Earth-orbiting satellites Uhuru and Chandra X-ray Observatory have detected two bright X-ray sources in this cluster: Messier 15 X-1 (4U 2129+12) and Messier 15 X-2.
Satelit bumi Uhuru dan observatorium sinar X Chandra mendeteksi dua sumber sinar X di dalam gugus ini: Messier 15 X-1 (4U 2129+12) dan Messier 15 X-2.