n e Grid2003 Project has deployed a multi-virfual organization, application-driven grid laboratory ('"Grid3'7 that has sustained for several months the production-level services required by physics experiments of the Large Hadron Collider at CERN (ATLAS and CMS), the Sloan Digital Sky Survey project, the gravitational wave search experiment LIGO, the BTeV mperiment at Fermilab, as well as applications in molecular structure analysis and genome analysis, and computer science research projects in such areas as job and data scheduling. The deployed infiastmcture has been operating since Noisniber 2003 with 27 sites, apeak of 2800 processors, work loads fiom 10 different applications exceeding 1300 simultaneous jobs, and data transfers among sites of greater than 2 TBiday. We describe the principles that have guided the development of this unique infrastructure and the practical experiences that have resultedfiom its creation and use. We discuss application requirements for grid services deployment and con$guration. monitoring infiastnic fure, application performance, metrics. and operational experiences. We also summarize lessons learned.

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Sky coverage is one of the most important pieces of information about astronomical observations. We discuss possible representations, and present algorithms to create and manipulate shapes consisting of generalized spherical polygons with arbitrary complexity and size on the celestial sphere. This shape specification integrates well with our Hierarchical Triangular Mesh indexing toolbox, whose performance and capabilities are enhanced by the advanced features presented here. Our portable implementation of the relevant spherical geometry routines comes with wrapper functions for database queries, which are currently being used within several scientific catalog archives including the Sloan Digital Sky Survey, the Galaxy Evolution Explorer and the Hubble Legacy Archive projects as well as the Footprint Service of the Virtual Observatory.

Most databases for spherically distributed data are not structured in a manner consistent with their geometry. As a result, such databases possess undesirable artifacts, including the introduction of "tears" in the data when they are mapped onto a flat file system. Furthermore, it is difficult to make queries about the topological relationship among the data components without performing real arithmetic. Therefore, a new representation for spherical data is introduced called the sphere quadree, which is based on the recursive subdivision of spherical triangles obtained by projecting the faces of an icosahedron onto a sphere. Sphere quadtrees allow the representation of data at multiple levels and arbitrary resolution. For actual data, such a hierarchical data structure provides the ability to correlate geographic data by providing a consistent reference among data sets of different resolutions or data that are not geographically registered. Furthermore, efficient search strategies can be easily implemented for the selection of data to be rendered or analyzed by a specific technique. In addition, sphere quadtrees offer significant potential for improving the accuracy and efficiency of spherical surface rendering algorithms as well as for spatial data management and geographic information systems.

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