Now showing items 1-20 of 301

    • 2 mm GISMO Observations of the Galactic Center. I. Dust Emission 

      Arendt, Richard G; Staguhn, Johannes; Dwek, Eli; Morris, Mark R; Yusef-Zadeh, Farhad; Benford, Dominic J; Kovacs, Attila; Gonzalez-Quiles, Junellie (The American Astronomical Society, 2019-11-01)
      The Central Molecular Zone (CMZ), covering the inner ∼ 1 ◦ of the Galactic plane has been mapped at 2 mm using the GISMO bolometric camera on the 30 m IRAM telescope. The 2100 resolution maps show abundant emission from ...
    • 2 mm GISMO Observations of the Galactic Center. II. A Nonthermal Filament in the Radio Arc and Compact Sources 

      Staguhn, Johannes; Arendt, Richard G; Dwek, Eli; Morris, Mark R; Yusef-Zadeh, Farhad; Benford, Dominic J; Kovacs, Attila; Gonzalez-Quiles, Junellie (The American Astronomical Society, 2019-11-01)
      We have used the Goddard IRAM 2-Millimeter Observer (GISMO) with the 30 m IRAM telescope to carry out a 2 mm survey of the Galaxy’s central molecular zone (CMZ). These observations detect thermal emission from cold ISM ...
    • 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)
    • 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-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 ...
    • 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 ...
    • Apparent superluminal core expansion and limb brightening in the candidate neutrino blazar TXS 0506+056 

      Ros, E.; Kadler, M.; Perucho, M.; Boccardi, B.; Cao, H.-M.; Giroletti, M.; Krauß, F.; Ojha, R. (2019-12-23)
      IceCube has reported a very-high-energy neutrino (IceCube-170922A) in a region containing the blazar TXS 0506+056. Correlated {\gamma}-ray activity has led to the first high-probability association of a high-energy neutrino ...
    • 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 ...
    • ATCA Observations of the New Gamma-ray Source PKS 1824-582 

      Edwards, Philip G.; Stevens, Jamie; Ojha, Roopesh (2014-04-17)
    • CALET upper limits on GeV-energy gamma-ray burst emission 

      Cannady, Nicholas (2019-07-24)
      The CALorimetric Electron Telescope (CALET) was deployed on the International Space Station in October 2015 and has accumulated over three years of continuous data to date. The calorimeter (CAL) is sensitive to gamma rays ...
    • Calorimetric neutrino expectations from bright blazar flares 

      Kreter, Michael; Kadler, Matthias; Krauß, Felicia; Buson, Sara; Ojha, Roopesh; Mannheim, Karl; Wilms, Jörn; Böttcher, Markus; Fermi/LAT Collaboration (Proceedings of Science, 2019-07-24)
      Blazar jets are extreme environments, in which relativistic proton interactions with an ultraviolet photon field could give rise to photopion production. High-confidence associations of individual high-energy neutrinos ...
    • Cassini Composite Infrared Spectrometer (CIRS) Observations of Titan 2004–2017 

      Nixon, Conor A.; Ansty, Todd M.; Lombardo, Nicholas A.; Bjoraker, Gordon L.; Achterberg, Richard K.; Annex, Andrew M.; Rice, Malena; Romani, Paul N.; Jennings, Donald E.; Samuelson, Robert E.; Anderson, Carrie M.; Coustenis, Athena; Bezard, Bruno; Vinatier, Sandrine; Lellouch, Emmanuel; Courtin, Regis; Teanby, Nicholas A.; Cottini, Valeria; Flasar, F. Michael (The American Astronomical Society, 2019-09-11)
      From 2004 to 2017, the Cassini spacecraft orbited Saturn, completing 127 close flybys of its largest moon, Titan. Cassini’s Composite Infrared Spectrometer (CIRS), one of 12 instruments carried on board, profiled Titan in ...
    • Characterization of long baseline calibrators at 2.3 GHz 

      Hungwe, F.; Ojha, R.; Booth, R. S.; Bietenholz, M. F.; Collioud, A.; Charlot, P.; Boboltz, D.; Fey, A. L. (Oxford University Press, 2011-12-08)
      We present a detailed multi-epoch analysis of 31 potential Southern hemisphere radio calibrators that were originally observed as part of a programme to maintain the International Celestial Reference Frame. At radio ...
    • Coincidence of a high-fluence blazar outburst with a PeV-energy neutrino event 

      Ojha, Roopesh; et al. (Nature, 2016-04-18)
      The astrophysical sources of the extraterrestrial, very high-energy neutrinos detected by the IceCube collaboration remain to be identified. Gamma-ray (γ-ray) blazars have been predicted to yield a cumulative neutrino ...