eROSITA is an X-ray instrument built by the Max Planck Institute for Extraterrestrial Physics in Germany. It is part of the Russian–German Spektr-RG space observatory, which also carries the Russian telescope ART-XC. From Wikipedia
The black hole in galaxy SDSS1335+0728 exhibits quasiperiodic eruptions every 4.5 days, challenging existing astrophysical theories.
