Apex I and Apex II software packages for the reduction of astronomical CCD observations

We describe in detail the Apex I and Apex II software packages created for astrometric and photometric reductions of astronomical observations with CCD cameras. The Apex I software package has been created for the semiautomatic reduction of astronomical observations and has a convenient user interface. The Apex II software package allows for the completely automatic reduction of astrometric and photometric observations to be performed.     

RHESSI Data Analysis Software: Rationale and Methods

The Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) performs imaging spectroscopy of the Sun with high spatial and spectral resolution from 3 keV to 17 MeV using indirect Fourier-transform techniques. We review the rationale behind the RHESSI data analysis software, and explain the underlying structure of the software tools. Our goal was to make the large data set available within weeks after the RHESSI launch, and to make it possible for any member of the scientific community to analyze it easily. This paper describes the requirements for the software and explores our decisions to use the SolarSoftWare and Interactive Data Language programming packages, to support both Windows and Unix platforms, and to use object-oriented programming. We also describe how the data are rapidly disseminated and how ancillary data sets are used to enhance the RHESSI science. Finally, we give a schematic overview of some of the data flow through the high-level analysis tools. More information on the data and analysis procedures can be found at the RHESSI Data Center website, http://hesperia.gsfc.nasa.gov/rhessidatacenter. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1022444531435     

IDL in astronomy: ISOO and the ISAP project

The data processing software used for the Infrared Space Observatory ISO is briefly discussed as an example for the application of the commercial software package IDL in Astronomy. Some of the principles and details, in particular of the Quick Look Analysis, the Interactive Analysis System and the ISO Spectral Analysis Package ISAP, are described to highlight step by step many of IDL's advantages. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mass decomposition of galaxies using DECA software package

The new DECA software package, which is designed to perform photometric analysis of the images of disk and elliptical galaxies having a regular structure, is presented. DECA is written in Python interpreted language and combines the capabilities of several widely used packages for astronomical data processing such as IRAF, SExtractor, and the GALFIT code used to perform two-dimensional decomposition of galaxy images into several photometric components (bulge+disk). DECA has the advantage that it can be applied to large samples of galaxies with different orientations with respect to the line of sight (including edge-on galaxies) and requires minimum human intervention. Examples of using the package to study a sample of simulated galaxy images and a sample of real objects are shown to demonstrate that DECA can be a reliable tool for the study of the structure of galaxies.     

A systematic review of strong gravitational lens modeling software

Despite expanding research activity in gravitational lens modeling, there is no particular software which is considered a standard. Much of the gravitational lens modeling software is written by individual investigators for their own use. Some gravitational lens modeling software is freely available for download but is widely variable with regard to ease of use and quality of documentation. This review of 13 software packages was undertaken to provide a single source of information. Gravitational lens models are classified as parametric models or non-parametric models, and can be further divided into research and educational software. Software used in research includes the GRAVLENS package (with both gravlens and lensmodel), Lenstool, LensPerfect, glafic, PixeLens, SimpLens, Lensview, and GRALE. In this review, GravLensHD, G-Lens, Gravitational Lensing, lens and MOWGLI are categorized as educational programs that are useful for demonstrating various aspects of lensing. Each of the 13 software packages is reviewed with regard to software features (installation, documentation, files provided, etc.) and lensing features (type of model, input data, output data, etc.) as well as a brief review of studies where they have been used. Recent studies have demonstrated the utility of strong gravitational lensing data for mass mapping, and suggest increased use of these techniques in the future. Coupled with the advent of greatly improved imaging, new approaches to modeling of strong gravitational lens systems are needed. This is the first systematic review of strong gravitational lens modeling software, providing investigators with a starting point for future software development to further advance gravitational lens modeling research.     

基于天文开源软件的卫星干涉测量数据处理系统

VLBI (Very Long Baseline Interferometry)技术观测卫星需要对干涉测量数据进行相关和后处理,通过相关、时延校准、条纹搜索,最终得到卫星的基线几何时延.基于天文开源软件建立起一套卫星干涉测量数据处理系统.该系统可工作在实时和事后两种状态,实现相关、中性大气、电离层、钟模型以及仪器硬件的时延校准、条纹搜索、生成基线时延和时延率序列.使用该系统处理北斗GEO (Geosynchronous Earth Orbit)卫星的干涉测量试验数据,得到了精度在1–2 ns量级的卫星基线时延序列.     

