3 Facilities Available
This section outlines the facilities available in GAIA. The hypertext version of the cookbook contains
links to ‘outline recipes’ which summarise how to use these facilities. These outline recipes
complement the smaller number of detailed recipes in Part II of the cookbook. The facilities provided
by GAIA divide naturally into three areas:
- image display,
- image analysis,
- remote access to catalogues and image databases via the Internet.
The facilities available in each of these three areas are briefly outlined below.
3.1 Image Display
- Opening files, displaying more than one image, maximising the display
Controlling the view
- Changing the zoom, position, detail and colours.
Inspecting image values
- Panel readouts, interactive slices, pixel table.
- Creating, resizing, moving, deleting, saving and restoring.
- Image and overlay graphics, colour ramp.
3.2 Image Analysis
- applying and displaying celestial coordinates to an image.
- interactive measurements of selected stars using a circular or elliptical aperture.
Automatic object detection
- automatic detection of the objects in an image. A set of parameters
(positions, brightness, ellipticity etc) are computed for all the objects detected.
- Surface photometry of galaxies, including determining radial profiles
and fitting elliptical isophotes.
- interactive removal of image blemishes and contaminating objects from an
image. For example, foreground stars might be removed from a galaxy image.
Properties of image regions
- statistics, extraction and removal of shaped regions of an image.
- two images can be compared by either plotting one as a set of contours
superimposed on the other or by blinking between the two images (cf the ‘blink
comparator’ used to compare two photographic plates).
Object position and statistics
- two-dimensional Gaussian fits to single or multiple objects.
- polarisation maps can be plotted, regions selected from them etc. These
facilities are intended to be used in conjunction with the POLPACK package for
polarimetry and spectropolarimetry (see SUN/223).
Profiles of rectangular regions
- Interactive averaged profiles along the
axes of a rectangle.
3.3 Catalogues and Online Resources
Catalogues and image stores
- Access to remote on-line catalogues, image stores and archives
via the Internet. Local catalogues can also be read and written.
Copyright © 2001 Council for the Central Laboratory of the Research Councils