AstroGrid-D: Grid technology for astronomical science

We present status and results of AstroGrid-D, a joint effort of astrophysicists and computer scientists to employ grid technology for scientific applications. AstroGrid-D provides access to a network of distributed machines with a set of commands as well as software interfaces. It allows simple use of computer and storage facilities and to schedule or monitor compute tasks and data management. It is based on the Globus Toolkit middleware (GT4).Chapter 1 describes the context which led to the demand for advanced software solutions in Astrophysics, and we state the goals of the project.We then present characteristic astrophysical applications that have been implemented on AstroGrid-D in chapter 2. We describe simulations of different complexity, compute-intensive calculations running on multiple sites (Section 2.1), and advanced applications for specific scientific purposes (Section 2.2), such as a connection to robotic telescopes (Section 2.2.3). We can show from these examples how grid execution improves e.g. the scientific workflow.Chapter 3 explains the software tools and services that we adapted or newly developed. Section 3.1 is focused on the administrative aspects of the infrastructure, to manage users and monitor activity. Section 3.2 characterises the central components of our architecture: The AstroGrid-D information service to collect and store metadata, a file management system, the data management system, and a job manager for automatic submission of compute tasks.We summarise the successfully established infrastructure in chapter 4, concluding with our future plans to establish AstroGrid-D as a platform of modern e-Astronomy.     

Scalable desktop visualisation of very large radio astronomy data cubes

Observation data from radio telescopes is typically stored in three (or higher) dimensional data cubes, the resolution, coverage and size of which continues to grow as ever larger radio telescopes come online. The Square Kilometre Array, tabled to be the largest radio telescope in the world, will generate multi-terabyte data cubes – several orders of magnitude larger than the current norm. Despite this imminent data deluge, scalable approaches to file access in Astronomical visualisation software are rare: most current software packages cannot read astronomical data cubes that do not fit into computer system memory, or else provide access only at a serious performance cost. In addition, there is little support for interactive exploration of 3D data.We describe a scalable, hierarchical approach to 3D visualisation of very large spectral data cubes to enable rapid visualisation of large data files on standard desktop hardware. Our hierarchical approach, embodied in the AstroVis prototype, aims to provide a means of viewing large datasets that do not fit into system memory. The focus is on rapid initial response: our system initially rapidly presents a reduced, coarse-grained 3D view of the data cube selected, which is gradually refined. The user may select sub-regions of the cube to be explored in more detail, or extracted for use in applications that do not support large files. We thus shift the focus from data analysis informed by narrow slices of detailed information, to analysis informed by overview information, with details on demand. Our hierarchical solution to the rendering of large data cubes reduces the overall time to complete file reading, provides user feedback during file processing and is memory efficient. This solution does not require high performance computing hardware and can be implemented on any platform supporting the OpenGL rendering library.     

Astro-WISE interfaces

From a simple text interface to a graphical user interfaces—Astro-WISE provides the user with a wide range of possibilities to interact with the information system according to the user’s tasks and use cases. We describe a general approach to the interfacing of a scientific information system. We use this approach to create a number of services, which allows the user to browse the data stored in the system, to process the data and to exchange the newly created images and catalogs with the users within the system and wider astronomical community. Reusability of interfaces and services is another important feature of our approach. It reduces the time and resources spent to interface other information systems created from Astro-WISE.     

An overview of the astrophysics data system

The Astrophysics Data System (ADS) is a distributed data system that provides access to astronomical data and literature information. The data are stored at different data centers. They are searched and retrieved by the users in real time over the Internet The ADS provides access to about 300 catalogs and 4 data archives. In addition about 160,000 abstracts from the astronomical literature can be searched. Besides the data access the ADS provides services such as plotting and image display tools, coordinate conversion tools and table manipulation capabilities. The ADS is available for free to users interested in astronomical data worldwide. Currently there are no restrictions to accessing any of the data in the ADS.     

