The control panel in the lower left frame allows you to choose the target field, the update mode, the navigation image resolution, and the help text.
The default update mode is to update the high resolution image on mouse clicks only. This is best for slow connections. With a fast connection you can chose to have the high resolution image update continuously, or you can have the update take place only after the mouse has remained still for about 1 second. Image sizes vary somewhat with content, but are on the order of 50 kbytes per 600 x 600 high resolution image.
Celestial coordinates (J2000) of the field center are shown under the high resolution image.
The default navigation image size is 600 x 600, but you can choose a higher resolution of 1200 x 1200 in which you can scroll around. The high resolution image size is fixed at 600 x 600 pixels. The default image size works well with a 1000 x 1260 monitor if the browser is expanded to fill the screen.
Nick Kaiser, Dec 1998