What Lies Beneath: Using p(z) to Reduce Systematic Photometric Redshift Errors (2009)
We use simulations to demonstrate that photometric redshift "errors" can be greatly reduced by using the photometric redshift probability distribution p(z) rather than a one-point estimate such as...
Shear-Selected Clusters From the Deep Lens Survey III: Masses from Weak Lensing (2009)
Abate, Alexandra, Wittman, D., Margoniner, V. E., Bridle, S. L., Gee, Perry, Tyson, J. Anthony, ...
We present weak lensing mass estimates of seven shear-selected galaxy cluster candidates from the Deep Lens Survey. The clusters were previously identified as mass peaks in convergence maps of 8.6...
Shaping Attitudes Toward Science in an Introductory Astronomy Class (2009)
At many universities, astronomy is a popular way for non-science majors to fulfill a general education requirement. Because general-education astronomy may be the only college-level science course...
Dark Matter Structures in the Universe: Prospects for Optical Astronomy in the Next Decade (2009)
Marshall, P. J., Auger, M., Bartlett, J. G., Bradac, M., Cooray, A., Dalal, N., ...
The Cold Dark Matter theory of gravitationally-driven hierarchical structure formation has earned its status as a paradigm by explaining the distribution of matter over large spans of cosmic distance...
LSST and the Dark Sector: Image Processing Challenges (2008)
Tyson, J. A., Roat, C., Bosch, J., Wittman, D.
Next generation probes of dark matter and dark energy require high precision reconstruction of faint galaxy shapes from hundreds of dithered exposures. Current practice is to stack the images. While...
M. Lloyd-hart, R. Angel, B. Jacobsen, D. Wittman, E. Kibblewhite, ...
A 0.5 W beam from a continuous-wave dye laser, tuned to the D 2 resonance of atomic sodium, has been used to generate an artificial guide star by illuminating the mesospheric sodium layer, 90 km...
Diffraction-limited K-band imaging at the Multiple Mirror Telescope with adaptive optics (2007)
M. Lloyd-hart, D. Colucci, D. Wittman, B. Mcleod, A. Ghez, ...
Low spatial frequencies of atmospheric turbulence are specially troublesome to astronomers because the phase distortions they cause have large amplitude. We have begun experiments at the Multiple...
M. Lloyd-hart, R. Angel, B. Jacobsen, D. Wittman, D. Mccarthy, ...
A sodium guide star has been used to sense and correct atmospheric aberration during two runs at the Multiple Mirror Telescope (MMT). For the first run in 1993 May, the artificial star was created by...
Diffraction-limited K-band imaging at the Multiple Mirror Telescope with adaptive optics (2007)
Lloyd-Hart Colucci, M. Lloyd-hart, D. Colucci, D. Wittman, B. Mcleod, A. Ghez, ...
Low spatial frequencies of atmospheric turbulence are specially troublesome to astronomers because the phase distortions they cause have large amplitude. We have begun experiments at the Multiple...
Lloyd-Hart Angel, R. Angel, B. Jacobsen, D. Wittman, D. Mccarthy, E. Kibblewhite, ...
A sodium guide star has been used to sense and correct atmospheric aberration during two runs at the Multiple Mirror Telescope (MMT). For the first run in 1993 May, the artificial star was created by...
Progress in Diffraction-Limited Imaging at the Multiple Mirror Telescope with Adaptive Optics (2007)
M. Lloyd-hart, R. Dekany, D. Sandler, D. Wittman, R. Angel, D. Mccarthy
this paper were obtained using only the five mirrors highlighted in Fig. 1. With no aberration, the point spread function of this array appears as shown in Fig. 2, with a bright central peak...
Steward Observatory, M. Lloyd-hart, R. Angel, B. Jacobsen, D. Wittman, E. Kibblewhite, ...
A 0.5 W beam from a continuous-wave dye laser, tuned to the D 2 resonance of atomic sodium, has been used to generate an artificial guide star by illuminating the mesospheric sodium layer, 90 km...
D. Wittman, J. A. Tyson, G. M. Bernstein, R. W. Lee, I. P. Dell'antonio, P. Fischer, ...
The Big Throughput Camera (BTC) recently celebrated its first anniversary as a user instrument on the Blanco 4-meter telescope at Cerro Tololo Interamerican Observatory (CTIO), where it collects more...
