ADASS XII Conference

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VO/Archives

P1.1 Metadata for the VO: the Case of UCDs

Sebastien Derriere, Francois Ochsenbein, Thomas Boch (CDS - Observatoire de Strasbourg)

The UCDs (Unified Content Descriptors) were first developed in the ESO/CDS data mining project, to describe precisely the contents of the individual fields (columns) of tables available from a data center. They have been used to describe the content of the 105 columns available in the different VizieR tables.

Owing to the wide diversity and high heterogeneity of table contents, UCDs constitute an excellent starting point for a hierarchical description of astronomy, for general data mining purposes.

We present different applications of UCDs: selection of catalogues, based on their content; identification of catalogues having similar fields; automated data conversion allowing direct comparison of data in cross-identifications. The compatibility of UCDs with semantic descriptions developed in other contexts (data models for space-time coordinates or image datasets) will also be addressed.

P1.2 Russian and fSU Resources to be Integrated in the IVO

A. Kilpio, O. Dluzhnevskaya, E. Kilpio, D. Kovaleva, O. Malkov

The first collection of many Russian and fSU resources of astronomical data accumulated in Russian observatories and institutions has been compiled. As a first step we plan to provide a transparent access to these resources for scientific and educational purposes in the frame of the Russian Virtual Observatory (RVO) project. The collection of the astronomical resources is updated constantly. We evaluate the quality of the resources, in particular, by conducting the expert analysis. Another important goal of the RVO project is to elaborate the method of information representation based on well-known and accepted standards, as well as to provide the new ones.

The Russian Centre for Astronomical Data (CAD) staff will carry out the activities on construction of the information hub of the Russian Virtual Observatory and on integration Russian and fSU resources in the International Virtual Observatory. CAD is one of the general purpose data centers for astronomy world-wide. CAD has been systematically collecting and distributing astronomical data for more than 20 years.

P1.3 The MAST Pointings Tables Project

K. Levay, P. Padovani, R. Thompson, M. Donahue, M. Corbin (STScI)

We have undertaken a project to create a database of all HST imaging observations organized by position on the sky. A web-based interface to this database has also been created, in supplement to the existing interface to the HST archive. These "pointings tables" enable quick identification of overlapping fields that can be used for multiwavelength studies of objects, and for variability studies by comparing images at a given pointing over different epochs. They will also allow for "minisurveys" by providing lists of images over a specified coordinate range, such as above and below the Galactic plane. We plan to develop pointings tables for other MAST missions besides HST, and expect these tables to form an important part of upcoming virtual observatories.

P1.4 Towards an AVO Interoperability Prototype.

Mark G. Allen, F. Genova, F. Ochsenbein, S. Derriere, C. Arviset, P. Didelon, S. Garrington, R. Mann, A. Micol, A. Richards, G. Rixon, A. Wicenec, M. Dolensky

As part of the Astrophysical Virtual Observatory (AVO) we are developing an interoperability prototype which aims to federate a set of astronomical archives, representative of a variety of techniques (space/ground, images/spectra, X-ray to Radio wavelengths) into the CDS VizieR and Aladin tools. The target archives for federation are: VLT, NTT, EIS (ESO), HST/ECF, ISO, XMM (ESA), Wide field UK archives, MERLIN, and Terapix. We demonstrate the interoperability of these federated archives with science examples using multiwavelength image data and catalog overlays, and highlight new functionalities of the federation and integration tools.

P1.5 The AXAF (Chandra) Guide and Acquisition Star Catalog V1.5 (AGASC 1.5)

Dennis Schmidt, Paul Green (SAO)

Chandra's Aspect Camera Assembly (ACA) measures positions of selected stars to acquire and hold target pointings, and for post facto aspect determination. The selection and matching of the guide stars is governed by data in the AXAF (Chandra) Guide and Acquisition Star Catalog (AGASC). Based originally on version 1.1 of the Guide Star Catalog for the Hubble Space Telescope, the AGASC has been extended and refined in several stages, with data from additional catalogs and with recalibrations based on experience with Chandra.

In 2002 the Chandra X-ray Center (CXC) completed a major upgrade of the AGASC. We merged data from three catalogs -- Tycho-2, GSC-ACT, and 2MASS. The Tycho-2 data substantially improve the photometric and astrometric measurements of stars as faint as V=12, while the GSC-ACT merge decreases by about half the systematic astrometric errors down to the catalog limit of about V=14.5. The 2MASS data identify galaxies down to J=12.5. These new catalog data enhance the value of the AGASC for scientific as well as operational purposes.

