GAIA -- Graphical Astronomy and Image Analysis Tool

Welcome to the on-line help system. For help on any of the topics shown below, click on the associated hyperlink. Descriptions and pointers to other sources are available in the main GAIA documentation, Starlink User Note 214 (SUN/214). This can be view on-line either by using the command:

   % showme sun214

If you need help beyond what is available in these resources (or have any suggestions for improvements), then join the Starlink user support mailing lists at:

The GAIA home page is at:

which may be updated from time-to-time.

GAIA was created by the now closed Starlink UK project, funded by the UK Particle Physics and Astronomy Research Council ( and has been more recently supported by the Joint Astronomy Centre Hawaii (, by funding from PPARC and more recently the UK Science and Technology Facilities Council (

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

Help topics

The help is roughly divided into three areas, those of an image display tool, those provided for the analysis of images and those for querying on-line resources (catalogues of images and data).

If you open a toolbox (i.e. a pop-up window) that has some specific help associated with it you'll see a "Help" menu in the top-right corner.

Image and Cube Display

  • Displaying images
    Opening files, displaying more than one image, maximising the display area
  • Displaying data-cubes
    Displaying spectra and images from cubes, volume visualisation of cubes
  • Controlling the view
    Changing the zoom, position, detail and colours
  • Inspecting image values
    Panel readouts, interactive slices, pixel table
  • Overlay graphics
    Creating, resizing, moving, deleting, saving/restoring
  • Printing or taking a snapshot
    Creating graphics and postscript representations of the image and overlay graphics or colour ramp
  • Image Analysis

  • Astrometry
    Reading coordinates, getting offsets, plotting axes, changing celestial coordinates, calibrating images, types of astrometry
  • Photometry
    Aperture (circular or elliptical), optimal, magnitudes or counts
  • Automatic object detection
    Detection and parameterization of all objects (SExtractor based)
  • Surface photometry
    Surface photometry of extended objects
  • Image patching
    Realistic removal of contaminating defects of any shape
  • Regions properties
    Statistics, extraction and removal of shaped regions
  • Image comparison
    Contouring of self and other images, blink comparison
  • Object position and statistics
    Single object 2D gaussian fits, multiple fits, position recording
  • Polarization plotting
    Display, select, edit, statistics of polarization maps
  • Profiles of rectangular regions
    Interactive averaged profiles along X and Y axes of rectangle
  • Masking images
    Using integer masks to inspect regions of an image.
  • Catalogues and Online Resources

  • Catalogues and image stores
    On-line catalogues, image stores and archives. Local catalogues. The Virtual Observatory.
  • CUPID catalogues and masks

    Visualizing clumps of emission detected by CUPID.
  • SAMP interoperability

  • SAMP interoperability
    Interoperability with other SAMP enabled applications.
  • Making hardcopies of the help pages

    Display this page in netscape (or similar web-browser with printing capabilities) use:

      % showme gaia

    Now navigate to the desired page.

    The whole on-line help system can be viewed this way, if you prefer. However, you'll lose the search facilities and connection with the toolbox "Help" menus.

    Error: table contains no columns

    If you see an error dialog with this message then the file:


    is corrupt. Close GAIA, delete this file and then restart.


    GAIA is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

    GAIA is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along with GAIA; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA, or contact GAIA support at "".