A Comprehensive X-ray Spectral Analysis of the Seyfert 1.5 NGC 3227 (2008)
Markowitz, A., Reeves, J. N., George, I. M., Braito, V., Smith, R., Vaughan, S., ...
We present results of a 100 ks XMM observation of the Seyfert 1.5 NGC 3227. Our best-fit broadband model to the pn spectrum consists of a moderately flat (photon index 1.57) hard X-ray power-law...
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...
An XMM-Newton survey of broad iron lines in Seyfert galaxies (2007)
Nandra, K., O'Neill, P. M., George, I. M., Reeves, J. N.
We present an analysis of the X-ray spectra of a sample of 37 observations of 26 Seyfert galaxies observed by XMM-Newton in order to characterize their iron K emission. All objects show evidence for...
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....
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...
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...
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., ...
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., ...
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...
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
Kraemer, S. B., George, I. M., Crenshaw, D. M., Gabel, J. R.
We have explored the relationship between the [O III] $\lambda$5007 and the 2--10 keV luminosities for a sample of Broad- and Narrow-Line Seyfert 1 galaxies (BLSy1 and NLSy1, respectively). We find...
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...
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...
X-ray fluctuation power spectral densities of Seyfert 1 galaxies (2003)
Markowitz, A., Edelson, R., Vaughan, Simon, Uttley, P., George, I.M., Griffiths, R.E., ...
The definitive version of this paper is available from http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v593n1/56874/56874.html
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...
X-ray Fluctuation Power Spectral Densities of Seyfert 1 Galaxies (2003)
Markowitz, A., Edelson, R., Vaughan, S., Uttley, P., George, I. M., Griffiths, R. E., ...
By combining complementary monitoring observations spanning long, medium and short time scales, we have constructed power spectral densities (PSDs) of six Seyfert~1 galaxies. These PSDs span...
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., 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...
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...
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...
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...
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...
Kraemer, S. B., Crenshaw, D. M., Hutchings, J. B., George, I. M., Danks, A. C., Gull, T. R., ...
We have examined the physical conditions in intrinsic UV-absorbing gas in the Seyfert galaxy NGC 4151, using echelle spectra obtained with the Space Telescope Imaging Spectrograph (STIS). We confirm...
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...
The variable XMM-Newton spectrum of Markarian 766 (2000)
Page, M. J., Mason, K. O., Carrera, F. J., Clavel, J., Kaastra, J. S., Puchnarewicz, E. M., ...
The narrow-line Seyfert 1 galaxy Markarian 766 was observed for 60 ks with the XMM-Newton observatory. The source shows a complex X-ray spectrum. The 2-10 keV spectrum can be adequately represented...
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...
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...
X-ray spectrum of the high polarization quasar PKS 1510-089 (1997)
Singh, K. P., Shrader, C. R., George, I. M.
We present results on the X-ray spectra of the radio-loud, high-polarization quasar, PKS 1510-089, based on new data obtained using ASCA, and from archival ROSAT data. The X-ray spectrum obtained by...
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...
The average X-ray/gamma-ray spectrum of radio-quiet Seyfert 1s (1996)
Gondek, D., Zdziarski, A. A., Johnson, W. N., George, I. M., McNaron-Brown, K., Magdziarz, P., ...
We have obtained the average 1--500 keV spectrum of radio-quiet Seyfert 1s using data from EXOSAT, Ginga, HEAO, and GRO/OSSE. The spectral fit to the combined average EXOSAT and OSSE data is fully...
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...
The next generation X-ray observatory (1995)
White, N E, Petre, R, Boldt, E A, Holt, S S, Serlemitsos, P J, Marshall, F E, ...
ASCA and ROSAT observations of NRAO 140 and IX Per (1995)
Turner, T J, George, I M, Madejski, G M, Kitamoto, S, Suzuki, T
Hughes, H M, George, I M, Evans, J C, Rowlands, C C, Powell, G M, Curtis, C G
Halothane or CCl4 was co-administered with the spin trap N-tert-butyl-alpha-(4-nitrophenyl)nitrone (PBN) to rats fitted with bile duct cannuli or to isolated perfused liver preparations. Rats...
Hughes, H M, George, I M, Evans, J C, Rowlands, C C, Powell, G M, Curtis, C G
Halothane or CCl4 was co-administered with the spin trap N-tert-butyl-alpha-(4-nitrophenyl)nitrone (PBN) to rats fitted with bile duct cannuli or to isolated perfused liver preparations. Rats...