### 2 Getting Started

The following two sections describe the absolute basics of how to startup GAIA and how to display images using it.

If you need help beyond this, and are new to GAIA, then you should probably read the ‘The GAIA CookBook’ (SC/17). In addition to the usual introductory text this also contains several recipes for achieving specific tasks (such as measuring instrumental magnitudes and making use of celestial coordinate information, although at the time of writing the astrometric calibration sections are now out of date with the arrival of the new toolboxes based on AUTOASTROM).

The other main source of information about GAIA is the on-line help system. This can be accessed after starting GAIA (just select the Help menus). Many windows also feature ‘short help’. This is a retangular region at the bottom of a window that may display a one-line description of the window element under the cursor (an approximation of balloon help).

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

which may be updated from time-to-time. GAIA is available for download as part of JAC Starlink Release at:

#### 2.1 Using GAIA from the C-shell

To display an image in GAIA use the following command (assuming that you are already initialized to use Starlink software):

% gaia image_name

Alternatively you can use the File menu to load an image.

If you want to display an image in an existing GAIA then use the invocation:

You can also write to a specific window using the clone number:

This displays into the window with title GAIA::SkyCat (2). If this window doesn’t exist it will be created.

A list of images can be displayed in GAIA using the command:

% gaiadisp image_name1 image_name2 image_name3 ...

These will be displayed in separate clones. Finally percentile or data cuts can be applied using the -p option or -l and -h options:

% gaiadisp -p 98 image_name1 image_name2 image_name3 ...

% gaiadisp -l 100 -h 200 image_name1 image_name2 image_name3 ...

(works for the single image case too).