Starbase 137

From Memory Alpha, the free Star Trek reference.

Starbase 137 is a Federation starbase administered by Starfleet.

When Benjamin Sisko was a sophomore at Starfleet Academy, he performed his field study at this Starbase. He was "a little apprehensive" upon arriving, but later came to regard his time there as one of the best experiences of his life. (DS9: "The Ascent")