Beta Capricus

From Memory Alpha, the free Star Trek reference

Beta Capricus is an interesting celestial feature once erroneously believed by Earth researchers to be a star. In reality, Beta Capricus was only an electromagnetic echo of a distant galaxy. This was not known, however, until 2210 when a Earth starship was sent, with crew in stasis, on a six-month deep space mission to explore the presumed location of the star only to find, in fact, that there was nothing there. (VOY: "11:59")