Discovery of a bright transient ultraluminous X-ray source Suzaku J1305-4931 in NGC 4945 (2007)
Isobe, Naoki, Kubota, Aya, Makishima, Kazuo, Gandhi, Poshak, Griffiths, Richard E., Dewangan, Gulab C., ...
This paper reports the discovery of a bright X-ray transient source, Suzaku J1305-4913, in the south-west arm of the nearby Seyfert II galaxy NGC 4945. It was detected at a 0.5 -- 10 keV flux of $2.2...
Suzaku wide-band X-ray Spectroscopy of the Seyfert 2 AGN in NGC 4945 (2007)
Itoh, Takeshi, Done, Chris, Makishima, Kazuo, Madejski, Grzegorz, Awaki, Hisamitsu, Isobe, Naoki, ...
Suzaku observed a nearby Seyfert 2 galaxy NGC4945, which hosts one of the brightest active galactic nuclei above 20 keV. Combining data from the X-ray CCD camera (XIS) and the Hard X-ray Detector...
The X-ray observatory Suzaku (2007)
Mitsuda, Kazuhisa, Bautz, Mark, Inoue, Hajime, Kelley, Richard L., Koyama, Katsuji, Kunieda, Hideyo, ...
Miyaji, Takamitsu, Zamorani, Giovanni, Cappelluti, Nico, Gilli, Roberto, Griffiths, Richard E., Comastri, Andrea, ...
Miyaji, Takamitsu, Zamorani, Giovanni, Cappelluti, Nico, Gilli, Roberto, Griffiths, Richard E., Comastri, Andrea, ...
We present the first results of the measurements of angular auto-correlation functions (ACFs) of X-ray point sources detected in the XMM-Newton observations of the 2 deg2 COSMOS field (XMM-COSMOS). A...
Yaqoob, Tahir, Murphy, Kendrah D., Griffiths, Richard E., Haba, Yoshito, Inoue, Hajime, Itoh, Takeshi, ...
We present detailed time-averaged X-ray spectroscopy in the 0.5--10 keV band of the Seyfert~1.9 galaxy NGC 2992 with the Suzaku X-ray Imaging Spectrometers (XIS). We model the complex continuum in...
Black Hole Mass of the Ultraluminous X-ray source M82 X-1 (2005)
Dewangan, Gulab C., Titarchuk, Lev, Griffiths, Richard E.
We report the first clear evidence for the simultaneous presence of a low frequency break and a QPO in the fluctuation power spectrum of a well known ultraluminous X-ray source (ULX) in M82 using...
XMM-Newton view of the ultra-luminous X-ray sources in M51 (2005)
Dewangan, Gulab C., Griffiths, Richard E., Choudhury, Manojendu, Miyaji, Takamitsu, Schurch, Nicholas J.
(Abridged) We present results based on XMM-Newton observation of the nearby spiral galaxy M51 (NGC5194 and NGC5195). Two ULXs in NGC5194 show evidence for short-term variability, and all but two ULXs...
Detection of the Tip of Red Giant Branc in NGC 5128 (2004)
Soria, Roberto, Mould, Jeremy R., Watson, Alan M., Gallagher, John S. III, Ballester, Gilda E., Burrows, Christopher J., ...
We present a color-magnitude diagram of more than 10,000 stars in the halo of galaxy NGC 5128 (Centaurus A), based on WFPC2 images through the V and I filters. The position of the red-giant branch...
Multiwavelength Properties of the X-ray Sources in the Groth-Westphal Strip Field (2004)
Miyaji, Takamitsu, Sarajedini, Vicki, Griffiths, Richard E., Yamada, Toru, Schurch, Matthew, Cristóbal-Hornillos, David, ...
We summarize the multiwavelength properties of X-ray sources detected in the 80 ks XMM-Newton observation of the Groth-Westphal Strip. We find 23 XMM-Newton sources within the WFPC2 fields. Ten...
