A correlation between the spectral and timing properties of AGN (2009)
Papadakis, I. E., Sobolewska, M., Arevalo, P., Markowitz, A., McHardy, I. M., Miller, L., ...
We present the results from a combined study of the average X-ray spectral and timing properties of 14 nearby AGN. For 11 of the sources in the sample, we used all the available data from the RXTE...
On the efficiency of production of the Fe Kalpha emission line in neutral matter (2009)
Yaqoob, T., Murphy, K. D., Miller, L., Turner, T. J.
The absolute luminosity of the Fe Kalpha emission line from matter illuminated by X-rays in astrophysical sources is nontrivial to calculate except when the line-emitting medium is optically-thin to...
The absorption-dominated model for the X-ray spectra of type I active galaxies: MCG-6-30-15 (2009)
Miller, L., Turner, T. J., Reeves, J. N.
MCG-6-30-15 is the archetypal example of a type I active galaxy showing broad "red-wing" emission in its X-ray spectrum at energies below the 6.4 keV Fe K-alpha emission line and a continuum excess...
A Compton-thick Wind in the High Luminosity Quasar, PDS 456 (2009)
Reeves, J. N., O'Brien, P. T., Braito, V., Behar, E., Miller, L., Turner, T. J., ...
PDS 456 is a nearby (z=0.184), luminous (L_bol ~10^47 erg/s) type I quasar. A deep 190 ks Suzaku observation in February 2007 revealed the complex, broad band X-ray spectrum of PDS 456. The Suzaku...
Turner, T. J., Miller, L., Kraemer, S. B., Reeves, J. N., Pounds, K. A.
We present results from a 200 ks Suzaku observation of 1H 0419-577 taken during 2007 July. The source shows a strong excess of counts above 10 keV compared to the extrapolation of models based on...
X-ray Absorption and Reflection in Active Galactic Nuclei (2009)
X-ray spectroscopy offers an opportunity to study the complex mixture of emitting and absorbing components in the circumnuclear regions of active galactic nuclei, and to learn about the accretion...
Multi-dimensional modelling of X-ray spectra for AGN accretion-disk outflows (2008)
Sim, S. A., Long, K. S., Miller, L., Turner, T. J.
We use a multi-dimensional Monte Carlo code to compute X-ray spectra for a variety of active galactic nucleus (AGN) disk-wind outflow geometries. We focus on the formation of blue-shifted absorption...
An absorption origin for the X-ray spectral variability of MCG-6-30-15 (2008)
Miller, L., Turner, T. J., Reeves, J. N.
The Seyfert I galaxy MCG-6-30-15 shows one of the best examples of a broad "red wing" of emission in its X-ray spectrum at energies 2 < E < 6.4 keV, commonly interpreted as being caused by...
Fourier-resolved energy spectra of the Narrow Line Seyfert 1 Mkn 766 (2008)
Arevalo, P., McHardy, I. M., Markowitz, A., Papadakis, I. E., Turner, T. J., Miller, L., ...
We compute Fourier-resolved X-ray spectra of the Seyfert 1 Markarian 766 to study the shape of the variable components contributing to the 0.3-10 keV energy spectrum and their time-scale dependence....
Tracing a Disk Wind in NGC 3516 (2008)
Turner, T. J., Reeves, J. N., Kraemer, S. B., Miller, L.
X-ray spectra of AGN often contain signatures indicative of absorption in multiple layers of gas whose ionization-state and covering fraction may vary with time. It has been unclear to date how much...
Asca Observations Of The Ionized Gas In The Seyfert Galaxy Ngc 3783 (2007)
I. M. George, T. J. Turner, George Turner Mushotzky, K. Nandra, H. Netzer
We present the results from ASCA observations of NGC 3783 carried out during 1993 and 1996. Variability is observed both between the two epochs and within the individual observations, the latter due...
Deo, R. P., Crenshaw, D. M., Kraemer, S. B., Dietrich, M., Elitzur, M., Teplitz, H., ...
We present Spitzer Space Telescope mid-infrared spectra of 12 Seyfert 1.8 and 1.9 galaxies over the 5-38 um region. We compare the spectral characteristics of this sample to those of 58 Seyfert 1 and...
Low accretion rates at the AGN cosmic downsizing epoch (2007)
Babic, A., Miller, L., Jarvis, M. J., Turner, T. J., Alexander, D. M., Croom, S. M.
Context: X-ray surveys of Active Galactic Nuclei (AGN) indicate `cosmic downsizing', with the comoving number density of high-luminosity objects peaking at higher redshifts (z about 2) than...
The Variable X-ray Spectrum of Markarian 766 - II. Time-Resolved Spectroscopy (2007)
Turner, T. J., Miller, L., Reeves, J. N., Kraemer, S. B.
CONTEXT: The variable X-ray spectra of AGN systematically show steep power-law high states and hard-spectrum low states. The hard low state has previously been found to be a component with only weak...
Relativistic Iron K Emission and absorption in the Seyfert 1.9 galaxy MCG-5-23-16 (2007)
Braito, V., Reeves, J. N., Dewangan, G. C., George, I., Griffiths, R. E., Markowitz, A., ...
We present the results of the simultaneous deep XMM and Chandra observations of the bright Seyfert 1.9 galaxy MCG-5-23-16, which is thought to have one of the best known examples of a...
