History and specifics
The singers were notable for performing Alphaurian opera. The style of performance was unusual in that it involved singing between keys.
In 2266, when the opera company toured Earth, Nyota Uhura hoped to see a performance during shore leave. She invited Hikaru Sulu, but he disliked the style and hoped it was sold out. (TOS comic: "Furlough to Fury")
- The homeworld of the touring company was unspecified. It could be Centaurus or one of several other worlds in the Alpha Centauri system.