A transition to a low/soft state in the ultra-luminous compact X-ray source Holmberg II X-1 (2004)
Dewangan, Gulab C., Miyaji, Takamitsu., Griffiths, Richard E., Lehmann, Ingo
We present three XMM-Newton observations of the ultra-luminous compact X-ray source Holmberg II X-1 in its historical brightest and faintest states. The source was in its brightest state in April...
A transition to a low/soft state in the ultraluminous compact X-ray source Holmberg II X-1 (2004)
Dewangan, Gulab C., Miyaji, Takamitsu, Griffiths, Richard E., Lehmann, Ingo
Cosmic Gravitational Shear from the HST Medium Deep Survey (2003)
Casertano, Stefano, Ratnatunga, Kavan U., Griffiths, Richard E.
We present a measurement of cosmic shear on scales ranging from $ 10\arcsec $ to $ 2\arcmin $ in 347 WFPC2 images of random fields. Our result is based on shapes measured via image fitting and on a...
Turnshek, David A., Rao, Sandhya M., Ptak, Andrew F., Griffiths, Richard E., Monier, Eric M.
Chandra X-Ray Observatory (CXO) ACIS-S spectra of three quasars which lie behind three foreground damped Lyman alpha (DLA) absorbers are analyzed in order to attempt to determine the amount of...
Faint Source Counts from the Off-source fluctuation Analysis on the Deepest Chandra Fields (2002)
Miyaji, Takamitsu, Griffiths, Richard E.
We show the results of the fluctuation analysis applied to the off-source areas from the two 1 Million second Chandra Deep Fields, including our new results on the Chandra Deep Field-South (CDF-S) in...
Miyaji, Takamitsu, Griffiths, Richard E.
We report the results of fluctuation analysis of the off-source field from the 1 Million second Chandra observation of the Hubble Deep Field-North (HDF-N). The distribution of the counts in cells has...
Detection of Nuclear X-ray Sources in Nearby Galaxies with Chandra (2001)
Ho, Luis C., Feigelson, Eric D., Townsley, Leisa K., Sambruna, Rita M., Garmire, Gordon P., Brandt, W. N., ...
We report preliminary results from an arcsecond-resolution X-ray survey of nearby galaxies using ACIS on board Chandra. The total sample consists of 41 low-luminosity AGNs, including Seyferts,...
Coyote responses to changing jackrabbit abundance affect sheep predation (2001)
Stoddart, L. Charles, Griffiths, Richard E., Knowlton, Frederick F.
Domestic sheep ranchers generally perceive abundances of natural prey and coyotes (Canis latrans) as important factors affecting coyote predation rates on sheep. To determine the effect of a changing...
Stellar Populations at the Center of IC 1613 (1999)
Cole, Andrew A., Tolstoy, Eline, Gallagher, John S., Hoessel, John G., Mould, Jeremy R., Holtzman, Jon A., ...
We have observed the center of the Local Group dwarf irregular galaxy IC 1613 with WFPC2 aboard the Hubble Space Telescope in the F439W, F555W, and F814W filters. We find a dominant old stellar...
WFPC2 Observations of Compact Star Cluster Nuclei in Low Luminosity Spiral Galaxies (1999)
Matthews, Lynn D., Gallagher, John S., Krist, John E., Watson, Alan M., Burrows, Christopher J., ...
We have used the Wide Field Planetary Camera 2 aboard the Hubble Space Telescope to image the compact star cluster nuclei of the nearby, late-type, low-luminosity spiral galaxies NGC 4395, NGC 4242,...
Disk and Bulge Morphology of WFPC2 galaxies: The HST Medium Deep Survey database (1999)
Ratnatunga, Kavan U., Griffiths, Richard E., Ostrander, Eric J.
Quantitative morphological and structural parameters are estimated for galaxies detected in HST observations of WFPC2 survey fields. A modeling approach based on maximum likelihood has been developed...