A Photoionization Model For The Soft X-Ray Spectrum Of NGC 4151 (2007)
Armentrout, B. K., Kraemer, S. B., Turner, T. J.
We present analysis of archival data from multiple XMM-Newton observations of the Seyfert 1 galaxy NGC 4151. Spectral data from the RGS instruments reveal several strong soft X-ray emission lines,...
An XMM-Newton view of the X-ray flat radio-quiet quasar PG 1416-129 (2007)
Porquet, D., Reeves, J. N., Markowitz, A., Turner, T. J., Miller, L., Nandra, K.
Low accretion rates at the AGN cosmic downsizing epoch. (2007)
Babic, A., Miller, L., Jarvis, M.J., Turner, T.J., Alexander, D.M., Croom, S.M.
An XMM-Newton view of the X-ray flat radio-quiet quasar PG 1416-129 (2006)
Porquet, D., Reeves, J. N., Markowitz, A., Turner, T. J., Miller, L., Nandra, K.
(abridged) The radio-quiet quasar PG1416-129 (z=0.129) exhibits atypical optical and X-ray properties. Between 1990 and 2000, in response to its optical continuum decrease, the ``classical'' broad...
The variable X-ray spectrum of Markarian 766 - I. Principal components analysis (2006)
Miller, L., Turner, T. J., Reeves, J. N., George, I. M., Kraemer, S. B., Wingert, B.
Aims: We analyse a long XMM-Newton spectrum of the narrow-line Seyfert 1 galaxy Mrk 766, using the marked spectral variability on timescales >20ks to separate components in the X-ray spectrum....
The Energy-dependent X-ray Timing Characteristics of the Narrow Line Seyfert 1 Mkn 766 (2006)
Markowitz, A., Papadakis, I. E., Arevalo, P., Turner, T. J., Miller, L., Reeves, J. N.
We present the energy-dependent power spectral density (PSD) and cross-spectral properties of Mkn 766, obtained from combining data obtained during an XMM-Newton observation spanning six revolutions...
An XMM-Newton survey of broad iron lines in AGN (2006)
Nandra, K., O'Neill, P. M., George, I. M., Reeves, J. N., Turner, T. J.
We report on the iron K-alpha line properties of a sample of Seyfert galaxies observed with the XMM-Newton EPIC pn instrument. Using a systematic and uniform analysis, we find that complexity at...
Kraemer, S. B., Crenshaw, D. M., Gabel, J. R., Kriss, G. A., Netzer, H., Peterson, B. M., ...
We present a detailed analysis of the intrinsic absorption in the Seyfert 1 galaxy NGC 4151 using UV spectra from the HST/STIS and FUSE, obtained 2002 May as part of a set of contemporaneous...
A Cloudy/Xspec Interface (2006)
Porter, R. L., Ferland, G. J., Kraemer, S. B., Armentrout, B. K., Arnaud, K. A., Turner, T. J.
We discuss new functionality of the spectral simulation code CLOUDY which allows the user to calculate grids with one or more initial parameters varied and formats the predicted spectra in the...
Variable iron-line emission near the black hole of Markarian 766 (2006)
Miller, L., Turner, T. J., Reeves, J. N., George, I. M., Porquet, D., Nandra, K., ...
We investigate the link between ionised Fe X-ray line emission and continuum emission in the bright nearby AGN, Mrk 766. A new long (433 ks) XMM-Newton observation is analysed, together with archival...
The iron emission line complex of MCG-5-23-16: the long XMM-Newton look (2006)
Braito, V., Reeves, J. N., Dewangan, G., George, I., Griffiths, R., Markowitz, A., ...
Variable iron-line emission near the black hole of Markarian 766 (2006)
Miller, L., Turner, T. J., Reeves, J. N., George, I. M., Porquet, D., Nandra, K., ...
The Highly Red-Shifted Fe Kα Line in ESO 113-G010 (2006)
Porquet, D., Reeves, J.N., Uttley, P., Turner, T.J.
Not Available
Collaborate to compete: a strategic weapon for SMEs (2006)
Bititci, U.*, Turner, T.J., Kearney, D.
This paper reports on the value of collaboration in helping SMEs identify more clearly their positions in their markets and to provide pointers to strategies that might lead to increased...
Collaborate to compete: a strategic weapon for SMEs (2006)
Bititci, U., Turner, T.J., Kearney, D.
This paper reports on the value of collaboration in helping SMEs identify more clearly their positions in their markets and to provide pointers to strategies that might lead to increased...
Using simulation modelling to predict value stream performance (2006)
Turner, T.J., Giles, D.A.L., Albores-Barajas, P.A., Mitchell, R.
Reeves, J.N., Pounds, Kenneth A., Uttley, P., Kraemer, S., Mushotzky, R., Yaqoob, T., ...
The definitive version of this paper, with enhancements, is available from http://www.journals.uchicago.edu/ApJ/journal/issues/ApJL/v633n2/19868/19868.html
Ionization structure of the warm wind in NGC 5548 (2005)
Steenbrugge, K. C., Kaastra, J. S., Crenshaw, D. M., Kraemer, S. B., Arav, N., George, I. M., ...
We present the results from our 140 ks XMM-Newton and 500 ks Chandra observation of NGC 5548. The velocity structure of the X-ray absorber is consistent with the velocity structure measured in the...
The Spectral Energy Distribution of the Seyfert galaxy Ton S180 (2005)
Turner, T. J., Romano, P., Kraemer, S. B., George, I. M., Yaqoob, T., Crenshaw, D. M., ...