Specifically for Chandra's use of the AGASC, we recalibrated the estimated ACA magnitudes based on Chandra on-orbit measurements, and implemented a more sophisticated calculation of the effect of nearby stars on the best-fit centroid of a guide star.

In the process of the upgrade, we encountered and corrected a variety of errors introduced in earlier merges from published source catalogs.

This paper presents the rationale for and the process of making each of the changes. It then discusses the improvements in performance that we expect to result.

This project is supported by the Chandra X-ray Center under NASA contract NAS8-39073.

P1.6 SkyDOT: A Publicly Accessible Variability Database, Containing Multiple Sky Surveys and Real-Time Data.

Dan Starr, Przemek Wozniak, W. Thomas Vestrand, Robert White (LANL)

The Sky Database for Objects in Time-Domain (SkyDOT) is a virtual observatory which allows general access to several massive variability surveys. Although initially intended publicly release the data from Los Alamos's RAPTOR project, this database now includes data sets from both OGLE II and ROTSE I. SkyDOT's emphasis on time derivative data is enhanced by its update with real-time RAPTOR data. This enables user access to the most recent measurements of a given object, as well as its variability history.

Our main task has been to construct an efficient relational database containing all existing data, while also handling a real-time influx of data. We provide useful web tools, which allow easy access to both astronomers and the public. In our implementation we employ a PostgreSQL database with a PHP based web interface. This server will initially allow common searches, specific queries, and access to light curves. In the future we will include: machine learning classification tools and access to spectral information.

P1.7 OASIS: A Data Fusion System Optimized for Access to Distributed Archives

J.C. Good, Mih-seh Kong, G.B. Berriman

The On-Line Archive Science Information Services (OASIS) client is accessible as a JAVA applet / JAR file through the NASA/IPAC Infrared Science Archive home page. It uses Geographical Information System (GIS) technology to provide data fusion and interaction services for astronomers. These services include the ability to process and display arbitrarily large image files, and user-controlled contouring, overlay regeneration and multi-table/image interactions.

OASIS has been optimized for access to distributed archives and data sets. It provides a mechanism that enables access to OASIS from "third-party" services and data providers. That is, any data provider who creates a query form to an archive containing a collection of data (images, catalogs, spectra) can direct the result files from the query into OASIS. Similarly, data providers who serve links to datasets or remote services on a web page can access all of these data with one instance of OASIS. In this way any data or service provider is given access to the full suite of capabilities of OASIS. We illustrate the "third-party" access feature with two examples: queries to the high-energy image datasets accessible from GSFC SkyView, and links to data that are returned from a target-based query to the NASA Extragalactic Database (NED).

OASIS also includes a file-transfer manager that reports the status of multiple asynchronous data downloads from remote sources to the client machine. It is a prototype for a request management system that will ultimately control and manage compute-intensive jobs submitted through OASIS to computing grids, such as requests for large scale image mosaics and bulk statistical analysis.

P1.8 A Web-based Tool for SDSS and 2MASS Database Searches

Marci Hendrickson, Alan Uomoto, David Golimowski (JHU)

We have developed a website using HTML, PHP, Python, and MySQL that analyzes data from the Sloan Digital Sky Survey (SDSS) and the Two-Micron All-Sky Survey (2MASS). The goal of this project is to locate brown dwarf candidates in the SDSS database by looking at color cuts; however, this site could also be useful for other targeted searches of the two databases as well as being a prototype for easily implemented, customized searches of other large databases.

The site uses MySQL databases created from broad searches of SDSS and 2MASS data, retrieving specified information. The broad queries on the SDSS and 2MASS database servers are run weekly so observers have the most up-to-date information from which to select their observational candidates. Observers can look at detailed information about specific objects, including finding charts, images, and, when available, spectra. In addition, updates from previous observations can be added by any collaborators; this format makes observational collaboration simple. Observers can also restrict the database search, just before or during an observing run, to select objects of special interest.

P1.9 Storage Options for Large VO Archives - The SDSS DR1 Experience

Jan vandenBerg, Alex Szalay (JHU) Jim Gray (Microsoft BARC) Ani Thakar (JHU)

We report on our experiences with evaluating storage hardware and firmware options for the SDSS Data Release 1 (DR1) archive. The unprecedented size of this archive presents daunting challenges with respect to storage of multiple datasets and providing high availability and performance to a large user community. Not only are the datasets large and complex, but the need to maintain several versions simultaneously and ensure the I/O speeds necessary for efficient data mining means that we are always "pushing the envelope" in terms of the available storage hardware.

