On The Nature of Fossil Galaxy Groups (2009)
La Barbera, F., De Carvalho, R. R., De La Rosa, I. G., Sorrentino, G., Gal, R. R., Kohl-Moreira, J. L.
We present a new sample of 25 fossil groups (FGs) at z < 0.1, along with a control sample of seventeen bright ellipticals located in non-fossil systems. Both the global properties of FGs (e.g. X-ray...
Lemaux, B. C., Lubin, L. M., Sawicki, M., Martin, C., Lagattuta, D. J., Gal, R. R., ...
We present results of a spectroscopic search for Lyα emitters (LAEs) in the Cl1604 supercluster field using the extensive spectroscopic Keck/DEep Imaging Multi-Object Spectrograph database taken as...
Lubin, L. M., Gal, R. R., Lemaux, B. C., Kocevski, D. D., Squires, G. K.
We present the Observations of Redshift Evolution in Large-Scale Environments (ORELSE) Survey, a systematic search for structure on scales greater than 10 h^(–1)_70 Mpc around 20 well-known...
The Northern Sky Optical Cluster Survey. III. A Cluster Catalog Covering PI Steradians (2009)
Gal, R. R., Lopes, P. A. A., De Carvalho, R. R., Kohl-Moreira, J. L., Capelato, H. V., Djorgovski, S. G.
We present the complete galaxy cluster catalog from the Northern Sky Optical Cluster Survey, a new, objectively defined catalog of candidate galaxy clusters at z ≾ 0.25 drawn from the Digitized...
On the Nature of Fossil Galaxy Groups: Are they really fossils ? (2008)
La Barbera, F., De Carvalho, R. R., De La Rosa, I. G., Sorrentino, G., Gal, R. R., Kohl-Moreira, J. L.
We use SDSS-DR4 photometric and spectroscopic data out to redshift z~0.1 combined with ROSAT All Sky Survey X-ray data to produce a sample of twenty-five fossil groups (FGs), defined as bound systems...
The Northern Sky Optical Cluster Survey III: A Cluster Catalog Covering Pi Steradians (2008)
Gal, R. R., Lopes, P. A. A., De Carvalho, R. R., Kohl-Moreira, J. L., Capelato, H. V., Djorgovski, S. G.
We present the complete galaxy cluster catalog from the Northern Sky Optical Cluster Survey, a new, objectively defined catalog of candidate galaxy clusters at z
Lubin, L. M., Gal, R. R., Lemaux, B. C., Kocevski, D. D., Squires, G. K.
We present the Observations of Redshift Evolution in Large Scale Environments (ORELSE) survey, a systematic search for structure on scales greater than 10 Mpc around 20 well-known clusters at 0.6 < z...
The Complex Structure of the Cl 1604 Supercluster at z ~ 0.9 (2008)
Gal, R. R., Lemaux, B. C., Lubin, L. M., Kocevski, D., Squires, G. K.
The Cl 1604 supercluster at z = 0.9 is one of a small handful of such structures discovered in the high-redshift universe and is the first target observed as part of the Observations of Redshift...
2DPHOT: A Multi-purpose Environment for the Two-dimensional Analysis of Wide-field Images (2008)
La Barbera, F., De Carvalho, R. R., Kohl-Moreira, J. L., Gal, R. R., Soares-Santos, M., Capaccioli, M., ...
We describe 2DPHOT, a general purpose analysis environment for source detection and analysis in deep wide-field images. 2DPHOT is an automated tool to obtain both integrated and surface photometry of...
The Complex Structure of the Cl 1604 Supercluster at z~0.9 (2008)
Gal, R. R., Lemaux, B. C., Lubin, L. M., Kocevski, D., Squires, G. K.
The Cl1604 supercluster at z=0.9 is one of a small handful of such structures discovered in the high redshift universe, and is the first target observed as part of the Observations of Redshift...
S. G. Djorgovski, M. Pahre, R. R. Gal, A. Gray, J. Roden
The subjective nature of the Abell catalog has been widely recognized as its major limitation. We report on the preliminary results of an effort to create an unbiased catalog of clusters of galaxies...