We present spectral results from a multi-satellite, broad-band campaign on the Narrow-line Seyfert 1 galaxy Ton S180 performed at the end of 1999. We discuss the spectral-energy distribution of the...
Reeves, J. N., Pounds, K., Uttley, P., Kraemer, S., Mushotzky, R, Yaqoob, T., ...
We report the detection of redshifted iron K-alpha absorption lines in the Chandra LETG spectrum of the narrow-line quasar, PG 1211+143. The absorption lines are observed at 4.22 keV and 4.93 keV in...
Kraemer, S. B., George, I. M., Crenshaw, D. M., Gabel, J. R., Turner, T. J., Gull, T. R., ...
We present a detailed analysis of the intrinsic X-ray absorption in the Seyfert 1 galaxy NGC 4151 using Chandra/HETGS data obtained 2002 May, as part of a program which included simultaneous UV...
Gabel, J. R., Kraemer, S. B., Crenshaw, D. M., George, I. M., Brandt, W. N., Hamann, F. W., ...
We present results on the location, physical conditions, and geometry of the outflow in the Seyfert 1 galaxy NGC 3783 from a study of the variable intrinsic UV absorption. Based on 18 observations...
Evidence for Orbital Motion of Material Close to the Central Black Hole of Mrk 766 (2005)
Turner, T. J., Miller, L., George, I. M., Reeves, J. N.
Time-resolved X-ray spectroscopy has been obtained for the narrow line Seyfert galaxy Mrk766 from XMM-Newton observations. We present analysis in the energy-time plane of EPIC pn data in the 4-8 keV...
XMM-Newton Spectroscopy of the Starburst Dominated Ultra Luminous Infrared Galaxy NGC 6240 (2005)
Netzer, Hagai, Lemze, Doron, Kaspi, Shai, George, I. M., Turner, T. J., Lutz, D., ...
We present new XMM-Newton observation of the Ultra Luminous Infrared Galaxy (ULIRG) NGC 6240. We analyze the reflecting grating spectrometer (RGS) data, and data from the other instruments, and find...
Steenbrugge, K. C., Kaastra, J. S., Crenshaw, D. M., Kraemer, S. B., Arav, N., George, I. M., ...
We present the results from a 500 ks Chandra observation of the Seyfert 1 galaxy NGC 5548. We detect broadened emission lines of O VII and C VI in the spectra, similar to those observed in the...
XMM-Newton spectroscopy of the starburst-dominated ultraluminous infrared galaxy NGC 6240 (2005)
Netzer, Hagai, Lemze, Doron, Kaspi, Shai, George, I. M., Turner, T. J., Lutz, D., ...
Imlementation and impact of performance measures in two SMEs in Central Scotland (2005)
Turner, T.J., Bititci, U., Nudurupati, S.S.
This paper describes how performance measures were selected and then implemented in two small to medium size enterprises (SMEs) in Central Scotland. It then goes on to consider the impact of these...
Imlementation and impact of performance measures in two SMEs in Central Scotland (2005)
Turner, T.J., Bititci, U., Nudurupati, S.S.
This paper describes how performance measures were selected and then implemented in two small to medium size enterprises (SMEs) in Central Scotland. It then goes on to consider the impact of these...
Imlementation and impact of performance measures in two SMEs in Central Scotland (2005)
Turner, T.J., Bititci, U., Nudurupati, S.S.
This paper describes how performance measures were selected and then implemented in two small to medium size enterprises (SMEs) in Central Scotland. It then goes on to consider the impact of these...
Complex X-ray Absorption and the Fe Kalpha Profile in NGC 3516 (2004)
Turner, T. J., Kraemer, S. B., George, I. M., Reeves, J. N., Bottorff, M. C.
We present data from simultaneous Chandra, XMM-Newton and BeppoSAX observations of the Seyfert 1 galaxy NGC 3516, taken during 2001 April and Nov. We have investigated the nature of the very flat...
Reeves, J. N., Porquet, D., Turner, T. J.
We report on a short XMM-Newton observation of the radio-quiet Narrow Line Seyfert 1 PG 1402+261. The EPIC X-ray spectrum of PG 1402+261 shows a strong excess of counts between 6-9 keV in the rest...
Crenshaw, D. M., Kraemer, S. B., Gabel, J. R., Schmitt, H. R., Filippenko, A. V., Ho, L. C., ...
We present ultraviolet spectra of the dwarf Seyfert 1 nucleus of NGC 4395, obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) and the Hubble Space Telescope's Space Telescope Imaging...
The Properties and the Evolution of the Highly Ionized Gas in MR2251-178 (2004)
Kaspi, Shai, Netzer, Hagai, Chelouche, Doron, George, Ian M., Nandra, Kirpal, Turner, T. J.
(abridged) We present the first XMM-Newton observations of the radio-quiet quasar MR2251-178 obtained in 2000 and 2002. The EPIC-pn spectra show a power-law continuum with a slope of 1.6 at high...
Kaastra, J. S., Steenbrugge, K. C., Crenshaw, D. M., Kraemer, S. B., Arav, N., George, I. M., ...
The Seyfert 1 galaxy NGC 5548 was observed for a week by Chandra using both the HETGS and LETGS spectrometers. In this paper we study the time variability of the continuum radiation. During our...