This is not meant to be an exhaustive thesis on the available options and technology for large archive storage. However, since we have spent considerable time in evaluating and choosing the storage options for DR1, we felt that the knowledge and insights that we have gained in the process will be useful to other groups that plan to publish or mirror large astronomical archives for the VO community in the near future.

P1.10 Digital Access to Aero- and Astrophotographic Archives

J.-P. De Cuyper

The aim of this test-bed project, initiated and financed by the Belgian Federal Government, is to acquire, within the coming 4 years, the necessary know-how, hardware and software in order to preserve the historic scientific information contained in aero- and astrophotographic archives; to provide user-friendly internet access to the catalogue and the (meta)data and to make the photographic information scientifically exploitable again through a high resolution digitisation technique. We are constructing a high accuracy scanner XY airbearing table with laser interferometer steering, giving submicrometer absolute positioning accuracy, in order to attain the limiting positional accuracy determined by the internal plate errors.

The archives concerned are the astrophotographic plate archive of the Royal Observatory of Belgium and the aerophotographic images of the National Geographic Institute and of the Royal Museum of Central Africa (Congo, Rwanda, Burundi). All contain photographs on glass plates as well as on film sheets.

The technique of first making an analogue copy on roll film, allowing unattended all time scanning, will be studied in detail, as well as the photochemical treatment of fungi and deteriorations, in order to determine the introduced geometric and radiometric deformations. A digital catalogue is generated in a ODBC database that is to be distributed on intranet and internet (html files, ActiveX objects, C++ and Javascript programmation).

P1.11 Construction of the Japanese Virtual Observatory (JVO)

Yoshihiko Mizumoto, Masatoshi Ohishi, Naoki Yasuda, Yuji Shirasaki, Masahiro Tanaka (NAOJ) Yoshifumi Masunaga (Ochanomizu Univ. and NAOJ) Ken Miura, Hirokuni Monzen, Kenji Kawarai, Yasuhide Ishihara, Yasushi Yamaguchi, Youji Yanaka (Fujitsu Ltd.)

The National Astronomical Observatory of Japan (NAOJ) has been operating several large astronomical facilities, such as the SUBARU telescope in Hawaii, the 45 m radio telescope and the Nobeyama Millimeter Array in Nobeyama, Japan, and plans to construct the Atacama Large Millimeter Array in Chile under close collaborations with astronomers in the US and the EU. Since January 2002, the NAOJ has been connected to the SuperSINET with 10 Gbps, and it has become possible to provide huge amount of observed multi-color data and analyses facilities to other astronomical institutions not only in Japan but in other countries through SuperSINET. Thus we have started the Japanese Virtual Observatory (JVO) project since April 2002 (see, http://jvo.nao.ac.jp/index-e.html). JVO utilizes the Grid technology to combine several remote computational facilities (observed databases in Hawaii and in several locations in Japan, servers for the data analyses, machines for data mining, etc.). We have completed to define the query language for the JVO, and have been designing on the deployment of JVO components (user interfaces, manager for virtual observations, execution modules to perform virtual observations, registries to resolve observation information, etc.). We plan to construct a JVO-prototype by the end of 2002.

P1.12 The NOAO Science Archive, Version 2.0

R. Seaman, N. Zarate, T. Lauer, P. Warner (NOAO)

The NOAO Science Archive (NSA) is a step toward building a comprehensive scientific archive of the optical and infrared data holdings of the National Optical Astronomy Observatory. The goals for the NSA are to:


The holdings of the NSA (http://archive.noao.edu) will be drawn from the NOAO Survey projects (http://www.noao.edu/gateway/surveys/programs.html) as well as from other coherent imaging or spectral, optical/IR reduced datasets that may be identified as candidates from NOAO or community facilities. Catalogs and other derived data products will be included in addition to images, spectra and the tools necessary to evaluate them. Synoptic, time-domain data is a special focus in anticipation of the needs of the LSST. The NSA team is working in coordination with other groups at NOAO who are focusing on data handling and data pipeline systems.

Planning for the NSA was started in November of 2001 by the Science Data Systems Group of the NOAO Data Products Program. Version 1.0 of the NSA was released in early April, version 1.1 in July and version 1.2 in October of 2002. We discuss plans for Version 2.0 of NSA to be released in January of 2003.

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