A5032880655- Astronomical Observations and Instrumentation
- Calibration and Measurement Techniques
- Astrophysical Phenomena and Observations
- Astronomy and Astrophysical Research
- Advanced X-ray Imaging Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Adaptive optics and wavefront sensing
- Catalytic Processes in Materials Science
- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Advanced Chemical Physics Studies
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Molecular Junctions and Nanostructures
- Scientific Measurement and Uncertainty Evaluation
- Solar and Space Plasma Dynamics
- Electrocatalysts for Energy Conversion
- Advanced Measurement and Metrology Techniques
- Sensor Technology and Measurement Systems
- Industrial Gas Emission Control
- Catalysis and Oxidation Reactions
- Spectroscopy Techniques in Biomedical and Chemical Research
- Optical Systems and Laser Technology
- Particle Accelerators and Free-Electron Lasers
- Astro and Planetary Science
Smithsonian Astrophysical Observatory
2025
Center for Astrophysics Harvard & Smithsonian
2020-2024
Los Alamos National Laboratory
2021
At Bristol
2015-2018
Harvard University Press
2016
Massachusetts Institute of Technology
2000-2013
Kavli Institute for Particle Astrophysics and Cosmology
2006-2012
Vassar College
2001-2011
The University of Texas at Austin
1996-1999
Technion – Israel Institute of Technology
1997
The Sloan Digital Sky Survey (SDSS) will provide the data to support detailed investigations of distribution luminous and nonluminous matter in universe: a photometrically astrometrically calibrated digital imaging survey π sr above about Galactic latitude 30° five broad optical bands depth g' ∼ 23 mag, spectroscopic approximately 106 brightest galaxies 105 quasars found photometric object catalog produced by survey. This paper summarizes observational parameters products SDSS serves as an...
The Sloan Digital Sky Survey (SDSS) is an imaging and spectroscopic survey that will eventually cover approximately one-quarter of the celestial sphere collect spectra ≈106 galaxies, 100,000 quasars, 30,000 stars, serendipity targets. In 2001 June, SDSS released to general astronomical community its early data release, roughly 462 deg2 including almost 14 million detected objects 54,008 follow-up spectra. were collected in drift-scan mode five bandpasses (u, g, r, i, z); our 95% completeness...
The CIAO (<i>Chandra</i> Interactive Analysis of Observations) software package was first released in 1999 following the launch <i>Chandra</i> X-ray Observatory and is used by astronomers across world to analyze data as well from other telescopes. From earliest design discussions, planned a general-purpose scientific analysis system optimized for astronomy, consists mainly command line tools (allowing easy pipelining scripting) with parameter-based interface layered on flexible manipulation...
The Chandra Source Catalog (CSC) is a general purpose virtual X-ray astrophysics facility that provides access to carefully selected set of generally useful quantities for individual sources, and designed satisfy the needs broad-based group scientists, including those who may be less familiar with astronomical data analysis in regime. first release CSC includes information about 94,676 distinct sources detected subset public ACIS imaging observations from roughly eight years mission. This...
Most supermassive black holes (SMBHs) are accreting at very low levels and difficult to distinguish from the galaxy centers where they reside. Our own Galaxy's SMBH provides a uniquely instructive exception, we present close-up view of its quiescent X-ray emission based on 3 mega-second Chandra observations. Although is elongated aligns well with surrounding disk massive stars, can rule out concentration low-mass coronally active stars as origin lack predicted Fe Kalpha emission. The...
The problem of event pileup in single-photon-counting CCD cameras (e.g., the X-ray regime) is discussed, and a solution to proposed. resulting equation includes effects grade migration presents itself as nonlinear modification standard integral used by forward-folding spectral-fitting programs. effectiveness model demonstrated its application moderately piled zeroth-order data obtained Chandra X-Ray Observatory for quasar S5 0836+7104.
Details of the design, fabrication, ground and flight calibration High Energy Transmission Grating, HETG, on Chandra X-ray Observatory are presented after five years experience. Specifics include theory phased transmission gratings as applied to Rowland design spectrometer, details grating fabrication techniques, results testing HETG. For nearly six HETG has operated essentially designed, although it some subtle effects.
MARX is a portable ray-trace program that was originally developed to simulate event data from the trans- mission grating spectrometers on-board Chandra X-ray Observatory (CXO). has since evolved include detailed models of all CXO science instruments and been further modified serve as an simulator for future observatory design concepts. We first review number applications demonstrate roles such could play throughout life mission, including its calibration, production input products...
We present photometric and spectroscopic observations of 15 high-redshift quasars (z > 3.6) discovered from ∼140 deg2 five-color (u', g', r', i', z') imaging data taken by the Sloan Digital Sky Survey (SDSS) during its commissioning phase. The are selected their distinctive colors in SDSS multicolor space. Four have redshifts higher than 4.6 = 4.63, 4.75, 4.90, 5.00, latter being highest redshift quasar yet known). In addition, two previously known z 4 objects were recovered data. all i* <...
We used the Spitzer Space Telescope's Infrared Spectrograph to map nearly entire extent of Cassiopeia A between 5-40 micron. Using infrared and Chandra X-ray Doppler velocity measurements, along with locations optical ejecta beyond forward shock, we constructed a 3-D model remnant. The structure Cas can be characterized into spherical component, tilted thick disk, multiple jets/pistons fast-moving knots all populating disk plane. Bright Ring in identifies intersection plane/pistons roughly...