Lopes, P. A. A., De Carvalho, R. R., Capelato, H. V., Gal, R. R., Djorgovski, S. G., Brunner, R. J., ...
We present a comparison of optical and X-ray properties of galaxy clusters in the northern sky. We determine the recovery rate of X-ray detected clusters in the optical as a function of richness,...
Fassnacht, C. D., Gal, R. R., Lubin, L. M., McKean, J. P., Squires, G. K., Readhead, A. C. S.
We report the discovery of four groups of galaxies along the line of sight to the B1608+656 gravitational lens system. One group is at the redshift of the primary lensing galaxy (z = 0.631) and...
Bloom, J. S., Prochaska, J. X., Pooley, D., Blake, C. H., Foley, R. J., Jha, S., ...
The localization of the short-duration, hard-spectrum GRB 050509b was a watershed event. Thanks to the nearly immediate relay of the GRB position by Swift, we began imaging the GRB field 8 minutes...
A Catalog of Distant Compact Groups Using DPOSS (2005)
De Carvalho, R. R., Goncalves, T. S., Iovino, A., Kohl-Moreira, J. L., Gal, R. R., Djorgovski, S. G.
In this paper we present an objectively defined catalog of 459 small, high density groups of galaxies out to z~0.2 in a region of 6260 square degrees in the northern sky derived from the Digitized...
Morphology of low-redshift compact galaxy clusters I. Shapes and radial profiles (2005)
Strazzullo, V., Paolillo, M., Longo, G., Puddu, E., Djorgovski, S. G., De Carvalho, R. R., ...
The morphology of clusters of galaxies may be described with a set of parameters which contain information about the formation and evolutionary history of these systems. In this paper we present a...
Pushing the Boundaries of the Cl 1604 Supercluster at z~0.9 (2004)
Gal, R. R., Lubin, L. M., Squires, G. K.
The Cl 1604 supercluster at z~0.9 is known to contain at least four distinct member clusters, separated in both projection and redshift. In this paper we present deep, multicolor wide-field imaging...
Massive Star Populations in Wolf-Rayet Galaxies (2004)
Fernandes, I. F., De Carvalho, R., Contini, T., Gal, R. R.
We analyze longslit spectral observations of fourteen Wolf-Rayet galaxies from the sample of Schaerer, Contini & Pindao (1999). All 14 galaxies show broad Wolf-Rayet emission in the blue region of...
Lopes, P. A. A., De Carvalho, R. R., Gal, R. R., Djorgovski, S. G., Odewahn, S. C., Mahabal, A. A., ...
We present an optically selected galaxy cluster catalog from ~ 2,700 square degrees of the Digitized Second Palomar Observatory Sky Survey (DPOSS), spanning the redshift range 0.1 < z < 0.5,...
Spectroscopic Confirmation of the Cl 1604 Supercluster at z~0.9 (2004)
We present spectroscopic confirmation of the Cl 1604 supercluster at z~0.9. Originally detected as two individual clusters, Cl 1604+4304 at z = 0.90 and Cl 1604+4321 at z = 0.92, which are closely...
Peculiar Broad Absorption Line Quasars found in DPOSS (2003)
Brunner, Robert J., Hall, Patrick B., Djorgovski, S. George, Gal, R. R., Mahabal, A. A., Lopes, P. A. A., ...
With the recent release of large (i.e., > hundred million objects), well-calibrated photometric surveys, such as DPOSS, 2MASS, and SDSS, spectroscopic identification of important targets is no longer...
The Multiplicity Function of Galaxies (2003)
Puddu, E., De Filippis, E., Longo, G., Andreon, S., Gal, R. R.
The multiplicity function (MF) of groups and clusters of galaxies is determined using galaxy catalogues extracted from a set of Digitized Palomar Sky Survey (DPOSS) plates. The two different types of...
Gal, R. R., De Carvalho, R. R., Lopes, P. A. A., Djorgovski, S. G., Brunner, R. J., Mahabal, A. A., ...
