An HST/WFPC2 survey of bright young clusters in M31. IV. Ages and mass estimates (2009)
Perina, S., Cohen, J. G., Barmby, P., Beasley, M. A., Bellazzini, M., Brodie, J. P., ...
{Aims.} We present the main results of an imaging survey of possible young massive clusters (YMC) in M31 performed with the Wide Field and Planetary Camera2 (WFPC2) on the Hubble Space Telescope...
An HST/WFPC2 Survey of Bright Young Clusters in M31 III. Structural Parameters (2009)
Barmby, P., Perina, S., Bellazzini, M., Cohen, J. G., Hodge, P. W., Huchra, J. P., ...
Surface brightness profiles for 23 M31 star clusters were measured using images from the Wide Field Planetary Camera 2 on the Hubble Space Telescope, and fit to two types of models to determine the...
Hodge, P. W., Krienke, O. K., Bellazzini, M., Perina, S., Barmby, P., Cohen, J. G., ...
We report on the properties of 89 low-mass star clusters located in the vicinity of luminous young clusters ("blue globulars") in the disk of M31. Eighty-two of the clusters are newly detected. We...
M31 Globular Cluster Abundances from High-Resolution, Integrated-Light Spectroscopy (2009)
Colucci, J. E., Bernstein, R. A., Cameron, S., McWilliam, A., Cohen, J. G.
We report the first detailed chemical abundances for 5 globular clusters (GCs) in M31 from high-resolution (R ~ 25,000) spectroscopy of their integrated light. These GCs are the first in a larger set...
High-resolution (R ≈ 100,000), high signal-to-noise spectra of M71 giants have been obtained with High Resolution Echelle Spectrometer at the Keck I telescope in order to measure their Mg isotopic...
Hodge, P. W., Krienke, O. K., Bellazzini, M., Perina, S., Barmby, P., Cohen, J. G., ...
We report on the properties of 89 low mass star clusters located in the vicinity of luminous young clusters (blue globulars) in the disk of M31. 82 of the clusters are newly detected. We have...
Perina, S., Barmby, P., Beasley, M. A., Bellazzini, M., Brodie, J. P., Burstein, D., ...
Aims. We introduce our imaging survey of possible young massive globular clusters in M31 performed with the Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space Telescope (HST). We obtained...
Perina, S., Barmby, P., Beasley, M. A., Bellazzini, M., Brodie, J. P., Burstein, D., ...
{Aims.} We introduce our imaging survey of possible young massive globular clusters in M31 performed with the Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space Telescope (HST). We present...
Schoerck, T., Christlieb, N., Cohen, J. G., Beers, T. C., Shectman, S., Thompson, I., ...
We determine the metallicity distribution function (MDF) of the Galactic halo by means of a sample of 1638 metal-poor stars selected from the Hamburg/ESO objective-prism survey (HES). The sample was...
Remote observing with the Keck Telescope from California using NASA's ACTS satellite (2007)
P. L. Shopbell, J. G. Cohen, L. Bergman
As a technical demonstration project for the NASA Advanced Communications Technology Satellite (ACTS), we have implemented remote observing on the 10-meter Keck II telescope on Mauna Kea in Hawaii...
An Update on the 0Z Project (2007)
Cohen, J. G., Christlieb, N., McWilliam, A., Shectman, S., Thompson, I.
We give an update on our 0Z Survey to find more extremely metal poor (EMP) stars with [Fe/H] < -3 dex through mining the database of the Hamburg/ESO Survey. We present the most extreme such stars we...
Wittman, D., Dell'Antonio, I. P., Hughes, J. P., Margoniner, V. E., Tyson, J. A., Cohen, J. G., ...
We present the first sample of galaxy clusters selected on the basis of their weak gravitational lensing shear. The shear induced by a cluster is a function of its mass profile and its redshift...
Weak Lensing Discovery and Tomography of a Cluster at z=0.68 (2002)
Wittman, D., Margoniner, V. E., Tyson, J. A., Cohen, J. G., Dell'Antonio, I. P., Becker, A. C.
