GAIA - Graphical Astronomy and Image Analysis Tool

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GAIA - Graphical Astronomy and Image Analysis Tool

What is GAIA?

GAIA is an highly interactive image display tool but with the additional capability of being extendable to integrate other programs and to manipulate and display data-cubes. At present image analysis extensions are provided that cover the astronomically interesting areas of aperture & optimal photometry, automatic source detection, surface photometry, contouring, arbitrary region analysis, celestial coordinate readout, calibration and modification, grid overlays, blink comparison, image defect patching, polarization vector plotting and the ability to connect to resources available in Virtual Observatory catalogues and image archives, as well as the older Skycat formats.

GAIA also features tools for interactively displaying image planes from data-cubes and plotting spectra extracted from the third dimension. It can also display 3D visualisations of data-cubes using iso-surfaces and volume rendering.

Specialised handling of data from the CUPID package provides the visualisation of clumps of emission in 2D and 3D, as ellipses, polygons and boxes. This supports the inspection of JCMT science archive advanced data products.

Interoperability with other SAMP enabled applications is provided so that GAIA can be used as part of a integrated desktop (usually querying the Virtual Observatory).


GAIA is a derivative of the Skycat catalogue and image display tool, developed as part of the VLT project at ESO. Skycat and GAIA are free software under the terms of the GNU copyright.

The 3D facilities in GAIA use the VTK library.

What can it do?

The capabilities of GAIA fall roughly into four areas; those of an image display tool, those provided for the analysis of images, those for querying on-line resources (catalogues of images and data) and cube handling. Each of these areas is described very briefly in the next lists:

  • Image Display Capabilities
    • Display of images in FITS and Starlink NDF formats.
    • Panning, zooming, data range and colour table changes.
    • Continuous display of the cursor position and image data value.
    • Display of many images.
    • Annotation, using text and line graphics (boxes, circles, polygons, lines with arrowheads, ellipses...).
    • Printing.
    • Real time pixel value table.
    • Display of image planes from data cubes.
    • Display of point and region spectra extracted from cubes.
    • Display of images and catalogues from SAMP-aware applications.
    • Selection of 2D or 3D regions using an integer mask.
  • Image Analysis Capabilities
    • Aperture photometry.
    • Optimal photometry.
    • Automated object detection.
    • Extended surface photometry.
    • Image patching.
    • Arbitrary shaped region analysis.
    • Contouring.
    • Polarization vector plotting and manipulation.
    • Blink comparison of displayed images.
    • Interactive position marking.
    • Celestial co-ordinates readout.
    • Astrometric calibration.
    • Astrometric grid overlay.
    • Celestial co-ordinate system selection.
    • Sky co-ordinate offsets.
    • Real time profiling.
    • Object parameterization.
  • Catalogue Capabilities
    • VO capabilities
      • Cone search queries
      • Simple image access queries
    • Skycat capabilities
      • Plot positions in your field from a range of on-line catalogues (various, including HST guide stars).
      • Query databases about objects in field (NED and SIMBAD).
      • Display images of any region of sky (Digital Sky Survey).
      • Query archives of any observations available for a region of sky (HST, NTT and CFHT).
      • Display positions from local catalogues (allows selection and fine control over appearance of positions).
  • 3D Cube Handling
    • Display of image slices from NDF and FITS cubes.
    • Continuous extraction and display of spectra.
    • Collapsing, animation, detrending, filtering.
    • 3D visualisation with iso-surfaces and volume rendering.
    • Celestial, spectral and time coordinate handling.
  • CUPID catalogues and masks
    • Display catalogues in 2 or 3D
    • Display selected regions of masks in 2 or 3D

Getting started

The latest version of GAIA is available in the EAO Starlink release.

Once installed you should be able to view the documentation (SUN/214) that came with GAIA using the command:

    % showme sun214

To start using GAIA look at the "Getting Started" section. On-line help is available in the "Help" menu.

If you'd like further help, or would like to get some ideas for using GAIA more effectively, then try the GAIA Cookbook (SC/17).

Current status

GAIA is currently at version 4.4-4, which is part of the {CURRENT} release. The changes in this release are described in the current news file.


The following information about GAIA is available on-line:

A lot of pretty pictures and walkthoughs are also available in the GAIA Index side box.

Re-current problems and bugs

Unresponsive toolboxes on laptops

There seems to be a recurrent issue setting up laptops to run GAIA The symptoms of this are that GAIA may refuse to start up, may hang when using some of the toolboxes, or may refuse to respond to remote requests. The problem is that the local networking isn't working correctly due to a misconfiguration of the /etc/hosts file. This should contain a line like:       localhost       localhost.localdomain

or possibly:    _what_hostname_says_   localhost    localhost.localdomain

When the machine is part of a domain, i.e. the "hostname" command returns "name.domain" rather than just "name" or "localhost".

Questions or comments to:

Copyright © 2005 Central Laboratory of the Research Councils
Copyright © 2006 Particle Physics and Astronomy Research Council
Copyright © 2008-2009 Science and Technlogy Facilities Council
Copyright © 2009-2013 Peter W. Draper
Last modified: 02-Jun-2016
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