This tool is to control the connection to the planetarium.
It is used to display an astrometry resolved image with the right click menu, or to set the targets coordinates in the sequence preparation.
If you configure to start the planetarium you can directly click the Connect button. Otherwise be sure the planetarium application is running before to click it.
In previous version of the program there was a button here to slew to a target selected in the planetarium. This function is now integrated in the telescope mount Goto button.