Exploration of Parameter Spaces in a Virtual Observatory

Like every other field of intellectual endeavor, astronomy is being revolutionised by the advances in information technology. There is an ongoing exponential growth in the volume, quality, and complexity of astronomical data sets, mainly through large digital sky surveys and archives. The Virtual Observatory (VO) concept represents a scientific and technological framework needed to cope with this data flood. Systematic exploration of the observable parameter spaces, covered by large digital sky surveys spanning a range of wavelengths, will be one of the primary modes of research with a VO. This is where the truly new discoveries will be made, and new insights be gained about the already known astronomical objects and phenomena. We review some of the methodological challenges posed by the analysis of large and complex data sets expected in the VO-based research. The challenges are driven both by the size and the complexity of the data sets (billions of data vectors in parameter spaces of tens or hundreds of dimensions), by the heterogeneity of the data and measurement errors, including differences in basic survey parameters for the federated data sets (e.g., in the positional accuracy and resolution, wavelength coverage, time baseline, etc.), various selection effects, as well as the intrinsic clustering properties (functional form, topology) of the data distributions in the parameter spaces of observed attributes. Answering these challenges will require substantial collaborative efforts and partnerships between astronomers, computer scientists, and statisticians.Comment: Invited review, 10 pages, Latex file with 4 eps figures, style files included. To appear in Proc. SPIE, v. 4477 (2001

Exploration of Large Digital Sky Surveys

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 profoundly change the way observational astronomy is done. Clustering analysis techniques can be used to discover samples of rare, unusual, or even previously unknown types of astronomical objects and phenomena. Exploration of the previously poorly probed portions of the observable parameter space are especially promising. We illustrate some of the possible types of studies with examples drawn from DPOSS; much more complex and interesting applications are forthcoming. Development of the new tools needed for an efficient exploration of these vast data sets requires a synergy between astronomy and information sciences, with great potential returns for both fields.Comment: To appear in: Mining the Sky, eds. A. Banday et al., ESO Astrophysics Symposia, Berlin: Springer Verlag, in press (2001). Latex file, 18 pages, 6 encapsulated postscript figures, style files include

Ranger VII Flight Path and Its Determination from Tracking Data

Flight path and tracking study of Ranger VII LUNAR prob

yourSky: rapid desktop access to custom astronomical image mosaics

The yourSky custom astronomical image mosaicking software has a Web portal architecture that allows access via ordinary desktop computers with low bandwidth network connections to high performance and highly customizable mosaicking software deployed in a high performance computing and communications environment. The emphasis is on custom access to image mosaics constructed from terabytes of raw image data stored in remote archives. In this context, custom access refers to new technology that enables on the fly mosaicking to meet user-specified criteria for region of the sky to be mosaicked, datasets to be used, resolution, coordinate system, projection, data type and image format. The yourSky server is a fully automated end-to-end system that handles all aspects of the mosaic construction. This includes management of mosaic requests, determining which input images are required to fulfill each request, management of a data cache for both input image plates and output mosaics, retrieval of input image plates from massive remote archives, image mosaic construction on a multiprocessor system, and making the result accessible to the user on the desktop. The URL for yourSky is http://yourSky.jpl.nasa.gov

The Mariner 6 and 7 flight paths and their determination from tracking data

Determination of orbit estimates for Mariner 6 and 7 space probe flight

yourSky: rapid desktop access to custom astronomical image mosaics

The yourSky custom astronomical image mosaicking software has a Web portal architecture that allows access via ordinary desktop computers with low bandwidth network connections to high performance and highly customizable mosaicking software deployed in a high performance computing and communications environment. The emphasis is on custom access to image mosaics constructed from terabytes of raw image data stored in remote archives. In this context, custom access refers to new technology that enables on the fly mosaicking to meet user-specified criteria for region of the sky to be mosaicked, datasets to be used, resolution, coordinate system, projection, data type and image format. The yourSky server is a fully automated end-to-end system that handles all aspects of the mosaic construction. This includes management of mosaic requests, determining which input images are required to fulfill each request, management of a data cache for both input image plates and output mosaics, retrieval of input image plates from massive remote archives, image mosaic construction on a multiprocessor system, and making the result accessible to the user on the desktop. The URL for yourSky is http://yourSky.jpl.nasa.gov