The XMM-Newton iron line profile of NGC 3783 (2004)
Reeves, J.N., Nandra, K., George, I.M., Pounds, Kenneth A., Turner, T.J., Yaqoob, T.
The definitive version of this paper is that available at http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v602n2/58961/58961.html
Managing the value delivery process (2004)
Turner, T.J., Martinez, V., Bititci, U.
This paper introduces a reference model for the life cycle of a logical business unit (LBU). It goes on to explain how the model was deduced from empirical data generated during participation by the...
Implementing a web enabled performance measurement system (2004)
Turner, T.J., Bititci, U., Creighton, S., Nudurupati, S.S.
A Web-enabled-performance-measurement system was designed, implemented and used to improve the business performance of a company processing aluminum foil in central Scotland. The benefits of the...
Implementing a web enabled performance measurement system (2004)
Turner, T.J., Bititci, U., Creighton, S., Nudurupati, S.S.
A Web-enabled-performance-measurement system was designed, implemented and used to improve the business performance of a company processing aluminum foil in central Scotland. The benefits of the...
Managing the value delivery process (2004)
Turner, T.J., Martinez, V., Bititci, U.
This paper introduces a reference model for the life cycle of a logical business unit (LBU). It goes on to explain how the model was deduced from empirical data generated during participation by the...
Implementing a web enabled performance measurement system (2004)
Turner, T.J., Bititci, U., Creighton, S., Nudurupati, S.S.
A Web-enabled-performance-measurement system was designed, implemented and used to improve the business performance of a company processing aluminum foil in central Scotland. The benefits of the...
Managing the value delivery process (2004)
Turner, T.J., Martinez, V., Bititci, U.
This paper introduces a reference model for the life cycle of a logical business unit (LBU). It goes on to explain how the model was deduced from empirical data generated during participation by the...
The Properties and the Evolution of the Highly Ionized Gas in MR2251-178 (2003)
Kaspi, S., Netzer, H., Chelouche, D., George, I. M., Turner, T. J., Nandra, K.
We present the first XMM-Newton observations of the radio-quiet quasar MR2251-178. We model the X-ray spectrum with two power laws, one at high energies with a slope of \Gamma=1.6 and the other to...
Transient Relativistically-Shifted Lines as a Probe of Black Hole Systems (2003)
Turner, T. J., Kraemer, S. B., Reeves, J. N.
X-ray spectra of Seyfert galaxies have revealed a new type of X-ray spectral feature, one which appears to offer important new insight into the black hole system. XMM/Chandra revealed several narrow...
The XMM-Newton Iron Line Profile of NGC 3783 (2003)
Reeves, J. N, Nandra, K., George, I. M., Pounds, K. A., Turner, T. J., Yaqoob, T.
We report on observations of the iron K line in the nearby Seyfert 1 galaxy, NGC 3783, obtained in a long, 2 orbit (240 ks) XMM-Newton observation. The line profile obtained exhibits two strong...
A warm hot intergalactic medium towards 3C 120? (2003)
McKernan, B., Yaqoob, T., Mushotzky, R., George, I. M., Turner, T. J.
We observed the Seyfert I active galaxy/broad line radio galaxy 3C120 with the Chandra high energy transmission gratings and present an analysis of the soft X-ray spectrum. We identify the strongest...
Netzer, H., Kaspi, S., Behar, E., Brandt, W. N., Chelouche, D., George, I. M., ...
We present a detailed spectral analysis of the data obtained from NGC 3783 during the period 2000-2001 using Chandra. This analysis leads us to the following results. 1) NGC 3783 fluctuated in...
XMM-Newton Observation of Fe Kalpha emission from a BAL QSO: Mrk 231 (2003)
We present results from a 20 ksec XMM observation of Mrk 231. EPIC data reveal strong line emission due to Fe Ka, which has rarely been detected in this class. The line energy is consistent with an...
Yaqoob, T., George, I. M., Kallman, T. R., Padmanabhan, U., Weaver, K. A., Turner, T. J.
We report the detection of Fe XXV and Fe XXVI $K\alpha$ emission lines from a Chandra HETGS observation of the Seyfert~1 galaxy NGC 7314, made simultaneously with RXTE. The lines are redshifted (cz ~...
Gabel, J. R., Crenshaw, D. M., Kraemer, S. B., Brandt, W. N., George, I. M., Hamann, F. W., ...
We report an intrinsic absorber with decreasing outflow velocity in the Seyfert 1 galaxy NGC 3783. This is the first detection of a change in radial velocity in an outflow associated with a Seyfert...
Elemental Abundances in NGC 3516 (2003)
Turner, T. J., Kraemer, S. B., Mushotzky, R. F., George, I. M., Gabel, J. R.
We present RGS data from an XMM-Newton observation of the Seyfert 1 galaxy NGC 3516, taken while the continuum source was in an extreme low state. The spectrum shows numerous emission lines including...
Crenshaw, D. M., Kraemer, S. B., Gabel, J. R., Kaastra, J. S., Steenbrugge, K. C., Brinkman, A. C., ...
We present new UV spectra of the nucleus of the Seyfert 1 galaxy NGC 5548, which we obtained with the Space Telescope Imaging Spectrograph at high spectral resolution, in conjunction with...
McKernan, B., Yaqoob, T., George, I. M., Turner, T. J.
We observed the Seyfert 1 galaxy NGC 4593 with the Chandra high energy transmission gratings and present a detailed analysis of the soft X-ray spectrum. We measure strong absorption lines from...
