Celtris III was the uninhabited third planet in its star system. The lynar, a type of Celtran bat, was indigenous to this planet. This system was located in Cardassian space, near the Federation-Cardassian border.
In 2369, Starfleet Intelligence began monitoring bursts of theta-band subspace emissions from Celtris III, which typically indicate a metagenic device in operation. Since such devices were illegal, this led Starfleet to believe that the Cardassians might have been operating a secret research lab somewhere beneath the planet's surface. However, the signal was faked just to lure Captain Jean-Luc Picard to the planet, who was an expert in theta emissions. During a secret mission on Celtris III, Picard was taken into custody and interrogated by Gul Madred. (TNG: "Chain of Command, Part I", "Chain of Command, Part II")