基于JDBC的通用数据库访问和星表录人工具

LAMOST（Large Sky Area Multi-Object Fiber Spectroscopy Telescope）的巡天战略系统的主要功能是安排观测计划,而规划巡天星表是开展所有工作的初始步骤。天文研究人员或者巡天观测人员需要从各种类型的数据库进行选星、提取和录入。使用JDBC（Java Database Connectivity）数据库访问技术,利用面向对象的编程思想,实现了一个能访问多种类型数据库、获取星表数据、数据格式转换和星表录入的工具,支持大数据量处理,为天文研究人员以及巡天观测管理人员提供帮助。     

基于JDBC的通用数据库访问和星表录入工具

LAMOST(Large Sky Area Multi-Object Fiber Spectroscopy Telescope)的巡天战略系统的主要功能是安排观测计划,而规划巡天星表是开展所有工作的初始步骤。天文研究人员或者巡天观测人员需要从各种类型的数据库进行选星、提取和录入。使用JDBC(JavaDatabase Connectivity)数据库访问技术,利用面向对象的编程思想,实现了一个能访问多种类型数据库、获取星表数据、数据格式转换和星表录入的工具,支持大数据量处理,为天文研究人员以及巡天观测管理人员提供帮助。     

面向海量天文数据的分布式MySQL锥形检索研究

随着巡天观测计划的进行,传统的数据库技术无法满足海量天文数据的存储以及检索性能的需求。针对海量天文数据存储以及锥形检索的高并发、高性能问题,采用数据库中间件技术,当海量数据到达传统数据库存储阈值时,能够通过中间件技术以分库分表的形式存储到数据库集群,充分整合关系型数据库和分布式技术的优点。利用MySQL数据库集成动态索引工具(Dynamic Index Facility, DIF)插件,在分布式数据库中建立伪球面索引,能够满足海量天文数据锥形索引的需求。     

《天文学名词》数据库新版网站设计与实现

<天文学名词>数据库网站是天文学名词审定委员会开展名词审定工作和为广大用户提供名词查询检索以及其它相关服务的网络平台.随着名词审定工作的不断推进和广大用户对名词数据库功能需求的不断增加,原有的网络平台从功能和信息量上都无法满足当前的需求.<天文学名词>数据库新版网站借助成熟的数据库和网络技术,围绕名词的征集、审定、发布、查询检索等环节,充分实现了广大用户和天文学名词审定委员会所需要的功能.提供了更加丰富的信息.介绍了新版数据库及网站的设计原则、实现方法,并从功能需求出发着重介绍后台数据库和用户界面的设计与实现.<天文学名词>数据库网站是一个典型的由数据库驱动的简单网络应用系统,本文所涉及的工作和介绍的经验将为类似应用系统的开发提供切实可行的参考.     

一种基于微信小程序在RTS2的控制框架扩展

望远镜自主控制是现代天文观测技术的重要组成部分,在当前主流的自主控制系统中,开源的远程望远镜控制系统第2版具备模块化和即插即用的设计理念,且具有快速响应能力和稳定工作的特点,被广泛应用于天文望远镜自主控制系统。由于远程望远镜控制系统第2版基于Linux平台,主要基于命令行界面(Command-Line Interface,CLI)进行远程访问控制,所以对观测人员的要求比较高。深入分析远程望远镜控制系统第2版,对JS对象标记应用程序编程接口(Java Script Object Notation Application Programming Interface,JSONAPI)进行适度改造,以JS对象标记(Java Script Object Notation,JSON)为数据传输格式,以移动终端的微信应用作为载体,跨越不同平台对天文望远镜控制系统进行数据访问和功能调用。利用微信小程序,将控制系统移植到微信小程序中,使天文技术研究人员能够方便快捷地利用移动终端在微信平台上远程控制天文望远镜和实时监控天文望远镜自主控制系统的状态。采用该模式,可扩展到天文公共对象模型(Astronomy Common Object Model,ASCOM)等其他自主控制架构,从而实现一个通用的基于微信小程序的移动终端远程控制系统。     

天文文献全文检索系统的研究与实现

介绍在对全文数据库和全文检索有关技术研究分析的基础上,以天文文献作为处理对象,开发Internet网络环境下基于Lucene检索引擎的天文文献全文检索系统,实现了无需后台数据库的天文文献全文检索系统。全文检索系统在网络环境下运行。     

