Using NASA’s Swift space telescope and NICER instrument aboard the International Space Station (ISS), astronomers have investigated the properties of an ultra-luminous X-ray pulsar known as NGC 300 ULX1. Results of this study, presented in a paper published May 9 on the arXiv preprint server, indicate that this object experienced an unprecedented spin evolution as its spin period decreased significantly during a timespan of four years.
Source:
https://phys.org/news/2019-05-ultra-luminous-x-ray-pulsar-ngc-ulx1.html