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Article
Optimizing performance-per-watt on GPUs in high performance computing
The magnitude of the real-time digital signal processing challenge attached to large radio astronomical antenna arrays motivates use of high performance computing (HPC) systems. The need for high power efficie...
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Article
H_2O Megamasers: Accretion Disks, Jet Interaction, Outflows or Massive Star Formation?
The 25 years following the serendipitous discovery of megamasers have seen tremendous progress in the study of luminous extragalactic H2O emission. Single-dish monitoring and high-resolution interferometry have b...
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Chapter
H20 Megamasers: Accretion Disks, Jet Interaction, Outflows or Massive Star Formation?
The 25 years following the serendipitous discovery of megamasers have seen tremendous progress in the study of luminous extragalactic H20 emission. Single-dish monitoring and high-resolution interferometry have b...
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Article
The Sub-Pc Scale Accretion Disk of Ngc 4258
Water megamasers have been found to trace parsec/sub-parsec, circumnuclear accretion disks in several AGN (e.g., Circinus, NGC 1068 & NGC 4258). High-spatial (0.5 mas) and velocity resolution (0.2 km s−1) VLBA im...
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Chapter
The Sub-PC Scale Accretion Disk of NGC 4258
Water megamasers have been found to trace parsec/sub-parsec, circumnuclear accretion disks in several AGN (e.g., Circinus, NGC 1068 & NGC 4258). High-spatial (0.5 mas) and velocity resolution (0.2 km s−1) VLBA im...
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Chapter and Conference Paper
Probing the Magnetic Field at Sub-Parsec Radiiin the Accretion Disk of NGC 4258
We present an analysis of polarimetric observations of the water vapor masers in NGC 4258 obtained with the GBT at 22 GHz. We do not detect any circular polarization in the spectrum indicative of Zeeman-induce...
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Article
Observational evidence for massive black holes in the centers of active galaxies
Naturally occurring water vapor maser emission at 1.35 cm wavelength provides an accurate probe for the study of accretion disks around highly compact objects, thought to be black holes, in the centers of acti...
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Article
A geometric distance to the galaxy NGC4258 from orbital motions in a nuclear gas disk
The accurate measurement of extragalactic distances is a central challenge of modern astronomy, being required for any realistic description of the age, geometry and fate of the Universe. The measurement of re...
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Article
Coexisting conical bipolar and equatorial outflows from a high-mass protostar
The BN/KL region in the Orion molecular cloud1 is an archetype for the study of the formation of stars much more massive than the Sun2. This region contains luminous young stars and protostars but, like most star...
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Article
VLBI Imaging of Water Maser Emission from a Nuclear Disk in NGC 1068
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Chapter and Conference Paper
Probing AGN with Water Masers
Observations of the angular distribution of the water masers in the nucleus of NGC4258 reveal the presence of a thin molecular disk in nearly perfect Keplerian orbit (Miyoshi et al., 1995; Moran et al., 1995). Ab...
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Article
Inner radii of dust shells and stellar diameters obtained by an infrared stellar interferometer at 11 micron wavelength
Visibility data and analyses are discussed for 16 late-type stars observed with the Infrared Spatial Interferometer (ISI) of the University of California, Berkeley.
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Article
The sio masers and dust shell of VX sgr
The circumstellar envelope of the late-type supergiant VX Sagittarii has been studied with VLBI observations of SiO maser emission (J = 1 → 0v = 1) and interferometric observations of mid-infrared dust emission.
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Chapter and Conference Paper
Inner Radii of Dust Shells and Stellar Diameters Obtained by an Infrared Stellar Interferometer at 11 Micron Wavelength
Visibility data and analyses are discussed for 16 late-type stars observed with the Infrared Spatial Interferometer (ISI) of the University of California, Berkeley.
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Chapter and Conference Paper
The SiO Masers and Dust Shell of VX Sgr
The circumstellar envelope of the late-type supergiant VX Sagittarii has been studied with VLBI observations of SiO maser emission (J = 1 → 0 υ = 1) and interferometric observations of mid-infrared dust emission.
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Chapter and Conference Paper
Latest Technical Developments at the Infrared Spatial Interferometer
Recent upgrades of the Infrared Spatial Interferometer are described. These provide improved sensitivity, precision and convenience of measurement. Analysis of phase fluctuations within the interferometer as w...
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Chapter and Conference Paper
Heterodyne Interferometry in the Infrared
The University of California Infrared Spatial Interferometer (ISI) for the 10 gm wavelength region is briefly described along with results obtained on prominent stars and on atmospheric phenomena. The system h...
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Chapter and Conference Paper
VLBI observations of the water vapor megamaser in IC10
We present VLBI synthesis observations of the water vapor megamaser in the south eastern region of IC10. We compare our spectrum with earlier single dish spectra and conclude that the maser is highly variable.
