https://www.theregister.co.uk/2018/06/14/supernova_magnetic_field_research/

How to measure a magnetic field that's very long way away, and is very, very weak. An international group of boffins have announced that they figured out how.

The magnetic field in question belongs to a distant supernova remnant, Supernova 1987A, 168,000 light years from Earth. While the supernova exploded in 1987, its remnants remains a favourite observation target.