The Ionized Gas and Nuclear Environment in NGC 3783 II. Averaged HST/STIS and FUSE Spectra (2002)
Gabel, Jack R., Crenshaw, D. Michael, Kraemer, Steven B., Brandt, W. N., George, Ian M., Hamann, Frederick W., ...
We present observations of the intrinsic absorption in the Seyfert 1 galaxy NGC 3783 obtained with the STIS/HST and FUSE. We have coadded multiple STIS and FUSE observations to obtain a high S/N...
SHEEP: The Search for the High Energy Extragalactic Population (2002)
Nandra, K., Georgantopoulos, I., Ptak, A., Turner, T. J.
We present the SHEEP survey for serendipitously-detected hard X-ray sources in ASCA GIS images. In a survey area of $\sim 40$ deg$^{2}$, 69 sources were detected in the 5-10 keV band to a limiting...
Yaqoob, T., McKernan, B., Kraemer, S. B., Crenshaw, M., Gable, J., George, I. M., ...
We observed the Seyfert 1 galaxy Mrk 509 simultaneously with Chandra/HETG, HST/STIS and RXTE. We measure strong absorption lines from He-like Ne and Mg, and from H-like N, O, and Ne. The lines are...
Kraemer, S. B., Crenshaw, D. M., Yaqoob, T., McKernan, B., Gabel, J. R., George, I. M., ...
We present observations of the UV absorption lines in the luminous Seyfert 1 galaxy Mrk 509, obtained with the medium resolution (lambda/Delta-lambda ~ 40,000) echelle gratings of the Space Telescope...
Turner, T.J., Mendibil, K., Mendibil, K., Bititci, U.S., Daisley, P., Breen, T. H. J.
This paper explains how the improvement of a key business process in a manufacturing company can be interpreted in terms of reliability engineering concepts. A case study is presented to illustrate...
Turner, T.J., Mendibil, K., Mendibil, K., Bititci, U., Daisley, P., Breen, T.H.J.
This paper explains how the improvement of a key business process in a manufacturing company can be interpreted in terms of reliability engineering concepts. A case study is presented to illustrate...
Turner, T. J., Mushotzky, R. F., Yaqoob, T., George, I. M., Snowden, S. L., Netzer, H., ...
We present results from a simultaneous Chandra HETG and XMM-Newton observation of NGC 3516. We find evidence for several narrow components of Fe Kalpha along with a broad line. We consider the...
Kraemer, S. B., Crenshaw, D. M., George, I. M., Netzer, H., Turner, T. J., Gabel, J. R.
We present observations of the UV absorption lines in the Seyfert 1 galaxy NGC 3516, obtained at a resolution of $\lambda$/$\Delta\lambda$ $\approx$ 40,000 with the Space Telescope Imaging...
Kaspi, S., Brandt, W. N., George, I. M., Netzer, H., Crenshaw, D. M., Gabel, J. R., ...
We present results from a 900 ks exposure of NGC 3783 with the High-Energy Transmission Grating Spectrometer on board the Chandra X-ray Observatory. The resulting X-ray spectrum has the best...
Web enabled performance measurement systems (2002)
Bititci, U., Nudurupati, S.S., Turner, T.J.
In order to respond proactively to the new emerging challenges, management requires up-to-date and accurate information on performance. Such performance measurement systems are still not common...
Web enabled performance measurement systems (2002)
Bititci, U., Nudurupati, S.S., Turner, T.J.
In order to respond proactively to the new emerging challenges, management requires up-to-date and accurate information on performance. Such performance measurement systems are still not common...
Web enabled performance measurement systems (2002)
Bititci, U., Nudurupati, S.S., Turner, T.J.
In order to respond proactively to the new emerging challenges, management requires up-to-date and accurate information on performance. Such performance measurement systems are still not common...
The Density and Location of the X-ray Absorbing Gas in NGC 3516 (2001)
Netzer, H., Chelouche, D., George, I. M., Turner, T. J., Crenshaw, D. M., Kraemer, S. B., ...
A new Chandra observation and archival observations by ASCA are used to investigate spectral variations in the Sy1 galaxy NGC 3516 over a period of 7 years. A large change in flux (factor ~50 at...
The Detection of Circumnuclear X-ray Emission from the Seyfert Galaxy NGC 3516 (2001)
George, I. M., Turner, T. J., Netzer, H., Kraemer, S. B., Ruiz, J., Chelouche, D., ...
We present the first high-resolution, X-ray image of the circumnuclear regions of the Seyfert 1 galaxy NGC 3516, using the Chandra X-ray Observatory (CXO). All three of the CXO observations reported...
The Spectral Energy Distribution of the Seyfert galaxy Ton S180 (2001)
Turner, T. J., Romano, P., Kraemer, S. B., George, I. M., Yaqoob, T., Crenshaw, D. M., ...
We present spectral results from a multi-satellite, broad-band campaign on the Narrow-line Seyfert 1 galaxy Ton S180 performed at the end of 1999. We discuss the spectral-energy distribution of the...
Subtleties in Measuring Iron K Lines in AGN (2001)
Yaqoob, T., Padmanabhan, U., Dotani, T., George, I. M., Turner, T. J., Nandra, K.
Chandra and XMM observations are showing that the Fe-K emission lines in type 1 AGN are composite, in general consisting of a narrow and a broad component. We review the latest Chandra HETG results...