The NASA Astrophysics Data System: Free Access to the Astronomical Literature On-line and through Email

The Astrophysics Data System (ADS) provides access to the astronomical literature through the World Wide Web. It is a NASA funded project and access to all the ADS services is free to everybody world-wide. The ADS Abstract Service allows the searching of four databases with abstracts in Astronomy, Instrumentation, Physics/Geophysics, and the LANL Preprints with a total of over 2.2 million references. The system also provides access to reference and citation information, links to on-line data, electronic journal articles, and other on-line information. The ADS Article Service contains the full articles for most of the astronomical literature back to volume 1. It contains the scanned pages of all the major journals (Astrophysical Journal, Astronomical Journal, Astronomy & Astrophysics, Monthly Notices of the Royal Astronomical Society, and Solar Physics), as well as most smaller journals back to volume 1.The ADS can be accessed through any web browser without signup or login. Alternatively an email interface is available that allows our users to execute queries via email and to retrieve scanned articles via email. This might be interesting for users on slow or unreliable links, since the email system will retry sending information automatically until the transfer is complete. There are now 9 mirror sites of the ADS available in different parts of the world to improve access. The ADS is available at: http://ads.harvard.edu This revised version was published online in July 2006 with corrections to the Cover Date.     

PROBA2: Mission and Spacecraft Overview

Within the European Space Agency’s (ESA) General Support and Technology Programme (GSTP), the Project for On-Board Autonomy (PROBA) missions provide a platform for in-orbit technology demonstration. Besides the technology demonstration goal, the satellites allow to provide services to, e.g., scientific communities. PROBA1 has been providing multi-spectral imaging data to the Earth observation community for a decade, and PROBA2 provides imaging and irradiance data from our Sun to the solar community. This article gives an overview of the PROBA2 mission history and provides an introduction to the flight segment, the ground segment, and the payload operated onboard. Important aspects of the satellite’s design, including onboard software autonomy and the functionality of the navigation and guidance, are discussed. PROBA2 successfully proved again within the GSTP concept that it is possible to provide a fast and cost-efficient satellite design and to combine advanced technology objectives from industry with focussed objectives from the science community.     

基于GPS导航的嵌入式软件设计与实现

采用GPS定位技术 ,在WindowsCE的嵌入式环境中设计并实现了一套可广泛应用于智能交通系统 (ITS)和基于位置服务 (LBS)等系统中的具有定位导航服务功能的导航软件     

The Astro-WISE approach to quality control for astronomical data

We present a novel approach to quality control during the processing of astronomical data. Quality control in the Astro-WISE Information System is integral to all aspects of data handing and provides transparent access to quality estimators for all stages of data reduction from the raw image to the final catalog. The implementation of quality control mechanisms relies on the core features in this Astro-WISE Environment (AWE): an object-oriented framework, full data lineage, and both forward and backward chaining. Quality control information can be accessed via the command-line awe-prompt and the web-based Quality-WISE service. The quality control system is described and qualified using archive data from the 8-CCD Wide Field Imager (WFI) instrument (http://www.eso.org/lasilla/instruments/wfi/) on the 2.2-m MPG/ESO telescope at La Silla and (pre-)survey data from the 32-CCD OmegaCAM instrument (http://www.astro-wise.org/~omegacam/) on the VST telescope at Paranal.     

INES: Astronomy Data Distribution for the Future

We describe here the structure under which the IUE Project will leave its archive at the completion of the distribution system and final data processing, within the INES system.The INES system is a total system, which comprises both the data in their final bulk processing mode for direct application to scientific analysis, as well as the software driving the distributed service for data retrieval directly by the end user.As a consequence of the expected long-term usage and support needs, it has been designed to require minimum maintenance costs and will not suffer single point failures because of the distributed nature. Integration of the INES system in a more general multi-wavelength archive for specialized analysis is anticipated tobe relatively easy, so further evolution of the data availabilitywill be driven fully by the users community and will evolve as thedata needs of the community develop. The long term responsibilitywill be transferred from ESA to the astronomical community throughthe establishment of the INES Principal Centre at the LAEFF Instituteof INTA in Spain.     