Compact Nuclei in Galaxies at Moderate Redshift: I. Imaging and Spectroscopy (1998)
Sarajedini, Vicki L., Green, Richard F., Griffiths, Richard E., Ratnatunga, Kavan
This study explores the space density and properties of active galaxies to z=0.8. We have investigated the frequency and nature of unresolved nuclei in galaxies at moderate redshift as indicators of...
Sarajedini, Vicki L., Green, Richard F., Griffiths, Richard E., Ratnatunga, Kavan
This study explores the space density and properties of active galaxies to z=0.8. We have investigated the frequency and nature of unresolved nuclei in galaxies at moderate redshift as indicators of...
Tyson, J. Anthony, Fischer, Philippe, Guhathakurta, Puragra, McIlroy, Peter, Wenk, R. A., Huchra, John P., ...
Deep Hubble Space Telescope Wide Field Camera (WFC-1) imaging of a region 3farcm7 east of the V = 13 mag Seyfert galaxy NGC 5548 in the F555W and F785LP bands, and deep ground-based V and I imaging,...
The physical parameters of the evolving population of faint galaxies (1998)
Glazebrook, Karl, Abraham, Roberto G., Santiago, Basilio X., Ellis, Richard S., Griffiths, Richard E.
The excess number of blue galaxies at faint magnitudes is a subject of much controversy. Recent Hubble Space Telescope results have revealed a plethora of galaxies with peculiar morphologies...
Tyson, J. Anthony, Fischer, Philippe, Guhathakurta, Puragra, McIlroy, Peter, Wenk, R. A., Huchra, John P., ...
Deep Hubble Space Telescope Wide Field Camera (WFC-1) imaging of a region 3farcm7 east of the V = 13 mag Seyfert galaxy NGC 5548 in the F555W and F785LP bands, and deep ground-based V and I imaging,...
The physical parameters of the evolving population of faint galaxies (1998)
Glazebrook, Karl, Abraham, Roberto G., Santiago, Basilio X., Ellis, Richard S., Griffiths, Richard E.
The excess number of blue galaxies at faint magnitudes is a subject of much controversy. Recent Hubble Space Telescope results have revealed a plethora of galaxies with peculiar morphologies...
Im, Myungshin, Griffiths, Richard E., Ratnatunga, Kavan U.
We have identified seven (field) elliptical galaxies acting as strong gravitational lenses and have used them to measure cosmological parameters. To find the most likely value for Omega_m (=...
Compact Nuclei in Moderately Redshifted Galaxies (1996)
Sarajedini, Vicki L., Green, Richard F., Griffiths, Richard E., Ratnatunga, Kavan U.
The Hubble Space Telescope WFPC2 is being used to obtain high-resolution images in the V and I bands for several thousand distant galaxies as part of the Medium Deep Survey (MDS). An important...
A deep ROSAT Survey - XII. The X-ray spectra of faint ROSAT sources (1996)
Almaini, Omar, Shanks, Tom, Boyle, Brian J., Griffiths, Richard E., Roche, Nathan, Stewart, Gordon C., ...
Optical spectroscopy has enabled us to identify the optical counterparts to over 200 faint X-ray sources to a flux limit of S_(0.5-2keV)=4x10^-15 erg s^-1 cm^-2 on 5 deep ROSAT fields. Here we...
A deep ROSAT Survey X: X-ray Luminous Narrow Emission Line Galaxies (1996)
Griffiths, Richard E., Della Ceca, Roberto, Georgantopoulos, Ioannis, Boyle, Brian J., Stewart, Gordon C., Shanks, Tom, ...
X-ray luminous narrow emision-line galaxies (NELG) have been previously identified and proposed as an important class of extragalactic X-ray sources, with a potentially significant contribution to...
Luminosity Functions of Elliptical Galaxies at z < 1.2 (1996)
Im, Myungshin, Griffiths, Richard E., Ratnatunga, Kavan U., Sarajedini, Vicki L.