Wide-field ultraviolet imager for astronomical transient studies

Though the ultraviolet (UV) domain plays a vital role in the studies of astronomical transient events, the UV time-domain sky remains largely unexplored. We have designed a wide-field UV imager that can be flown on a range of available platforms, such as high-altitude balloons, CubeSats, and larger space missions. The major scientific goals are the variability of astronomical sources, detection of transients such as supernovae, novae, tidal disruption events, and characterizing active galactic nuclei variability. The instrument has a 80 mm aperture with a circular field of view of 10.8 degrees, an angular resolution of ～22 arcsec, and a 240 - 390 nm spectral observation window. The detector for the instrument is a Microchannel Plate (MCP)-based image intensifier with both photon counting and integration capabilities. An FPGA-based detector readout mechanism and real time data processing have been implemented. The imager is designed in such a way that its lightweight and compact nature are well fitted for the CubeSat dimensions. Here we present various design and developmental aspects of this UV wide-field transient explorer.     

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.     

Astronomical image data compression by morphological skeleton transformation

Astronomical instruments currently provide a large amount of data. Nowadays, a large part of these data are image frames obtained with receivers of increasing size. The scan of large astronomical plates using fast microdensitometers gives image frames of over 30000×30000 pixels. More and more often, images are transmitted over a network in order to control the observations, to process the data, and to examine or to fill a data bank. The time taken for archiving, the cost of communication, the available memory given by magnetic tapes, and the limited bandwidth of transmission lines are reasons which lead us to examine the data compression of astronomical images.The astronomical image has the characteristic of being a set of astronomical sources in the sky background whose values are not zero. We are, in fact, only interested in the astronomical sources. Once a suitable detection is made, we generally want a compression without any distorsion. In this paper, we present a method which can be adapted for this purpose. It is based on morphological skeleton transformations. The experimental results show that it can give us an efficient compression. Moreover, the flexibility of choosing a structure element adapted to different images and the simplicity of implementation are other advantages of this method. Because of these characteristics, different compression applications may be treated.     

Novel Algorithms for Astronomical Plate Analyses

Powerful computers and dedicated software allow effective data mining and scientific analyses in astronomical plate archives. We give and discuss examples of newly developed algorithms for astronomical plate analyses, e.g., searches for optical transients, as well as for major spectral and brightness changes.     

Integral Field Spectroscopy with Gemini: Support for IFU data in the Gemini IRAF package

We present a brief overview of facilities for Integral Field Spectroscopy at the Gemini Observatory. These include four optical and near-infrared IFUs suitable for high spatial resolution work and a suite of tasks for handling IFU data in the Gemini IRAF package. We describe the tools for data reduction that are available now or planned in the near future, helping investigators make productive use of these ground-breaking instruments. Further details on the individual IFUs, specific science applications and reduction examples are given in associated presentations by Beck et al., Carrasco et al., Trancho et al. and Winge et al.     

面向Web服务的天文数据发布技术

目前主流的天文数据发布主要使用基于Web页面和基于REST风格的Web服务两种发布技术,但存在诸多不足,特别是不利于自动化工具实现机器识别并调用。WebService技术作为一种日趋成熟的分布式计算模型,拥有跨平台与松耦合等很多优势,通过Web服务实现天文数据发布可以提高天文研究工作的灵活性和自动化程度。对Web服务在虚拟天文台中的应用情况及目前主要的天文数据发布技术进行了系统的调研,并在此基础上就如何实现符合IVOA规范且面向Web服务的天文数据发布服务进行了分析,针对一个天文数据发布实例,设计并实现了同时支持SOAP风格和REST风格的锥型检索服务,测试结果表明服务设计是成功的。     

Integrating advanced visualization technology into the planetary Geoscience workflow

Recent advances in computer visualization have allowed us to develop new tools for analyzing the data gathered during planetary missions, which is important, since these data sets have grown exponentially in recent years to tens of terabytes in size. As part of the Advanced Visualization in Solar System Exploration and Research (ADVISER) project, we utilize several advanced visualization techniques created specifically with planetary image data in mind. The Geoviewer application allows real-time active stereo display of images, which in aggregate have billions of pixels. The ADVISER desktop application platform allows fast three-dimensional visualization of planetary images overlain on digital terrain models. Both applications include tools for easy data ingest and real-time analysis in a programmatic manner. Incorporation of these tools into our everyday scientific workflow has proved important for scientific analysis, discussion, and publication, and enabled effective and exciting educational activities for students from high school through graduate school.     

