For other uses, see
Acamar (also known as Theta Eridani) is a  star system composed of two class A stars that appear as one when viewed from Earth, 120 or so light-years away. ( ST website: )
StarTrek.com lists Acamar as being "50-60 light-years from Sol." The Last Unicorn RPG module: Planets of the UFP indicates that the Acamar system has only one star.
2275, the USS was en-route to the Acamar system, before the starship was ambushed by eight Enterprise Klingon battlecruisers. ( TOS novel: )
The Wounded Sky
2366, the USS entered the system to track down the Enterprise-D Gatherers, a group of Acamarians that had attacked several Federation outposts. ( TNG episode: " The Vengeance Factor")
2374, Sovereign Marouk promoted membership in the Federation. ( Last Unicorn module: )
Planets of the UFP
Commander Tuvok of the USS investigated the Titan Borg attacks of 2381, he noticed that they had all occurred on the border between the Federation and the Klingon Empire, stretching between the Acamar and Ramatis systems. ( - ST Destiny novel: )
Gods of Night
February of that year, a fleet of Borg cubes coming from the Azure Nebula targeted every inhabited system on their way to Earth, and laid waste to Acamar III. ( ST novel: )
A Singular Destiny
Star chart showing Acamar.
2368, Theta Eridani was home to the unaligned  Acamarian people. ( TNG episode: " The Vengeance Factor")
2378, the system was in or near Federation territory, in the general vicinity of the Azure Nebula. ( ST reference: )
2409, the Acamar system remained independent but was surrounded by territory claimed and patrolled by the fledgling Romulan Republic. In that year, Subcommander Mivek asked the Romulan Republican Force and the allied partners to patrol the system. ( - STO New Romulus mission: " Tau Dewa Sector Patrol (Daily)")
The patrol mediated between the Acamarian clan leader and the Acamarian clan rebel. The rebel complained about some clans being pushed to the
moons and outer planets of the system for operations. A Tal Shiar squadron revealed itself upon the successful mediation when they failed to instigate internecine conflict, and the Acamarians and Allies defeated the agitators. ( - STO Tau Dewa Sector Patrol (Daily) mission: " Acamar System Patrol")
Stars, systems and objects of the Eridanus constellation
1 Eridani (Tau-1 Eridani) • 3 Eridani (Azha, Eta Eridani) • 13 Eridani (Zibal, Zeta Eridani) • 14 Eridani • 18 Eridani (Delta Orcus, Toredar, Epsilon Eridani) • 23 Eridani (Rana, Delta Eridani) • 34 Eridani (Gamma Eridani, Zaurak) • 38 Eridani (Beid, Omicron-1 Eridani) • 40 Eridani (Keid, Omicron-2 Eridani, Vulcanis) • 59 Eridani • 67 Eridani (Cursa, Beta Eridani) • 82 Eridani • 88 Eridani • 198 Eridani • Alpha Eridani (Achernar) • Beta Eridani (Cursa, 67 Eridani) • Chi Eridani (Caleb, Kaleb) • Delta Eridani (Rana, 23 Eridani) • Epsilon Eridani (Delta Orcus, Toredar, 18 Eridani) • Eta Eridani (Azha, 3 Eridani) • Gamma Eridani (34 Eridani, Zaurak) • Iota Eridani • Omicron-1 Eridani (Beid, 38 Eridani) • Omicron-2 Eridani (Keid, 40 Eridani, Vulcanis) • p Eridani • Tau-1 Eridani (1 Eridani) • Tau Eridani Cloud • Theta Eridani (Acamar) • Zaurak (34 Eridani, Gamma Eridani) • Zeta Eridani (Zibal, 13 Eridani)
history or specifics are established for this location in gameplay. The system name of Acamar was part of a list that were applied to systems on the game map, with random attributes assigned to them. In Starfleet Command III TNG video game: , the orbital configuration of the game map star systems was randomly generated each time a new game started.
Birth of the Federation