Chandra Grating Observations of Seyfert 1 Galaxies (2001)
Yaqoob, T., George, I. M., Turner, T. J.
We present new results from a Chandra HETG observation of NGC 5548 and give a comparison of absorption and emission features found in other Seyfert 1 galaxies using Chandra grating observations. Deep...
Shemmer, O., Romano, P., Bertram, R., Brinkmann, W., Collier, S., Crowley, K. A., ...
We present the results of a 2 yr long optical monitoring program of the narrow-line Seyfert 1 galaxy Ark 564. The majority of this monitoring project was also covered by X-ray observations (RXT E),...
Crenshaw, D. M., Kraemer, S. B., Turner, T. J., Collier, S., Peterson, B. M., Brandt, W. N., ...
We use Hubble Space Telescope UV and optical spectra of the narrow-line Seyfert 1 (NLS1) galaxy Akn 564 to investigate its internal reddening and properties of its emission-line and intrinsic UV...
Edelson, Rick, Turner, T. J., Pounds, Ken, Vaughan, Simon, Markowitz, Alex, Marshall, Herman, ...
The bright, soft X-ray spectrum Seyfert 1 galaxies Ark 564 and Ton S180 were monitored for 35 days and 12 days with ASCA and RXTE (and EUVE for Ton S180). The short time scale (hours-days)...
Romano, P., Turner, T. J., Mathur, S., George, I. M.
We present an analysis of the X-ray variability properties of the NLS1 galaxy Ton S180, based upon a 12-day continuous ASCA observation. We observe flux variations of a factor of 3.5 in the 0.7-1.3...
Shemmer, O., Romano, P., Bertram, R., Brinkmann, W., Collier, S., Crowley, K. A., ...
We present the results of a two-year long optical monitoring program of the narrow-line Seyfert 1 galaxy Akn 564. The majority of this monitoring project was also covered by X-ray observations (RXTE)...
Collier, S., Crenshaw, D. M., Peterson, B. M., Brandt, W. N., Clavel, J., Edelson, R., ...
We present results of an intensive two-month campaign of approximately daily spectrophotometric monitoring of the narrow-line Seyfert 1 galaxy Akn 564 with HST. The fractional variability amplitude...
Turner, T. J., Romano, P., George, I. M., Edelson, R., Collier, S. J., Mathur, S., ...
We present a 35 day ASCA observation of the NLS1 Akn 564, which was part of a multiwavelength AGN Watch monitoring campaign. Akn 564 shows a photon index varying across the range 2.45--2.72. The...
The X-ray Emission from the Nucleus of the Dwarf Elliptical Galaxy NGC 3226 (2001)
George, I. M., Mushotzky, R. F., Yaqoob, T., Turner, T. J., Kraemer, S., Ptak, A. F., ...
We present the first high resolution X-ray image of the dwarf elliptical galaxy NGC 3226. The data were obtained during an observation of the nearby Seyfert Galaxy NGC 3227 using the Chandra X-ray...
The Spectral Energy Distribution of the Seyfert galaxy Ton S180 (2001)
Turner, T. J., Romano, P., Kraemer, S. B., George, I. M., Yaqoob, T., Crenshaw, D. M., ...
We present spectral results from a multi-satellite, broad-band campaign on the Narrow-line Seyfert 1 galaxy Ton S180 performed at the end of 1999. We discuss the spectral-energy distribution of the...
The Spectral Energy Distribution of the Seyfert galaxy Ton S180 (2001)
Turner, T. J., Romano, P., Kraemer, S. B., George, I. M., Yaqoob, T., Crenshaw, D. M., ...
We present spectral results from a multi-satellite, broad-band campaign on the Narrow-line Seyfert 1 galaxy Ton S180 performed at the end of 1999. We discuss the spectral-energy distribution of the...
Chandra Grating Spectroscopy of the Seyfert Galaxy Ton S180 (2000)
Turner, T. J., George, I. M., Yaqoob, T., Kriss, G., Crenshaw, D. M., Kraemer, S., ...
This paper presents results from spectral observations of Ton S180 using Chandra and ASCA. The data confirm the presence of the soft excess but the Chandra LETG spectrum reveals it to be broad and...
Yaqoob, T., George, I. M., Nandra, K., Turner, T. J., Serlemitsos, P. J., Mushotzky, R. F.
We report the detection of a narrow Fe-K emission line in the Seyfert 1 galaxy NGC 5548 with the Chandra High-Energy Transmission Gratings. In the galaxy frame we measure a center energy of 6.40 \pm...
The Origin of the X-ray and Ultraviolet Emission in NGC 7469 (2000)
Nandra, K., Le, T., Edelson, R. A., George, I. M., Mushotzky, R. F., Peterson, B. M., ...
We present a spectral analysis of a 30d, near-continuous observation of the Seyfert 1 galaxy NGC 7469 with RXTE. Daily integrations show strong spectral changes during the observation. Ourmain result...
On The Reddening in X-ray Absorbed Seyfert 1 Galaxies (2000)
Kraemer, S. B., George, I. M., Turner, T. J., Crenshaw, D. M.
There are several Seyfert galaxies for which there is a discrepancy between the small column of neutral hydrogen deduced from X-ray observations and the much greater column derived from the reddening...
BeppoSAX Observation of NGC 7582: Constraints on the X-ray absorber (1999)
Turner, T. J., Perola, G. C., Fiore, F., Matt, G., George, I. M., Piro, L., ...
