Galactic Roundel

The Insignia of Unity was an eight-rayed stelar symbol centered in a circle whose circumference was made up of dashed lines. Also known as the Emblem of the Galactic Republic or the Republic insignia, the Insignia of Unity was the seal of the Galactic Republic.

History
The Insignia of Unity dates back thousands of generations and the Bendu monks' who studied numerology. In their study they believed that the number nine signified the beneficent presence of the Force in a united galaxy. The Insignia of Unity was meant to represent the number nine with it's eight spokes joined to one disc. Eventually-since the Jedi were founded from the Bendu and the Jedi Order had always been close to the Republic-the Insignia of Unity was adopted to become the symbol of the Galactic Republic.

In 25,000 BBY a reduced form of the Jedi/Bendu-inspired symbol was used by the Republic during the Unification Wars.

During the Old Sith Wars the Republic was using a nine-spoke symbol and putting it on there ships.

Later on the Insignia of Unity itself once again had become the symbol of the Republic and unity. One was placed on the podium of the Galactic Senate Rotunda and up until Palpatine's proclamation one adorned the Hall of Justice on Alderaan.

In 25 BBY the Rotunda had undergone a desperate renovation at which point the emblem that sat on the podium was replaced by a counterfeit. The counterfeit was placed by the Republic Group who believed the symbol could be used to reawaken and rouse those who had fallen under Palpatine's sway. The Republic Group had the symbol moved to Tandun III for safe keeping.

During the Clone Wars numerous Republic vehicles and vessels were marked with the Insignia of Unity. Some vessels included the Republic Gunship and the UT-AT.