Tight system of black holes in a distant galaxy
An international research team, including Hans-Rainer Klöckner from the Max Planck Institute for Radio Astronomy in Bonn, Germany, performed VLBI (Very Long Baseline Interferometry) observations with radio telescopes at a number of frequencies to discover the inner two black holes of the triple system. The VLBI technique combines the signals from large radio antennas separated by up to 10. 000 kilometres to see details 50 times finer than that possible with the Hubble Space Telescope. In this project the Effelsberg 100m radio telescope took part in European VLBI network (EVN) observations covering two radio frequencies.