NGC 3982 (also known as UGC 6918) is an intermediate spiral galaxy approximately 68 million light-years away in the constellation Ursa Major.

It harbors a supermassive black hole at its core and has massive regions of star formation in the bright blue knots in the spiral arms.

It is helpful because it possesses two tools used to estimate astronomical distances: supernovae and Cepheid variable stars.

In 1998, the light from a supernova in NGC 3982 (later called SN 1998aq) reached Earth and was discovered by British amateur astronomer Mark Armstrong.

When the white dwarf had gathered enough mass and was no longer able to support itself, the star detonated in a violent and extremely bright explosion.