Autoguiding By Imager

Isn’t it a GoTo telescope is capable of tracking celestial objects? Why do I need the autoguiding? $:-\$

At first, tracking is just similiar to guiding. For instance in the Autostar Suite from Meade, tracking allows you to define a bright spot (centroid) that it (Autostar Suite) will use to anchor images when combining (stacking) them into one image.

In autoguiding, the system keeps the centroid anchored mechanically by slowing or speeding the drive motors: i.e. do drive corrections automatically if the guide star moves out of position for any reason. In order to use autoguiding, you must have built in autoguiding circuitry in your telescope to work together with the autoguiding ready imager.

Okay now, back to the main topic, why do we need autoguiding? It is needed only for long exposures on faint deepsky objects, to correct slow drifts caused by gear periodic error, mount flexures and such.