This paper presents a BeppoSAX observation of NGC 7582 made during 1998 November and an optical spectrum taken in 1998 October. The new X-ray data reveal a previously unknown hard X-ray component in...
X-ray Observations of Optically-Selected, Radio-Quiet Quasars I: The ASCA results (1999)
George, I. M., Turner, T. J., Yaqoob, T., Netzer, H., Laor, A., Mushotzky, R. F., ...
We present the result of 27 ASCA observations of 26 radio-quiet quasars (RQQs) from the PG survey. All the RQQs were detected except 2 BALQSOs. We find the variability characteristics of the sources...
A Highly Doppler Blueshifted Fe-K Emission Line in the High-Redshift QSO PKS 2149-306 (1999)
Yaqoob, T., George, I. M., Nandra, K., Turner, T. J., Zobair, S., Serlemitsos, P. J.
We report the results from an \asca observation of the QSO PKS 2149-306 (z=2.345). We detect an emission line centered at $\sim 17$ keV in the quasar frame. Line emission at this energy has not been...
The properties of the relativistic iron K-line in NGC 3516 (1999)
Nandra, K., George, I. M., Mushotzky, R. F., Turner, T. J., Yaqoob, T.
We present an analysis of the relativistic iron K-alpha line in the Seyfert 1 galaxy NGC 3516, based on a continuous, five-day ASCA observation. The broad profile which has been found in several...
Akn 564: an unusual component in the X-ray spectra of NLSy1 galaxies (1999)
Turner, T. J., George, I. M., Netzer, Hagai
We present an ASCA observation of the NLSy1 Ark 564. The X-ray light curve shows rapid variability, but no evidence for energy-dependence to these variations, within the 0.6 -- 10 keV bandpass. A...
On X-ray Variability in Seyfert Galaxies (1999)
Turner, T. J., George, I. M., Nandra, K., Turcan, D.
This paper presents a quantification of the X-ray variability amplitude for 79 ASCA observations of 36 Seyfert 1 galaxies. We find that consideration of sources with the narrowest permitted lines in...
Are There Any Type 2 QSOs? The Case of AXJ0341.4-4453 (1999)
Halpern, J. P., Turner, T. J., George, I. M.
The X-ray source AXJ0341.4-4453 was described by Boyle et al. as a Type 2 AGN at z = 0.672 based on the absence of broad emission lines in the observed wavelength range 4000-7000 Angstroms. We...
Kraemer, S. B., Turner, T. J., Crenshaw, D. M., George, I. M.
We explore the effects of UV absorbing material on the shape of the EUV continuum radiation emitted by the active galactic nucleus, and on the relative strengths of emission lines, formed in the...
O'Brien, P. T., Dietrich, M., Leighly, K., Alloin, D., Clavel, J., Crenshaw, D. M., ...
As part of an extensive multi-wavelength monitoring campaign, the International Ultraviolet Explorer satellite was used to observe the broad-line radio galaxy 3C 390.3 during the period 1994 December...
X-ray Observations of Mrk 231 (1998)
This paper presents new X-ray observations of Mrk 231, an active galaxy of particular interest due to its large infrared luminosity and the presence of several blueshifted broad absorption line (BAL)...
A Peculiar Emission Line Feature in the X-ray Spectrum of the Quasar PKS 0637-752 (1998)
Yaqoob, T., George, I. M., Turner, T. J., Nandra, K., Ptak, A., Serlemitsos, P. J.
We report the results from an ASCA observation of the high-luminosity, radio-loud quasar PKS 0637-752 (redshift 0.654), covering the 0.8-15 keV band in the quasar-frame. We find the source to have a...
X-ray Observations of the Seyfert galaxy LB 1727 (1H 0419-577) (1998)
Turner, T. J., George, I. M., Nandra, K., Remillard, R. A., Leighly, K. M., Marshall, H. L., ...
We discuss the properties of the Seyfert 1.5 galaxy LB 1727, also known as 1H 0419-577, from X-ray observations obtained by ASCA and ROSAT along with optical observations from earlier epochs. ASCA...
The X-ray Spectral Variability of the Seyfert Galaxy NGC 3227 (1998)
George, I. M., Mushotzky, R. F., Turner, T. J., Yaqoob, T., Ptak, A., Nandra, K., ...
(Abridged) We present the results from {\it ASCA} observations of NGC 3227 along with those from a {\it ROSAT} observation. The 0.6--10 keV continuum is consistent with a powerlaw with $\Gamma \sim...
X-ray Signatures of an Ionized Reprocessor in the Seyfert galaxy Ton S 180 (1998)
Turner, T. J., George, I. M., Nandra, K.
We discuss the hard X-ray properties of the Seyfert galaxy Ton S 180, based upon the analysis of ASCA data. We find the X-ray flux varied by a factor ~2 on a time scale of a few thousand seconds. The...
Nandra, K., Clavel, J., Edelson, R. A., George, I. M., Malkan, M. A., Mushotzky, R. F., ...
We have undertaken near-continuous monitoring of the Seyfert 1 galaxy NGC 7469 in the X-ray with RXTE over a ~30d baseline. The source shows strong variability with a root-mean-square (rms) amplitude...
The Soft X-ray Spectrum of Scattering--Dominated AGN (1998)
Netzer, H., Turner, T. J., George, I. M.