The luminosity functions of E/S0 galaxies are constructed in 3 different redshift bins (0.2 < z < 0.55, 0.55 < z < 0.8, 0.8 < z < 1.2), using the data from the Hubble Space Telescope Medium Deep...
Morphological number-counts from the ultradeep HST images (1995)
Driver, Simon P., Windhorst, Rogier A., Griffiths, Richard E.
We discuss the observations leading to the Faint Blue Galaxy problem and the uncertainties upon which faint galaxy models are based. Using deep Hubble Space Telescope (HST) imaging with the Wide...
Driver, Simon P., Windhorst, Rogier A., Ostrander, Eric J., Keel, William C., Griffiths, Richard E., Ratnatunga, Kavan U.
We determine the morphological mix of field galaxies down to $m_{I}\simeq 24.25$ mag ($m_{B}\sim 26.0$ mag) from a single ultradeep HST WFPC2 image in both the $V_{606}$ and $I_{814}$ filters. In...
Caught in the act: The identification of the galaxies responsible for the faint blue excess (1995)
Driver, Simon P., Windhorst, Rogier A., Griffiths, Richard E.
We summarise recent Hubble Space Telescope results on the morphology of faint field galaxies. Our two principle results are: (1) the galaxies responsible for the faint blue excess have...
Driver, Simon P., Windhorst, Rogier A., Griffiths, Richard E.
We present a complete morphologically classified sample of 144 faint field galaxies from the HST Medium Deep Survey with 20.0 < I 0.5 at I = 21.75 mag.
New "Einstein Cross" Gravitational Lens Candidates in HST WFPC2 Survey Images (1995)
Ratnatunga, Kavan U., Ostrander, Eric J., Griffiths, Richard E., Im, Myungshin
We report the serendipitous discovery of ``Einstein cross'' gravitational lens candidates using the Hubble Space Telescope. We have so far discovered two good examples of such lenses, each in the...
The theta-z relation for HST bulges and disks out to z similar or equal to 0.8 (1994)
Mutz, Steven B., Windhorst, Rogier A., Schmidtke, Paul C., Pascarelle, Sebastian M., Griffiths, Richard E., Ratnatunga, Kavan U., ...
We present HST scale lengths and ground-based redshifts for 63 faint field galaxies down to 1 ≲ 21.5 mag from the Medium-Deep Survey. These have measured redshifts z ≲ 0.8 and half-light...
The theta-z relation for HST bulges and disks out to z similar or equal to 0.8 (1994)
Mutz, Steven B., Windhorst, Rogier A., Schmidtke, Paul C., Pascarelle, Sebastian M., Griffiths, Richard E., Ratnatunga, Kavan U., ...
We present HST scale lengths and ground-based redshifts for 63 faint field galaxies down to 1 ≲ 21.5 mag from the Medium-Deep Survey. These have measured redshifts z ≲ 0.8 and half-light...
REPELLENT OR AVERSIVE CHEMICALS IN SHEEP NECK COLLARS DID NOT DETER COYOTE ATTACKS (1984)
Burns, Richard J., Connolly, Guy E., Griffiths , Richard E.
Since 1974 the Fish and Wildlife Service has studied a "toxic collar" to poison coyotes that attack collared sheep and goats. The collar patent (McBride 1974) indicates that the same collar could...
TOXIC COLLAR FOR CONTROL OF SHEEP-KILLING COYOTES: A PROGRESS REPORT (1978)
Connolly, Guy E., Griffiths, Richard E., Savarie, Peter J.
The toxic sheep collar is the most selective method known for killing coyotes that prey on domestic sheep. The concept dates back to the early 1900's, and has been studied at the Denver Wildlife...
COYOTES, SHEEP AND LITHIUM CHLORIDE (1978)
Griffiths, Richard E., Connolly, Guy E., Burns, Richard J., Sterner, Ray T.
The use of LiCl-treated baits and carcasses has been advocated as a means of controlling coyote predation on sheep through a process known as "aversive conditioning or taste aversion." While some...