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Session 55 - New Digital Sky Surveys.
Display session, Wednesday, June 10
The Catalogs and Surveys Branch of the Space Telescope Science Institute, in collaboration with a number of other institutions, is constructing an all-sky catalog of astronomical objects to support the operations of current and future ground and space based telescopes. It is being generated from the application of image processing and object recognition techniques to digitized photographs taken from the Palomar and UK Schmidt survey telescopes. To accurately calibrate these data, it is crucial that we be able to support cross-references between the internal observations and to other external astronomical databases. This database is expected to contain about 15 billion measurements of 2 billion individual stars and galaxies, and will be about 4TB in size.
For efficient access to objects, we have partitioned the sky into 32768 equal-area spatial regions, each of which is the leaf node of a Hierarchical Triangulated Mesh (HTM) Quad-Tree and is an Objectivity Database. Individual plate measurements and catalogues are stored as containers within each database, along with a master index container which is used to provide low-overhead links between object measurements and external references.
We have currently constructed the individual databases for our production system, and have already loaded the measurements from the first Guide-Star Catalogue, which was previously constructed to support the Hubble Space Telescope. Additional measurements are now being loaded into this federated database and we expect to complete catalogue construction and calibration over the next 2-3 years.
We also give an overview of the planned capabilities of the database to allow the exchange of information between this and other external distributed databases such as the SDSS or 2MASS who plan on adopting the same sky partitioning scheme. This will allow for efficient cross-identification of objects from different databases and will provide a powerful tool for future researchers.
Program listing for Wednesday