NGC 4051 is an intermediate spiral galaxy in the constellation of Ursa Major.

[5] NGC 4051 contains a supermassive black hole with a mass of 1.73 million M☉.

[6] This galaxy was studied by the Multicolor Active Galactic Nuclei Monitoring 2m telescope.

However, in early 1998 the X-ray emission ceased as observed by the Beppo-SAX satellite.

X-ray emission had risen back to normal by August 1998.