G. M. Bernstein, R. C. Nichol, J. A. Tyson, M. P. Ulmer, D. Wittman
We determine the luminosity function (LF) of galaxies in the core of the Coma cluster for MR \Gamma11:4 (assuming H 0 = 75 km s \Gamma1
Photometric Redshifts and Photometry Errors (2007)
Wittman, D., Riechers, P., Margoniner, V. E.
We examine the impact of non-Gaussian photometry errors on photometric redshift performance. We find that they greatly increase the scatter, but this can be mitigated to some extent by incorporating...
The Shear Testing Programme - I. Weak lensing analysis of simulated ground-based observations (2006)
Heymans, C., Van Waerbeke, L., Bacon, D., Berge, J., Bernstein, G., Bertin, E., ...
The Shear Testing Programme (STEP) is a collaborative project to improve the accuracy and reliability of all weak lensing measurements in preparation for the next generation of wide-field surveys. In...
Fassnacht, C. D., McKean, J. P., Koopmans, L. V. E., Treu, T., Blandford, R. D., Auger, M. W., ...
We report the serendipitous discovery of two strong gravitational lens candidates (ACS J160919+6532 and ACS J160910+6532) in deep images obtained with the Advanced Camera for Surveys on the Hubble...
Spurious Shear from the Atmosphere in Ground-Based Weak Lensing Observations (2005)
Weak lensing observations have the potential to be even more powerful than cosmic microwave background (CMB) observations in constraining cosmological parameters. However, the practical limits to...
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 Results from the 75 Square Degree CTIO Survey (2002)
Jarvis, M., Bernstein, G., Jain, B., Fischer, P., Smith, D., Tyson, J. A., ...
We measure seeing-corrected ellipticities for 2 x 10^6 galaxies with magnitude R30\arcmin, ellipticity correlations are detected at high significance and exhibit nearly the pure "E-mode" behavior...
Wittman, D., Tyson, J. A., Dell'Antonio, I. P., Becker, A. C., Margoniner, V. E., Cohen, J., ...
The Deep Lens Survey (DLS) is a deep BVRz' imaging survey of seven 2x2 degree fields, with all data to be made public. The primary scientific driver is weak gravitational lensing, but the survey is...
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...
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...
SPRINGER JOURNALS IN ECONOMICS (2001)
New York, Steinkopff Darmstadt, Get This, Weeks Faster, T. Ihori, M. J. Keen, ...
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The Luminosity Function of the Coma Cluster Core for -25 (1995)
Bernstein, G. M., Nichol, R. C., Tyson, J. A., Ulmer, M. P., Wittman, D.
We determine the luminosity function (LF) of galaxies in the core of the Coma cluster for M_R
ADAPTIVE OPTICS EXPERIMENTS USING SODIUM LASER GUIDE STARS M. Lloyd-Hart (1995)
Angel Jacobsen Wittman, M. Lloyd-hart, B. Jacobsen, D. Wittman, R. Dekany, ...
The Multiple Mirror Telescope (MMT) has been used in experiments with sodium laser guide stars to sense and correct atmospheric image distortion. The major goal was to develop and test concepts for a...
ADAPTIVE OPTICS EXPERIMENTS USING SODIUM LASER GUIDE STARS M. Lloyd-Hart (1995)
Angel Jacobsen, D. Wittman, R. Dekany, D. Mccarthy, J. Beletic
The Multiple Mirror Telescope (MMT) has been used in experiments with sodium laser guide stars to sense and correct atmospheric image distortion. The major goal was to develop and test concepts for a...
Direct 75 Milliarcsecond Images from the Multiple Mirror Telescope with Adaptive Optics (1993)
M. Lloyd-hart, R. Dekany, B. Mcleod, D. Wittman, D. Colucci, ...
We report results from an adaptive optics system designed to provide imaging at the diffraction limit of resolution in the near infrared at the Multiple Mirror Telescope (MMT). For the present...
Direct 75 Milliarcsecond Images from the Multiple Mirror Telescope with Adaptive Optics (1993)
M. Lloyd-hart, Lloyd-Hart Dekany, B. Mcleod, D. Wittman, D. Colucci, D. Mccarthy, ...
We report results from an adaptive optics system designed to provide imaging at the diffraction limit of resolution in the near infrared at the Multiple Mirror Telescope (MMT). For the present...