天文数据库回顾与展望

随着新一代巡天观测、时域观测等天文项目的推进,当前的天文数据量越来越大。面对天文领域日益增长的大数据集和大数据流,需要一些高效的数据存储和数据处理方法来对数据进行管理。天文数据库以及在其基础上提供的数据服务的出现部分解决了这样的问题。借助于计算机技术和信息技术的进步,一些更加专业的针对天文领域的数据发现、数据挖掘、数据交互等工作正在逐步标准化。基于虚拟天文台技术和天文信息学的新型天文数据服务正深入天文用户的日常科研生活中。首先简单回顾了天文数据库的历史,然后通过对几个典型天文数据库的举例分析,从天文数据库的类型、提供的服务等方面介绍了当前天文数据库的特点和最新进展,并对今后天文数据库的发展做了展望。     

ASO-S卫星工程科学应用系统的数据库设计

先进天基太阳天文台(Advanced Space-based Solar Observatory, ASO-S)卫星是我国首颗太阳观测卫星, 主要观测太阳耀斑和日冕物质抛射以及产生它们的磁场结构. ASO-S卫星的科学应用系统是科学卫星工程的6大系统之一, 它连接科学用户和卫星数据, 为将卫星的科学数据转化为科学成果提供保障. 科学应用系统的数据库是连接软件与海量数据的枢纽, 为科学数据生产和用户服务及运行提供数据层的支撑. 介绍了科学应用系统的数据库架构设计、数据库的选择以及数据库性能优化和表样例. 这里的数据库包括观测计划、工程参数、运维日志、科学数据、定标数据和特征事件识别等数据库. 这些数据库的建设将为ASO-S卫星工程科学应用系统的顺利运行提供数据支撑, 也可以为未来其他科学卫星类似数据库的搭建提供参考和借鉴.     

天文星表入库的自动化

天文数据主要包括星表、星图、光谱、文献资料等,其中星表是包含天体信息的数据表格,是天文学家最常用到的天文数据。目前天文数据分布存储在全球各个数据中心。中国最大的天文数据中心是北京天文数据中心,其数据库的重要部分是天文星表数据库。本文阐述了建设天文星表数据库的意义,着重探讨了星表自动入库工具的实现,并介绍了在天文星表数据库基础上的数据融合和数据挖掘。     

蓬勃发展的美国大型天文数据库

近几十年,在建设天文数据库,特别是空间天文数据库方面美国科学家们做了大量的工作,积累了丰富的数据资料。这是美国,也是全世界天文学家的共同宝藏。本文概略介绍了这些美国大型天文数据库的收藏内容、存取方式、以及所提供的服务,旨在使我国天文工作者更加重视这些珍贵的资料,进而去充分开发和利用它们。     

Using Java for distributed computing in the Gaia satellite data processing

In recent years Java has matured to a stable easy-to-use language with the flexibility of an interpreter (for reflection etc.) but the performance and type checking of a compiled language. When we started using Java for astronomical applications around 1999 they were the first of their kind in astronomy. Now a great deal of astronomy software is written in Java as are many business applications. We discuss the current environment and trends concerning the language and present an actual example of scientific use of Java for high-performance distributed computing: ESA’s mission Gaia. The Gaia scanning satellite will perform a galactic census of about 1,000 million objects in our galaxy. The Gaia community has chosen to write its processing software in Java. We explore the manifold reasons for choosing Java for this large science collaboration. Gaia processing is numerically complex but highly distributable, some parts being embarrassingly parallel. We describe the Gaia processing architecture and its realisation in Java. We delve into the astrometric solution which is the most advanced and most complex part of the processing. The Gaia simulator is also written in Java and is the most mature code in the system. This has been successfully running since about 2005 on the supercomputer “Marenostrum” in Barcelona. We relate experiences of using Java on a large shared machine. Finally we discuss Java, including some of its problems, for scientific computing.     