This paper discusses the properties of scattering--dominated active galactic nuclei (AGN). We define these to be AGN for which the direct line-of-sight to the continuum source is obscured by...
ASCA Observations of the Ionized Gas in the Seyfert Galaxy NGC 3783 (1998)
George, I. M., Turner, T. J., Mushotzky, R. F., Nandra, K., Netzer, H.
We present the results from ASCA observations of NGC 3783 carried out during 1993 and 1996. Variability is observed both between the two epochs and within the individual observations, the latter due...
Wanders, I., Peterson, B.M., Alloin, D., Ayres, T.R., Clavel, J., Crenshaw, D.M., ...
From 1996 June 10 to July 29, the International Ultraviolet Explorer monitored the Seyfert 1 galaxy NGC 7469 continuously in an attempt to measure time delays between the continuum and emission-line...
ASCA observations of type-2 Seyfert Galaxies. III. Orientation and X-ray Absorption (1997)
Turner, T. J., George, I. M., Nandra, K., Mushotzky, R. F.
We discuss the spectral properties of a sample of type-2 Seyfert galaxies based upon the analysis of \asca data. In this paper we consider the sources for which the X-ray spectra appear to be...
George, I. M., Turner, T. J., Netzer, Hagai, Nandra, K., Mushotzky, R. F., Yaqoob, T.
(Abridged) We present the results from a detailed analysis of the 0.6 - 10 keV spectra of 23 ASCA observations of 18 objects. We find that in most cases the underlying continuum can be...
On the dependence of the iron K-line profiles with luminosity in Active Galactic Nuclei (1997)
Nandra, K., George, I. M., Mushotzky, R. F., Turner, T. J., Yaqoob, T.
We present evidence for changes in the strength and profile of the iron K-alpha line in Active Galactic Nuclei (AGN), based on X-ray observations with ASCA. There is a clear decrease in the strength...
Evidence for Absorption due to Highly-Ionized Gas in the Radio-quiet Quasar PG 1114+445 (1997)
George, I. M., Nandra, K., Laor, A., Turner, T. J., Fiore, F., Netzer, H., ...
We present results on the X-ray spectrum of the quasar PG 1114+445 from an ASCA observation performed in 1996 June, and a ROSAT observation performed 3 years earlier. We show good agreement between...
Turner, T. J., George, I. M., Nandra, K., Mushotzky, R. F.
We discuss the importance of X-ray scattering and Compton reflection in type-2 Seyfert galaxies, based upon the analysis of ASCA observations of 25 such sources. Consideration of the iron Kalpha, [O...
ASCA observations of Seyfert 1 galaxies: I. Data Analysis, Imaging and Timing (1996)
Nandra, K., George, I. M., Mushotzky, R. F., Turner, T. J., Yaqoob, T.
We present the first in a series of papers describing the X-ray properties of a sample of 18 Seyfert 1 galaxies, using data obtained by \asca. The imaging data reveal a number of serendipitous hard...
Variability of the iron K-emission line in the Seyfert 1 galaxy NGC 3516 (1996)
Nandra, K., Mushotzky, R. F., Yaqoob, T., George, I. M., Turner, T. J.
We present strong evidence for variability of the flux of the iron K$\alpha$ emission line in the Seyfert 1 galaxy, NGC 3516. Two ASCA observations, separated by $\sim 1$~yr, showed a marked decrease...
ASCA observations of Seyfert 1 galaxies: II. Relativistic Iron K-alpha emission (1996)
Nandra, K., George, I. M., Mushotzky, R. F., Turner, T. J., Yaqoob, T.
We present evidence for widespread relativistic effects in the central regions of active galactic nuclei. In a sample of 18 Seyfert 1 galaxies observed by \asca, 14 show an iron K$\alpha$ line which...
ASCA Observations of the Composite Warm Absorber in NGC 3516 (1996)
Kriss, G. A., Krolik, J. H., Otani, C., Espey, B. R., Turner, T. J., Kii, T., ...
We obtained X-ray spectra of the Seyfert 1 galaxy NGC~3516 in March 1995 using ASCA. Simultaneous far-UV observations were obtained with HUT on the Astro-2 shuttle mission. The ASCA spectrum shows a...
ASCA and ROSAT observations of NRAO 140 and IX Per (1995)
Turner, T J, George, I M, Madejski, G M, Kitamoto, S, Suzuki, T
X-ray spectrum and variability of the quasar PG1211+143 (1994)
Yaqoob, T, Serlemitsos, P J, Mushotzky, R F, Madejski, G M, Turner, T J, Kunieda, H
Multiple Ca2+ channel types coexist to regulate synaptosomal neurotransmitter release.
Turner, T J, Adams, M E, Dunlap, K
The regulation of excitation-secretion coupling by Ca2+ channels is a fundamental property of the nerve terminal. Peptide toxins that block specific Ca2+ channel types have been used to identify...
Multiple Ca2+ channel types coexist to regulate synaptosomal neurotransmitter release.
Turner, T J, Adams, M E, Dunlap, K
The regulation of excitation-secretion coupling by Ca2+ channels is a fundamental property of the nerve terminal. Peptide toxins that block specific Ca2+ channel types have been used to identify...
Poisoning: Effective Clinical Intervention
Poisoning accounts for 40-60% of suicides, is the commonest medical emergency in small children, and an important source of occupational injury. Prevention of unintentional poisoning involves...