We report the weak lensing discovery, spectroscopic confirmation, and weak lensing tomography of a massive cluster of galaxies at $z=0.68$, demonstrating that shear selection of clusters works at...
Time delay and lens redshift for the doubly imaged BAL quasar SBS1520+530 (2002)
Burud, I., Hjorth, J., Courbin, F., Cohen, J. G., Magain, P., Jaunsen, A. O., ...
We present optical R-band light curves of the gravitationally lensed quasar SBS1520+530 derived from data obtained at the Nordic Optical Telescope. A time delay of 130+/-3 days (1 sigma) is...
Discovery of a Galaxy Cluster via Weak Lensing (2001)
Wittman, D., Tyson, J. A., Margoniner, V. E., Cohen, J. G., Dell'Antonio, I. P.
We report the discovery of a cluster of galaxies via its weak gravitational lensing effect on background galaxies, the first spectroscopically confirmed cluster to be discovered through its...
Near Infrared Observations of the Extremely Red Object CL0939+4713B: An Old Galaxy at z~1.58? (1999)
Soifer, B. T., Matthews, K., Neugebauer, G., Armus, L., Cohen, J. G., Persson, S. E., ...
Near infrared imaging and spectroscopic observations of the extremely red object (R-K~ 7 mag) CL 0939+4713 B have been obtained with the Near Infrared Camera on the Keck I Telescope of the W. M. Keck...
The Spectra of Main Sequence Stars in Galactic Globular Clusters I. CH and CN Bands in M13 (1999)
Spectra with a high signal-to-noise ratio of 50 stars which are just below the main sequence turnoff and are members of M13 are presented. They yield indices for the strength of the CH and the...
The Spectra of Main Sequence Stars in Galactic Globular Clusters II. CH and CN Bands in M71 (1999)
Spectra with a high signal-to-noise ratio of 79 stars which are just below the main sequence turnoff of M71 are presented. They yield indices for the strength of the G band of CH and the ultraviolet...
B2045+265: A New Four-Image Gravitational Lens from CLASS (1998)
Fassnacht, C. D., Blandford, R. D., Cohen, J. G., Matthews, K., Pearson, T. J., Readhead, A. C. S., ...
We have discovered a new gravitational lens in the Cosmic Lens All-Sky Survey (CLASS). B2045+265 is a four-image system with a maximum separation of 1.9 arcsec. A fifth radio component is detected,...
Fassnacht, C. D., Cohen, J. G.
We present spectra of three gravitational lens systems taken with the Low Resolution Imaging Spectrograph on the W. M. Keck Telescopes. All of the systems were discovered in the JVAS and CLASS radio...
Faint M-dwarfs and the structure of the Galactic disk (1997)
Reid, I. N., Gizis, J. E., Cohen, J. G., Pahre, M. A., Hogg, D. W., Cowie, L., ...
We use broadband photometry and low-resolution spectra of a complete sample of late-K and M dwarfs brighter than I=22 in three fields at high galactic latitude to study issues relating to galactic...
Blue Horizontal Branch Stars in M92 (1997)
We have analyzed high dispersion and high precision spectra of 5 blue horizontal branch stars in the globular cluster M92 to establish that the projected rotational velocity for these stars ranges...
A Spectroscopic Survey for Binary Stars in the Globular Cluster NGC5053 (1996)
We carried out a radial velocity survey for spectroscopic binaries in the low density globular cluster NGC5053. Our sample contains a total of 77 cluster member giant and subgiant stars with visual...
Cowie, Lennox L., Songaila, Antoinette, Hu, Esther M., Cohen, J. G.
We present the results of spectroscopic studies with the LRIS spectrograph on Keck of two of the Hawaii deep survey fields. The 393 objects observed cover an area of 26.2 square arcmin and constitute...
Strong Redshift Clustering of Distant Galaxies (1996)
Cohen, J. G., Hogg, D. W., Pahre, M. A., Blandford, R.
We present initial results from a redshift survey carried out with the Low Resolution Imaging Spectrograph on the 10~m W. M. Keck Telescope of a field 14.6 arc-min$^2$ in solid angle. In the redshift...