Star Trek: Challenger is a spin-off series of Star Trek novels published by Pocket Books in the United States as part of Pocket’s line. Based on the titular TV series created by Gene Roddenberry, the series was created by Pocket editor John J. Ordover and writer Diane Carey, and was a continuation of the six-book storyline, Star Trek: New Earth. The sixth and final New Earth book was subtitled Challenger, and served as a springboard for Star Trek: Challenger. It was published on August 1, 2000.

https://en.wikipedia.org/wiki/Star_Trek:_Challenger