How Thrawn Met Palpatine for the First Time [Canon] – Star Wars Explained

The first time Palpatine and Thrawn met.

In the beginning of Heir to the Empire, Thrawn explains to Pellaeon that Palpatine used The Force to guide the Imperial military. This means that Thrawn, unlike most Admirals, knew that Palpatine was a Force-user. How did he learn this? Did he also know that Palpatine was «Darth Sidious» and was behind the Trade Federation and Dooku? Did he also know that Vader was Anakin?