We present a new, objectively defined catalog of candidate galaxy clusters based on the galaxy catalogs from the Digitized Second Palomar Observatory Sky Survey (DPOSS). This cluster catalog, derived...
THE DIGITIZED SECOND PALOMAR OBSERVATORY SKY SURVEY (DPOSS). III. STAR-GALAXY SEPARATION (2003)
S. C. Odewahn, R. R. Gal, S. G. Djorgovski, R. Brunner, A. Mahabal, ...
We discuss object classification for a multicolor survey of high-latitude fields from the Digitized Second Palomar Observatory Sky Survey (DPOSS) and the resulting Palomar-Norris Sky Catalog. Two...
The Digitized Second Palomar Observatory Sky Survey (DPOSS) II: Photometric Calibration (2002)
Gal, R. R., De Carvalho, R. R., Odewahn, S. C., Djorgovski, S. G., Mahabal, A. A., Brunner, R. J., ...
We present the photometric calibration technique for the Digitized Second Palomar Observatory Sky Survey (DPOSS), used to create seamless catalogs of calibrated objects over large sky areas. After...
Exploration of Large Digital Sky Surveys (2000)
Djorgovski, S. G., Brunner, R. J., Mahabal, A. A., Odewahn, S. C., De Carvalho, R. R., Gal, R. R., ...
We review some of the scientific opportunities and technical challenges posed by the exploration of the large digital sky surveys, in the context of a Virtual Observatory (VO). The VO paradigm will...
Searches for Rare and New Types of Objects (2000)
Djorgovski, S. G., Mahabal, A. A., Brunner, R. J., Gal, R. R., Castro, S., De Carvalho, R. R., ...
Systematic exploration of the observable parameter space, covered by large digital sky surveys spanning a range of wavelengths, will be one of the primary modes of research with a Virtual Observatory...
Luminosity function of clusters of galaxies (2000)
Paolillo, M., Andreon, S., Longo, G., Puddu, E., Gal, R. R., Scaramella, R., ...
The composite galaxy luminosity function (hereafter LF) of 39 Abell clusters of galaxies is derived by computing the statistical excess of galaxy counts in the cluster direction with respect to...
Margoniner, V. E., De Carvalho, R. R., Gal, R. R., Djorgovski, S. G.
We examine the Butcher-Oemler effect and its cluster richness dependence in the largest sample studied to date: 295 Abell clusters. We find a strong correlation between cluster richness and the...
Exploring the Multi-Wavelength, Low Surface Brightness Universe (2000)
Brunner, R. J., Djorgovski, S. G., Gal, R. R., Mahabal, A. A., Odewahn, S. C.
Our current understanding of the low surface brightness universe is quite incomplete, not only in the optical, but also in other wavelength regimes. As a demonstration of the type of science which is...
Mass-to-Light Ratios of Groups and Clusters of Galaxies (2000)
Hradecky, V., Jones, C., Donnelly, R. H., Djorgovski, S. G., Gal, R. R., Odewahn, S. C.
We constrain the mass-to-light ratios, gas mass fractions, baryon mass fractions and the ratios of total to luminous mass for a sample of eight nearby relaxed galaxy groups and clusters: A262, A426,...
The Palomar Abell Cluster Optical Survey I: Photometric Redshifts for 431 Abell Clusters (2000)
Gal, R. R., De Carvalho, R. R, Brunner, R., Odewahn, S. C., Djorgovski, S. G.
This paper presents photometric redshifts for 431 Abell clusters imaged as part of the Palomar Abell Cluster Optical Survey (PACOS), of which 236 are new redshi fts. We have obtained moderately deep,...
The Northern Sky Optical Cluster Survey I: Detection of Galaxy Clusters in DPOSS (1999)
Gal, R. R., DeCarvalho, R. R., Odewahn, S. C., Djorgovski, S. G., Margoniner, V. E.
The Northern Sky Optical Cluster Survey is a project to create an objective catalog of galaxy clusters over the entire high-galactic-latitude Northern sky, with well understood selection criteria. We...