适用于古天文研究的计算机软件

天文软件是进行古天文研究非常有用的辅助工具。对一些常见的商业软件与专业软件的计算结果进行了分析比较,发现它们在两三百年的短期内都是足够可靠的,但是若干商业软件并不适用于涉及几千年跨度的古天文研究。分析表明:无论从数据精确度和长期稳定性,还是从功能的强大程度来说,SkyMap都是值得推广的天文计算软件。     

Why chromatic imaging matters

During the last two decades, the first generation of beam combiners at the Very Large Telescope Interferometer has proved the importance of optical interferometry for high-angular resolution astrophysical studies in the near- and mid-infrared. With the advent of 4-beam combiners at the VLTI, the u ? v coverage per pointing increases significantly, providing an opportunity to use reconstructed images as powerful scientific tools. Therefore, interferometric imaging is already a key feature of the new generation of VLTI instruments, as well as for other interferometric facilities like CHARA and JWST. It is thus imperative to account for the current image reconstruction capabilities and their expected evolutions in the coming years. Here, we present a general overview of the current situation of optical interferometric image reconstruction with a focus on new wavelength-dependent information, highlighting its main advantages and limitations. As an Appendix we include several cookbooks describing the usage and installation of several state-of-the art image reconstruction packages. To illustrate the current capabilities of the software available to the community, we recovered chromatic images, from simulated MATISSE data, using the MCMC software SQUEEZE. With these images, we aim at showing the importance of selecting good regularization functions and their impact on the reconstruction.     

人工神经网络在天文学中的应用

人工神经网络具有自学习、自适应、鲁棒性好、动态响应快等特点,并具有较强的非线性处理问题能力,因此在天文学中得到广泛而成功的应用．综述了人工神经网络在天文学中主要应用模型的基本原理和优缺点,阐述了人工神经网络适用于天文学的某些基本特征,着重介绍了人工神经网络在天文学中的具体应用实例,并对其发展和应用前景进行了展望．由于天文数据分布的庞杂和天文数据量的急剧增加,人工神经网络将日益显示出优越性．     

PINGSoft: An IDL visualisation and manipulation tool for integral field spectroscopic data

In this article we introduce PINGSoft, a set of IDL routines designed to visualise and manipulate, in an interactive and friendly way, integral field spectroscopic (reduced) data. The package is optimised for large databases and a fast visualisation rendering. Here we describe its major characteristics and requirements, providing examples and describing its capabilities. The PINGSoft package is freely available at: http://www.ast.cam.ac.uk/research/pings     

The Planck On-the-Flight Forecaster (POFF)

The Planck On-the-Flight Forecaster (POFF) is a tool to predict when a position in the sky will be within a selected angular distance from any instrument receiver direction in the Planck satellite taking into consideration its programmed observational plan. The tool has been developed in the framework of the Planck LFI Core Team activities, but it is now used by the whole Planck collaboration.In this paper we describe the tool and its applications to plan observations of point sources with other instruments which are expected to increase the scientific importance of Planck data, once they are publicly available. Collecting simultaneous multi-frequency data, like those that can be planned with the POFF, will aid the investigation of variability in point sources and also allow the reconstruction of point source spectral energy distributions over wide frequency range, thus minimizing the effect of variability itself.POFF is a combination of IDL routines which combine the publicly available information about the Planck scanning strategy with the focal plane shape to identify if a given (list of) position(s) could be observed by the satellite at a given frequency and/or by selected receivers in a given time range. The output can be displayed with any reasonable desired time resolution and with various sorting options.The code is not a Planck product, but has been validated with the Planck LFI pipeline, by searching for sources in the first satellite datasets. It has been implemented as one of the general tools of the LFI Data Processing Center. The code format and its large number of options make the program flexible and suitable for many applications, facilitating fast results.POFF is currently successfully used to plan activities within the Planck collaboration, including observations with several ground-based facilities, and is also available to the larger scientific community.