Scientific Research using the Electronic Archive of the Hubble Space Telescope

The Hubble Space Telescope (HST), a collaborative project between the US National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) has been operating since 1990. The European HST Science Data Archive, operated at the Space Telescope European Coordinating Facility(ST-ECF) in Garching, Germany, contains all data taken with the scienceinstruments of the HST. The services of the Archive include data browsing,preview, retrieval and re-calibration. Access to the Archive is providedthrough the World Wide Web, data distribution is through the Internet oron bulk media.This paper describes the data products, access to theArchive services, and the procedures for the use of the HST Science DataArchive by qualified scientists from remote locations. The Archive providestools implemented as Java Applets which can be used over the Net. For moresophisticated operations access to a suitable data analysis system isrequired; such software can be downloaded from our site.     

A New Approach for Scientific Data Dissemination in Developing Countries: A Case of Indonesia

This short paper is a progress report on our experiences in Indonesia of collecting, integrating and disseminating both global and local scientific data across the country through the web. Our recent efforts are concentrated on improving local public access to global scientific data, and encouraging local scientific data to be more accessible for global communities. We have maintained a well-connected infrastructure and web-based information management systems to realize these objectives. This paper is especially focused on introducing the ARSIP system for mirroring global data and sharing local scientific data, and the newly developed Indonesian Scientific Index for integrating local scientific data through an automated intelligent indexing system.     

Tracing and using data lineage for pipeline processing in Astro-WISE

Most workflow systems that support data provenance primarily focus on tracing lineage of data. Data provenance by data lineage provides the derivation history of data including information about services and input data that contributed to the creation of a data product. We show that tracing lineage by means of full backward chaining not only enables users to share, discover and reuse the data, but also supports scientific data processing through storage, retrieval and (re)processing of digitized scientific data. In this paper, we present Astro-WISE, a distributed system for processing, analyzing and disseminating wide field imaging astronomical data. We show how Astro-WISE traces lineage of data and how it facilitates data processing, retrieval, storage and archiving. Particularly we show how it solves issues related to the changing data items typical for the scientific environment, such as physical changes in calibrations, our insight in these changes and improved methods for deriving results.     

The SORCE Science Data System

The SORCE Science Data System produces total solar irradiance (TSI) and spectral solar irradiance (SSI) data products on a daily basis, which are formulated using measurements from the four primary instruments onboard the SORCE spacecraft. The Science Data System utilizes raw spacecraft and instrument telemetry, calibration data, and other ancillary information to produce and distribute a variety of data products that have been corrected for all known instrumental and operational effects. SORCE benefits from a highly optimized object-oriented data processing system in which all data are stored in a commercial relational database system, and the software itself determines the versions of data products at run-time. This unique capability facilitates optimized data storage and CPU utilization during reprocessing activities by requiring only new data versions to be generated and stored. This paper provides an overview of the SORCE data processing system, details its design, implementation, and operation, and provides details on how to access SORCE science data products.     

Bayesian approach for counting experiment statistics applied to a neutrino point source analysis

In this paper we present a model independent analysis method following Bayesian statistics to analyse data from a generic counting experiment and apply it to the search for neutrinos from point sources. We discuss a test statistic defined following a Bayesian framework that will be used in the search for a signal. In case no signal is found, we derive an upper limit without the introduction of approximations. The Bayesian approach allows us to obtain the full probability density function for both the background and the signal rate. As such, we have direct access to any signal upper limit. The upper limit derivation directly compares with a frequentist approach and is robust in the case of low-counting observations. Furthermore, it allows also to account for previous upper limits obtained by other analyses via the concept of prior information without the need of the ad hoc application of trial factors. To investigate the validity of the presented Bayesian approach, we have applied this method to the public IceCube 40-string configuration data for 10 nearby blazars and we have obtained a flux upper limit, which is in agreement with the upper limits determined via a frequentist approach. Furthermore, the upper limit obtained compares well with the previously published result of IceCube, using the same data set.     