The Radio Afterglow and the Host Galaxy of the X-Ray Rich GRB 981226 (1999)
Frail, D. A., Kulkarni, S. R., Bloom, J. S., Djorgovski, S. G., Gorjian, V., Gal, R. R., ...
We report the discovery of a radio transient VLA 232937.2-235553, coincident with the proposed X-ray afterglow for the gamma-ray burst GRB 981226. This GRB has the highest ratio of X-ray to gamma-ray...
The Luminosity Function of 24 Abell Clusters from the CRoNaRio catalogues (1999)
Paolillo, M., Andreon, S., Longo, G., Puddu, E., Piranomonte, S., Scaramella, R., ...
We present the composite luminosity function of galaxies for 24 Abell clusters studied in our survey of the Northern Hemisphere, using DPOSS data in the framework of the CRoNaRio collaboration. Our...
An automatic procedure to extract galaxy clusters from CRoNaRio catalogs (1999)
Puddu, E., Andreon, S., Longo, G., Paolillo, M., Scaramella, R., Testa, V., ...
We present preliminary results of a simple peak finding algorithm applied to catalogues of galaxies, extracted from the Second Palomar Sky Survey in the framework of the CRoNaRio project. All...
Quasar-Marked Protoclusters and Biased Galaxy Formation (1999)
Djorgovski, S. G., Odewahn, S. C., Gal, R. R., Brunner, R., De Carvalho, R. R.
We report on the current status of our search for protoclusters around quasars at z > 4. While the search is still very incomplete, clustered companion galaxies are found in virtually every case...
Photometric Redshifts for DPOSS Galaxy Clusters at z (1999)
Gal, R. R., Odewahn, S. C., Djorgovski, S. G., Brunner, R., DeCarvalho, R. R.
We report on the creation of an unbiased catalog of galaxy clusters from the galaxy catalogs derived from the digitized POSS-II (DPOSS). Utilizing the g-r color information, we show that it is...
The afterglow, the redshift, and the extreme energetics of the gamma-ray burst 990123 (1999)
Kulkarni, S. R., Djorgovski, S. G., Odewahn, S. C., Bloom, J. S., Gal, R. R., Koresko, C. D., ...
Afterglow, or long-lived emission, has now been detected from about a dozen well-positioned gamma-ray bursts. Distance determinations made by measuring optical emission lines from the host galaxy, or...
The Host Galaxy of GRB 990123 (1999)
Bloom, J. S., Odewahn, S. C., Djorgovski, S. G., Koresko, C., Neugebauer, G., ...
We present deep images of the field of gamma-ray burst (GRB) 990123 obtained in a broad-band UV/visible bandpass with the Hubble Space Telescope, and deep near-infrared images obtained with the...
The Palomar Digital Sky Survey (DPOSS) (1998)
Djorgovski, S. G., Gal, R. R., Odewahn, S. C., De Carvalho, R. R., Brunner, R., Longo, G., ...
We describe DPOSS, a new digital survey of the northern sky, based on the POSS-II photographic sky atlas. The survey covers the entire sky north of delta = -3 deg in 3 bands, calibrated to the Gunn...
Data-Mining a Large Digital Sky Survey: From the Challenges to the Scientific Results (1997)
Djorgovski, S. G., De Carvalho, R. R., Odewahn, S. C., Gal, R. R., Roden, J., Stolorz, P., ...
The analysis and an efficient scientific exploration of the Digital Palomar Observatory Sky Survey (DPOSS) represents a major technical challenge. The input data set consists of 3 Terabytes of pixel...
Cataloging of the Digitized POSS-II, and Some Initial Scientific Results From It (1996)
Djorgovski, S. G., De Carvalho, R. R., Gal, R. R., Pahre, M. A., Scaramella, R., Longo, G.
We are conducting an effort to catalog all sources detected in the digitized POSS-II (DPOSS). This is now becoming an international collaboration including Caltech and the Observatories of Rome and...