The Century Survey: A Deeper Slice of the Universe

The Century Survey (CS hereafter) is a complete redshift survey of a 1° wide strip. It covers 0.03 steradians to a limiting mR = 16.13. The survey is 98.4% complete and contains 1762 galaxies. Large-scale features in the survey are qualitatively similar to those in other surveys: there are large voids surrounded or nearly surrounded by thin dense regions which are sections of structures like (and including) the Great Wall. The survey crosses the classical Corona Borealis supercluster. The galaxy density enhancement associated with this system extends for \u3c˜100h-1 Mpc-1 (the Hubble constant is H0 = 100h km s-1 Mpc -1) The Schechter (1976, ApJ, 203, 297) luminosity function parameters for the CS are: Mc*Sub = - 20.73+0.17 over -0.18, αcs=-1.17 +o.19 over -0.19, and φ*cs = 0.0250±0.0061 Mpc-3 mag-1 . In concert with the ESO Key Program (Vettolani et al. 1997, A&A;, 325, 954; Zucca et al. 1997, A&A;, 326, 477) and the AUTOFIB (Ellis et al. 1996, MNRAS, 280, 235) surveys, the CS indicates that the absolute normalization of the luminosity function exceeds estimates based on shallower and/or sparser surveys

Uncertainty propagation in the Model Web: A case study with e-Habitat

e-Habitat is a Web Processing Service (WPS) designed to compute the likelihood of finding ecosystems with equal properties. Inputs to the WPS, typically thematic geospatial ¿layers¿, can be discovered using standardised catalogues, and the outputs tailored to specific end user needs. Because these layers can range from geophysical data captured through remote sensing to socio-economical indicators, e-Habitat is exposed to a broad range of different types and levels of uncertainties. Potentially chained to other services to perform ecological forecasting for example, e-Habitat would be an additional component further propagating uncertainties from a potentially long chain of model services. This integration of complex resources increases the challenges in dealing with uncertainty. For such a system, as envisaged by initiatives such as the Group on Earth Observation¿s ¿Model Web¿, to be used for policy or decision making, users must be provided with information on the quality of the outputs since all system components will be subject to uncertainty. UncertWeb will create the Uncertainty enabled Model Web by promoting interoperability between data and models with quantified uncertainty, building on existing open, international standards. UncertWeb will thus develop open source implementations of encoding standards, service interface profiles, discovery and chaining mechanisms, and generic tools to realize a "Model Web" taking uncertainty in data and models into account. It is the objective of this paper to discuss the main types of uncertainties e-Habitat has to deal with and to present the benefits of the use of the UncertWeb framework.JRC.H.3-Global environement monitorin

Redshifts for 2410 Galaxies in the Century Survey Region

The `Century Survey' strip covers 102 square degrees within the limits 8.5h \leq \alpha_{1950} \leq 16.5h, 29.0 degrees \leq \delta_{1950} \leq 30.0 degrees. The strip passes through the Corona Borealis supercluster and the outer region of the Coma cluster. Within the Century Survey region, we have measured 2410 redshifts which constitute four overlapping complete redshift surveys: (1) 1728 galaxies with Kron-Cousins R_{phot} \leq 16.13 covering the entire strip, (2) 507 galaxies with R_{phot} \leq 16.4 in the right ascension range 8h 32m \leq \alpha_{1950} \leq 10h 45m, (3) 1251 galaxies with absorption- and K-corrected R_{CCD, corr} \leq 16.2 covering the right ascension range 8.5h \leq \alpha_{1950} \leq 13.5h and (4) 1255 galaxies with absorption- and K-corrected V_{CCD, corr} \leq 16.7 also covering the right ascension range 8.5h \leq \alpha_{1950} \leq 13.5h. All of these redshift samples are more than 98 % complete to the specified magnitude limit.Comment: 18 pages, 9 figures, 3 tables, 2 abbreviated tables. In press, to appear in Astronomical Journal, Dec. 2001 issu

An Optical and X-Ray Study of Abell 576, a Galaxy Cluster with a Cold Core

We analyze the galaxy population and dynamics of the galaxy cluster A576; the observational constraints include 281 redshifts (230 new), R- band CCD galaxy photometry over a 2 h^-1^ Mpc x 2 h^-1^ Mpc region centered on the cluster, an Einstein IPC X-ray image, and an Einstein MPC X-ray spectrum. We focus on an 86% complete magnitude-limited sample (R_23.5_ \u3c 17) of 169 cluster galaxies. The cluster galaxies with emission lines in their spectra have a larger velocity dispersion and are significantly less clustered on this 2 h^-1^ Mpc scale than galaxies without emission lines. We show that excluding the emission-line galaxies from the cluster sample decreases the velocity dispersion by 18% and the virial mass estimate by a factor of 2. The central cluster region contains a nonemission galaxy population and an intracluster medium which is significantly cooler (σ_core_ = 387_-105_^+250^ km s^-1^ and T_x_ = 1.6_-0.3_^+0.4^ keV at 90% confidence) than the global populations (σ = 977_-96_^+124^ km s^- 1^ for the nonemission population and T_X_ \u3e 4 keV at 90% confidence). Because (1) the low-dispersion galaxy population is no more luminous than the global population and (2) the evidence for a cooling flow is weak, we suggest that the core of A576 may contain the remnants of a lower mass subcluster. We examine the cluster mass, baryon fraction, and luminosity function. The cluster virial mass varies significantly depending on the galaxy sample used. Consistency between the hydrostatic and virial estimators can be achieved if (1) the gas temperature at r~1 h^-1^ Mpc is T_X_ ~ 8 keV (the best-fit value) and (2) several velocity outliers are excluded from the virial calculation. Although the best-fit Schechter function parameters and the ratio of galaxy to gas mass in A576 are typical of other clusters, the baryon fraction is relatively low. Using the consistent cluster binding mass, we show that the gas mass fraction is ~3 h^-3/2^% and the baryon fraction is ~6%