A parameter database for large scientific projects: application to the Gaia space astrometry mission

The parallel development of many aspects of a complex space science mission like Gaia, which includes numerous participants in ESA, industrial companies, and a large and active scientific collaboration throughout Europe, makes keeping track of the many design changes, instrument and operational parameters, and numerical values for the data analysis and simulations, a challenging but crucially important problem. A comprehensive, easily-accessible, up-to-date, and definitive compilation of a large range of numerical quantities is required, and the Gaia parameter database has been established to satisfy these needs. The database is a centralised repository containing, besides mathematical, physical, and astronomical constants, many satellite and subsystem design parameters. Version control provides both a ‘live’ version with the most recent parameters, as well as previous ‘reference’ versions of the full database contents. Query results are formatted by default in HTML, while an important feature is that data can also be retrieved as Java, ANSI-C, C++, Ruby, or XML structures for direct inclusion into software codes, such that all collaborating scientists can use the retrieved database parameters and values directly linked to computational routines.     

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.     

Estimation of Light Time Effects for Close Binaries in Triple Systems

We discuss implementation of light time effects in a general binary star program that solves for third body orbit parameters and binary star parameters together. The program combines radial velocities and light curves within a coherent analysis and can use data that are very unevenly distributed over time. By analyzing whole curves, the program has access to more information than only from eclipse timings. Results for λ Tau and VV Ori are shown.     

The Kepler Mission: Astrophysics and Eclipsing Binaries

The Kepler Mission is a photometric space mission that will continuously observe a single 100 square degree field of view (FOV) of the sky of more than 100,000 stars in the Cygnus-Lyra region for four or more years with a precision of 14 parts per million (ppm) for a 6.5 hour integration including shot noise for a twelfth magnitude star. The primary goal of the mission is to detect Earth-size planets in the habitable zone of solar-like stars. In the process, many eclipsing binaries (EB) will also be detected. Prior to launch, the stellar characteristics will have been determined for all the stars in the FOV with K<14.5. As part of the verification process, stars with transits (about 5%) will need to have follow-up radial velocity observations performed to determine the component masses and thereby separate grazing eclipses caused by stellar companions from transits caused by planets. The result will be a rich database on EBs. The community will have access to the archive for uses such as for EB modeling of the high-precision light curves. A guest observer program is also planned for objects not already on the target list.     

Recursive calculation of hansen coefficients

Hansen coefficients are used in expansions of the elliptic motion. Three methods for calculating the coefficients are studied: Tisserand's method, the Von Zeipel-Andoyer (VZA) method with explicit representation of the polynomials required to compute the Hansen coefficients, and the VZA method with the values of the polynomials calculated recursively. The VZA method with explicit polynomials is by far the most rapid, but the tabulation of the polynomials only extends to 12th order in powers of the eccentricity, and unless one has access to the polynomials in machine-readable form their entry is laborious and error-prone. The recursive calculation of the VZA polynomials, needed to compute the Hansen coefficients, while slower, is faster than the calculation of the Hansen coefficients by Tisserand's method, up to 10th order in the eccentricity and is still relatively efficient for higher orders. The main advantages of the recursive calculation are the simplicity of the program and one's being able to extend the expansions to any order of the eccentricity with ease. Because FORTRAN does not implement recursive procedures, this paper used C for all of the calculations. The most important conclusion is recursion's genuine usefulness in scientific computing.     

The MultiDark Database: Release of the Bolshoi and MultiDark cosmological simulations

We present the online MultiDark Database – a Virtual Observatory‐oriented, relational database for hosting various cos‐mological simulations. The data is accessible via an SQL (Structured Query Language) query interface, which also allows users to directly pose scientific questions, as shown in a number of examples in this paper. Further examples for the usage of the database are given in its extensive online documentation. The database is based on the same technology as the Millennium Database, a fact that will greatly facilitate the usage of both suites of cosmological simulations. The first release of the MultiDark Database hosts two 8.6 billion particle cosmological N‐body simulations: the Bolshoi (250 h^–1 Mpc simulation box, 1 h^–1 kpc resolution) and MultiDark Run1 simulation (MDR1, or BigBolshoi, 1000 h^–1 Mpc simulation box, 7 h^–1 kpc resolution). The extraction methods for halos/subhalos from the raw simulation data, and how this data is structured in the database are explained in this paper. With the first data release, users get full access to halo/subhalo catalogs, various profiles of the halos at redshifts z = 0–15, and raw dark matter data for one time‐step of the Bolshoi and four time‐steps of the MultiDark simulation. Later releases will also include galaxy mock catalogs and additional merger trees for both simulations as well as new large volume simulations with high resolution. This project is further proof of the viability to store and present complex data using relational database technology. We encourage other simulators to publish their results in a similar manner. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)