The Sonnia planet/system is causing me a bit of confusion. It was picked up back in 2011 as being present on the 2571 map of the Federated Suns given in Handbook: House Davion, but not on the 2571 map given in Handbook: House Liao, which Øystein confirmed
here was a mistake in Handbook: House Davion.
Handbook: House Davion (page 54) and Handbook: House Liao (page 31) both show Sonnia on the maps for 2822. This is contradicted by First Succession War, which doesn't show Sonnia on the 2786 inner sphere map (page 25), or the Capellan/FedSuns border map (page 92) or the 2822 inner sphere map (page 113). Sonnia also isn't on the 2822 inner sphere map in Historical: Liberation of Terra Volume 2 (page 122).
Era Report: 2750 doesn't show Sonnia on the 2750 map of the inner sphere (page 37), nor is it on the 2765 map of the inner sphere in Historical: Liberation of Terra Volume 1 (page 11) or the 2765 map of the Federated Suns in 2765 in Field Report 2765: AFFS (page 29).
Sonnia doesn't show up in any of the maps in Field Manual: SLDF, but is specifically mentioned by name in the write of the SLDF IX Corps (page 48) as being the world the Seventy-sixth Royal Dragoon Regiment is based on, and has been for a while:
The Spirit of ’76 received its name due to its number and the fact that many of its officers and enlisted originated from the New York and Pennsylvania areas of North America on Terra. Deployed on the tropical world of Sonnia, the Spirit of ’76 sees far less movement and redeployment than the rest of the IX Corps. The Seventy-sixth Royal Dragoons are used as a garrison force at the uranium mining areas and refinement facilities on Sonnia. The Seventy-sixth’s presence ensures that the produced uranium is properly secure.
While Sonnia isn't on any of the maps in First Succession War, it is specifically mentioned on page 81 (being conquered by the Confederation), on page 87 (JumpShips from Sonnia are rerouted to Kentares IV to evacuate military forces) and on page 135 as the 2821 location of the 1st Ariana Fusiliers and 8th Chesterton Cavalry.
So... what's up with Sonnia? I'm not sure if it's a system that was colonised in the Star League era, but got left off the maps by accident - and that's then perpetuated through the maps in the subsequent books, perhaps?