Using Suzaku and the Rossi X-ray Timing Explorer, we have conducted a series of four simultaneous observations galactic black hole candidate Cyg X-1 in what were historically faint spectrally hard low states. Additionally, all these occurred near superior conjunction with our line sight to source passing through dense phases focused wind from mass donating secondary. One was also by Chandra-High Energy Transmission Grating. These latter spectra are crucial for revealing ionized absorption...
The Chandra Transmission Grating Data Archive and Catalog (TGCat) provides easy access to analysis-ready products, specifically, high-resolution X-ray count spectra their corresponding calibrations. web interface makes it find observations of a particular object, type or observation; quickly assess the quality potential usefulness from pre-computed summary plots; customize view with an interactive plotter, optionally combining over multiple orders observations. responses can be downloaded as...
Abstract This Algorithm Theoretical Basis Document (ATBD) describes the retrieval algorithm and sensitivities of Version 3 cloud product derived from spectra collected by Tropospheric Emissions: Monitoring POllution (TEMPO) instrument. The is primarily produced for supporting retrievals TEMPO trace gases that are important understanding atmospheric chemistry monitoring air pollution. adapted NASA's Ozone Instrument (OMI) oxygen collision complex (O 2 ‐O ) algorithm. generates effective...
High translational energy adsorption of oxygen on the (111) surface platinum was examined with electron loss spectroscopy (EELS) and molecular beam techniques. EEL spectra indicate that over an incident range 0.2–1.37 eV a Pt(111) held at 77 K, adsorbs in associative chemisorbed state—yielding to dissociated state only after sufficient substrate heating. Simple direct dissociation appears negligible for all kinetic energies studied. At near-zero coverages, exclusive population peroxolike...
We present the status of Tropospheric Emissions: Monitoring Pollution (TEMPO) nitrogen dioxide (NO2) and formaldehyde (HCHO) retrievals one year after their public release. After multiple version updates, TEMPO Level 2 NO2 HCHO products have undergone significant enhancements to improve performance accuracy slant column retrievals, air mass factor calculations post-processing corrections. Upcoming 4 will include improved destriping for background illustrate both evaluating fitting...
Thermodynamically, aqueous polysulfide solutions are unstable, and sulfur, dissolved as species, Sx2-, x = 2−5, will decompose to thiosulfate, S2O32- in accord with the net consumption of sulfur: Sdissolved + OH- → 1/4S2O32− 1/2HS- 1/4H2O. The distribution measured modeled rate decomposition, investigated for a wide range solution compositions from 25 85 °C. observed decomposition sulfur concentration, CS, is consistent an activation energy 104(±5) kJ mol-1 following loss: −dCS/dt...
Adsorption intermediates of oxygen on a platinum (111) surface were examined with electron energy-loss spectroscopy (EELS) and molecular beams. Low incident kinetic energies promote initial adsorption into both superoxolike $(870\mathrm{cm}{}^{\ensuremath{-}1})$ peroxolike $(690\mathrm{cm}{}^{\ensuremath{-}1})$ species at 77 K. High energies, however, exclusively populate the more strongly bound species, suggesting close correlation between energy reaction coordinate for adsorption. This...
The initial dissociative chemisorption probability, S0, of O2 on Ir(111) has been investigated with molecular beam techniques and electron energy loss spectroscopy (EELS). adsorption process the clean surface occurs by distinct dynamical mechanisms. At incident kinetic energies, Ei, 0.1 eV below, probability decreases increasing energy, indicating dominance a trapping-mediated mechanism. A decrease in value S0 temperature, Ts, is also characteristic this regime. This temperature dependence...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanisms of Initial Dissociative Chemisorption Oxygen on Transition-Metal SurfacesPeter D. Nolan, M. Clay Wheeler, John E. Davis, and C. Buddie MullinsView Author Information Department Chemical Engineering, The University Texas at Austin, 78712-1062 Cite this: Acc. Chem. Res. 1998, 31, 12, 798–804Publication Date (Web):September 3, 1998Publication History Received22 November 1996Published online3 September 1998Published inissue 1 December...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolubility of Ethylene in Water.J. E. Davis and J. McKettaCite this: Chem. Eng. Data 1960, 5, 3, 374–375Publication Date (Print):July 1, 1960Publication History Published online1 May 2002Published inissue 1 July 1960https://pubs.acs.org/doi/10.1021/je60007a039https://doi.org/10.1021/je60007a039research-articleACS PublicationsRequest reuse permissionsArticle Views856Altmetric-Citations22LEARN ABOUT THESE METRICSArticle Views are the...
The interaction of nitric oxide (NO) with an Ir(111) surface has been studied supersonic molecular beam techniques and electron energy loss spectroscopy. Initial adsorption probability S0, measurements as a function incident kinetic Ei, temperature Ts, angle incidence θi reveal that separate mechanisms govern at low high energy. This distinction is reflected in the initial where decrease value S0 increasing Ts (between 77 300 K) observed (Ei&lt;0.45 eV), but no dependence detected this...
SMART-X is a mission concept for 2.3 m<sup>2</sup> effective area, 0.5" angular resolution X-ray telescope, with 5' FOV, 1" pixel size microcalorimeter, 22' FOV imager, and high-throughput gratings.