### Virtual

#### Observatory

#### Current Activities

This page describes the tools being built as part of the VOI (Virtual Observatory India) project. The project has been undertaken by the Inter-University Centre for Astronomy and Astrophysics and Persistent Systems, Pune. The following tools are currently available:

· C++ parser for VOTable

· VOPlot for plotting data from VOTables

Please send comments and questions to <voindia@vo.iucaa.ernet.in>.

Please click here for the disclaimer.

## C++ parser for VOTable

This is a C++ parser for the VOTable XML format as part of the VOI (Virtual Observatory India) project.

Downloads

# VOTable Parser Version | # Windows32 (Built with MSVC 6.0) | # Linux Redhat 7.1 (Built with g++ 2.96)
1.2 | VOTableParser1_2win32.zip | VOTableParser1_2linux.zip
1.1 | VOTableParser1_1win32.zip | VOTableParser1_2linux.zip

Change log is available here.

API Documentation is available here.

Source code is available here. Please see the copyright and disclaimer here before downloading the source code.

Salient Implementation Features

- The parser is implemented as a wrapper over XALAN-C++, an XSLT processor and provides for an API based interface to access VOTable files.
- Since XALAN-C++ is a robust implementation of is a robust implementation of the W3C Recommendations for XSL Transformations (XSLT) and the XML Path Language (XPath), XPath queries can be used to access the VOTable data. As a result future enhancements to the parser can be incorporated quickly and efficiently.

Object Model

Current Scope

- Support only for reading of tables
- Support only for pure-XML TABLEDATA and not for BINARY or FITS data streams

Coming Up Soon

· Support for streaming in order to read large VOTable documents and real time data in VOTable format.

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## VOPlot for plotting VOTables

VOPlot is a standalone java application for plotting different astronomical graphs data stored in VOTable XML format. It allows users to plot numeric data from a VOTable. A list of the features supported in the current version of the VOPlot is given below.

A web-based version of the VOPlot will soon be integrated with the VizieR Catalogue Service so that catalogues can be plotted online.

Download VOPlot v1.0

Sample Plots are available here.

User Guide is available here.

Salient Features

- Ability to plot data read from either a local or remote VOTable.
- Ability to plot different types of plots: The tool supports plotting data in the form of:

- Scatter plots – Plotting of individual points.
- Line plots – Joining the plotted points by line segments.
- Histograms

- Ability to transform data before plotting. Simple arithmetic and trigonometric functions are supported.
- Ability to filter data to create new data subsets, which can be used for plotting.
- Ability to specify manually or let the tool auto-select the axes limits.
- Ability to specify labels for the axes as well as a title for the plot.
- Ability to use logarithmic scales on axes.
- Ability to overlay different plots for the purpose of comparison.
- Ability to specify axes limits & labels after the plot is rendered.
- Ability to zoom-in & out of the plot.
- Ability to save the image of the plot as an EPS file.

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