Architecture for access to a compute-intensive image mosaic service in the NVO

The National Virtual Observatory (NVO) will provide on-demand access to data collections, data fusion services and compute intensive applications. The paper describes the development of a framework that will support two key aspects of these objectives: a compute engine that will deliver custom image mosaics, and a "request management system," based on an e-business applications server, for job processing, including monitoring, failover and status reporting. We will develop this request management system to support a diverse range of astronomical requests, including services scaled to operate on the emerging computational grid infrastructure. Data requests will be made through existing portals to demonstrate the system: the NASA/IPAC Extragalactic Database (NED), the On-Line Archive Science Information Services (OASIS) at the NASA/IPAC Infrared Science Archive (IRSA); the Virtual Sky service at Caltech's Center for Advanced Computing Research (CACR), and the yourSky mosaic server at the Jet Propulsion Laboratory (JPL)

A method to study the effect of bronchodilators on smoke retention in COPD patients: study protocol for a randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>Chronic obstructive pulmonary disease (COPD) is a common disease, associated with cardiovascular disease. Many patients use (long-acting) bronchodilators, whilst they continue smoking alongside. We hypothesised an interaction between bronchodilators and smoking that enhances smoke exposure, and hence cardiovascular disease. In this paper, we report our study protocol that explores the fundamental interaction, i.e. smoke retention.</p> <p>Method</p> <p>The design consists of a double-blinded, placebo-controlled, randomised crossover trial, in which 40 COPD patients smoke cigarettes during both undilated and maximal bronchodilated conditions. Our primary outcome is the retention of cigarette smoke, expressed as tar and nicotine weight. The inhaled tar weights are calculated from the correlated extracted nicotine weights in cigarette filters, whereas the exhaled weights are collected on Cambridge filters. We established the inhaled weight calculations by a pilot study, that included paired measurements from several smoking regimes. Our study protocol is approved by the local accredited medical review ethics committee.</p> <p>Discussion</p> <p>Our study is currently in progress. The pilot study revealed valid equations for inhaled tar and nicotine, with an R²of 0.82 and 0.74 (p < 0.01), respectively. We developed a method to study pulmonary smoke retentions in COPD patients under the influence of bronchodilation which may affect smoking-related disease. This trial will provide fundamental knowledge about the (cardiovascular) safety of bronchodilators in patients with COPD who persist in their habit of cigarette smoking.</p> <p>Trial registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT00981851">NCT00981851</a></p

The Pioneer Anomaly

Radio-metric Doppler tracking data received from the Pioneer 10 and 11 spacecraft from heliocentric distances of 20-70 AU has consistently indicated the presence of a small, anomalous, blue-shifted frequency drift uniformly changing with a rate of ~6 x 10^{-9} Hz/s. Ultimately, the drift was interpreted as a constant sunward deceleration of each particular spacecraft at the level of a_P = (8.74 +/- 1.33) x 10^{-10} m/s^2. This apparent violation of the Newton's gravitational inverse-square law has become known as the Pioneer anomaly; the nature of this anomaly remains unexplained. In this review, we summarize the current knowledge of the physical properties of the anomaly and the conditions that led to its detection and characterization. We review various mechanisms proposed to explain the anomaly and discuss the current state of efforts to determine its nature. A comprehensive new investigation of the anomalous behavior of the two Pioneers has begun recently. The new efforts rely on the much-extended set of radio-metric Doppler data for both spacecraft in conjunction with the newly available complete record of their telemetry files and a large archive of original project documentation. As the new study is yet to report its findings, this review provides the necessary background for the new results to appear in the near future. In particular, we provide a significant amount of information on the design, operations and behavior of the two Pioneers during their entire missions, including descriptions of various data formats and techniques used for their navigation and radio-science data analysis. As most of this information was recovered relatively recently, it was not used in the previous studies of the Pioneer anomaly, but it is critical for the new investigation.Comment: 165 pages, 40 figures, 16 tables; accepted for publication in Living Reviews in Relativit