Software design for panoramic astronomical pipeline processing

We describe the software requirement and design specifications for all-sky panoramic astronomical pipelines. The described software aims to meet the specific needs of superwide-angle optics, and includes cosmic-ray hit rejection, image compression, star recognition, sky opacity analysis, transient detection and a web server allowing access to real-time and archived data. The presented software is being regularly used for the pipeline processing of 11 all-sky cameras located in some of the world's premier observatories. We encourage all-sky camera operators to use our software and/or our hosting services and become part of the global Night Sky Live network.     

A protocol standard for heterogeneous telescope networks

The scientific need for a standard protocol permitting the exchange of generic observing services is rapidly escalating as more observatories adopt service observing as a standard operating mode and as more remote or robotic telescopes are brought on‐line. To respond to this need, we present the results of the first interoperability workshop for Heterogeneous Telescope Networks (HTN) held in Exeter. We present a draft protocol, designed to be independent of the specific instrumentation and software that controls the remote and/or robotic telescopes, allowing these telescopes to appear to the user with a unified interface despite any underlying architectural differences. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Initial data release from the INT Photometric Hα Survey of the Northern Galactic Plane (IPHAS)

The INT/WFC Photometric Hα Survey of the Northern Galactic Plane (IPHAS) is an imaging survey being carried out in  Hα, r '  and   i '  filters, with the Wide Field Camera (WFC) on the 2.5-m Isaac Newton Telescope (INT) to a depth of   r '= 20  (10σ). The survey is aimed at revealing the large scale organization of the Milky Way and can be applied to identifying a range of stellar populations within it. Mapping emission line objects enables a particular focus on objects in the young and old stages of stellar evolution ranging from early T-Tauri stars to late planetary nebulae. In this paper we present the IPHAS Initial Data Release, primarily a photometric catalogue of about 200 million unique objects, coupled with associated image data covering about 1600 deg² in three passbands. We note how access to the primary data products has been implemented through use of standard virtual observatory publishing interfaces. Simple traditional web access is provided to the main IPHAS photometric catalogue, in addition to a number of common catalogues (such as 2MASS) which are of immediate relevance. Access through the AstroGrid VO Desktop opens up the full range of analysis options, and allows full integration with the wider range of data and services available through the Virtual Observatory. The IDR represents the largest data set published primarily through VO interfaces to date, and so stands as an exemplar of the future of survey data mining. Examples of data access are given, including a cross-matching of IPHAS photometry with sources in the UKIDSS Galactic Plane Survey that validates the existing calibration of the best data.     

Near Real-Time Image Reconstruction

In recent years, post-facto image-processing algorithms have been developed to achieve diffraction-limited observations of the solar surface. We present a combination of frame selection, speckle-masking imaging, and parallel computing which provides real-time, diffraction-limited, 256×256 pixel images at a 1-minute cadence. Our approach to achieve diffraction limited observations is complementary to adaptive optics (AO). At the moment, AO is limited by the fact that it corrects wavefront abberations only for a field of view comparable to the isoplanatic patch. This limitation does not apply to speckle-masking imaging. However, speckle-masking imaging relies on short-exposure images which limits its spectroscopic applications. The parallel processing of the data is performed on a Beowulf-class computer which utilizes off-the-shelf, mass-market technologies to provide high computational performance for scientific calculations and applications at low cost. Beowulf computers have a great potential, not only for image reconstruction, but for any kind of complex data reduction. Immediate access to high-level data products and direct visualization of dynamic processes on the Sun are two of the advantages to be gained.