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VOMegaPlot, a Java based tool, has been developed for visualizing astronomical data that is available in VOTable format. It has been specifically optimized for handling large number of points (in the range of millions). It has the same look and feel as  VOPlot and both these tools have certain common functionality.

VOMegaPlot stores the data present in a VOTable xml file into data structures, which are serialized on the disk in a plot-friendly format. During the actual plotting operation, only the relevant data necessary for plotting is loaded. This significantly reduces the memory requirements and allows plotting of large VOTables. When VOMegaPlot is to be used with a very large catalogue, the catalogue has to be pre-processed to produce a series of data files using a straightforward procedure which is provided. This is to be done just once for a given VOTable, and the plotter uses the whole set of files when it is invoked subsequently.

VOMegaPlot uses Ptplot 5.2, a 2D data plotter and histogram tool implemented in Java. Ptplot has been developed at Electrical Engineering & Computer Science department at the University of California, Berkeley and is freely available under a BSD style license.

VOMegaPlot has been developed as a part of the Virtual Observatory - India initiative by Persistent Systems Ltd. (PSL) and the Inter-University Centre for Astronomy and Astrophysics (IUCAA), in collaboration with Centre de Données astronomiques de Strasbourg (CDS), Strasbourg and with support from the European AVO project. The collaboration between VO-I and CDS extends to several related projects. The VO-I project is supported by the Ministry of Communication and Information Technology of the Government of India.



Download File


Released On




22 June 2007




09 May 2006

Click here to download parsed files for tycho-1 catalogue.

Click here to download parsed files for tycho-2 catalogue.

Change log for VOMegaPlot is available here.

Please send comments and questions to voindia@iucaa.in

Please click here for the disclaimer

Future Development

Future version of VOMegaPlot would include features like selection of points, creation of new columns and filters that are currently available with VOPlot.



This project is supported by the Ministry of Communication and Information Technology

   Virtual Observatory India