ASTER, a multinational Earth observing concept

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a facility instrument selected for launch in 1998 on the first in a series of spacecraft for NASA's Earth Observing System (EOS). The ASTER instrument is being sponsored and built in Japan. It is a three telescope, high spatial resolution imaging instrument with 15 spectral bands covering the visible through to the thermal infrared. It will play a significant role within EOS providing geological, biological, land hydrological information necessary for intense study of the Earth. The operational capabilities for ASTER, including the necessary interfaces and operational collaborations between the US and Japanese participants, are under development. EOS operations are the responsibility of the EOS Project at NASA's Goddard Space Flight Center (GSFC). Although the primary EOS control center is at GSFC, the ASTER control facility will be in Japan. Other aspects of ASTER are discussed

eHabitat: A Contribution to the Model Web for Habitat Assessments and Ecological Forecasting

In striving to improve the predictive capabilities of ecological forecasting we face three basic choices ¿ develop new models, improve existing ones or increase the connectivity of models so they can work together. The latter approach of chaining different interoperable models is of particular interest, as technical developments have made it increasingly viable to combine models that can answer more questions than the individual models alone, allowing users to address complex questions, often of a multi-disciplinary nature. This concept of a Model Web encourages the setting up of a dynamic network of interoperating models, communicating with each other using standardized web services. It is the purpose of this paper to introduce the potential contribution of e-Habitat to the Model Web. e-Habitat is conceived as a Web Processing Service for computing the likelihood of finding ecosystems with equal properties. By developing e-Habitat according to Model Web principles, end-users can define the thematic layers for input to the model from various sources. These input layers are discovered using standards-based catalogues, which are a fundamental component of Model Web and generic Spatial Data Infrastructures. e-Habitat integrates data ranging from remote sensing data to socio-economical indicators, thus offering a huge potential for multi-disciplinary modelling. We will show that e-Habitat can be used for the identification of habitats that are most vulnerable or of the optimal locations for monitoring stations or, when coupled with climate change model services, for ecological forecasting. As such, it is an excellent example of the Model Web in practice.JRC.H.3-Global environement monitorin

Climate change\u27s impact on key ecosystem services and the human well-being they support in the US

Climate change alters the functions of ecological systems. As a result, the provision of ecosystem services and the well-being of people that rely on these services are being modified. Climate models portend continued warming and more frequent extreme weather events across the US. Such weather-related disturbances will place a premium on the ecosystem services that people rely on. We discuss some of the observed and anticipated impacts of climate change on ecosystem service provision and livelihoods in the US. We also highlight promising adaptive measures. The challenge will be choosing which adaptive strategies to implement, given limited resources and time. We suggest using dynamic balance sheets or accounts of natural capital and natural assets to prioritize and evaluate national and regional adaptation strategies that involve ecosystem services. © The Ecological Society of America

Addressing the need for improved land cover map products for policy support

The continued increase of anthropogenic pressure on the Earth’s ecosystems is degrading the natural environment and then decreasing the services it provides to humans. The type, quantity, and quality of many of those services are directly connected to land cover, yet competing demands for land continue to drive rapid land cover change, affecting ecosystem services. Accurate and updated land cover information is thus more important than ever, however, despite its importance, the needs of many users remain only partially attended. A key underlying reason for this is that user needs vary widely, since most current products – and there are many available – are produced for a specific type of end user, for example the climate modelling community. With this in mind we focus on the need for flexible, automated processing approaches that support on-demand, customized land cover products at various scales. Although land cover processing systems are gradually evolving in this direction there is much more to do and several important challenges must be addressed, including high quality reference data for training and validation and even better access to satellite data. Here, we 1) present a generic system architecture that we suggest land cover production systems evolve towards, 2) discuss the challenges involved, and 3) propose a step forward. Flexible systems that can generate on-demand products that match users’ specific needs would fundamentally change the relationship between users and land cover products – requiring more government support to make these systems a reality

A Photometric and Kinematic Study of AWM 7

We have measured redshifts and Kron-Cousins R-band magnitudes for a sample of galaxies in the poor cluster AWM 7. We have measured redshifts for 172 galaxies; 106 of these are cluster members. We determine the luminosity function from a photometric survey of the central 1.2 h^{-1} x 1.2 h^{-1} Mpc. The LF has a bump at the bright end and a faint-end slope of \alpha = -1.37+-0.16, populated almost exclusively by absorption-line galaxies. The cluster velocity dispersion is lower in the core (\sim 530 km/s) than at the outskirts (\sim 680 km/s), consistent with the cooling flow seen in the X-ray. The cold core extends \sim 150 h^{-1} kpc from the cluster center. The Kron-Cousins R-band mass-to-light ratio of the system is 650+-170 h M_\odot/L_\odot, substantially lower than previous optical determinations, but consistent with most previous X-ray determinations. We adopt H_0 = 100 h km/s/Mpc throughout this paper; at the mean cluster redshift, (5247+-76 km/s), 1 h^{-1} Mpc subtends 65\farcm5.Comment: 37 pages, LaTeX, including 12 Figures and 1 Table. Accepted for publication in the Astronomical Journa