackson, James M.; Wright, Gregory A. (IOP, 2001-02-10)
      We present a coarsely sampled map of the region |l| ≤ 2°, |b| ≤ 0°1 in the 492 GHz (³P₁ → ³P₀) fine-structure transition of neutral carbon, observed with the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO). ...
    • Astrometry of 25 Southern Hemisphere Radio Sources from a VLBI Short-Baseline Survey 

      Fey, Alan L.; Ojha, Roopesh; Reynolds, John E.; Ellingsen, Simon P.; McCulloch, Peter M.; Jauncey, David L.; Johnston, Kenneth J. (IOP, 2004-11)
      Milliarcsecond-accurate radio positions for 25 southern hemisphere extragalactic sources are reported. These positions are derived from Mark III Very Long Baseline Interferometry observations made between 2003 September ...
    • ATCA monitoring of gamma-ray loud AGN 

      Stevens, J.; Edwards, P. G.; Ojha, R.; Kadler, M.; Hungwe, F.; Dutka, M.; Tingay, S.; Macquart, J. P.; Moin, A.; Lovell, J.; Blanchard, J. (2012-11-12)
      As a critical part of the Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry (TANAMI) program, in November 2007 the Australia Telescope Compact Array (ATCA) started monitoring the radio spectra of ...