SN 2018cow (ATLAS name: ATLAS18qqn; also known as Supernova 2018cow, AT 2018cow (AT = Astronomical Transient), and "The Cow") was a very powerful astronomical explosion, 10–100 times brighter than a normal supernova, spatially coincident with galaxy CGCG 137-068, approximately 200 million ly (60 million pc) distant in the Hercules constellation. It was discovered on 16 June 2018 by the ATLAS-HKO telescope, and had generated significant interest among astronomers throughout the world. Later, on 10 July 2018, and after AT 2018cow had significantly faded, astronomers, based on follow-up studies with the Nordic Optical Telescope (NOT), formally described AT 2018cow as SN 2018cow, a type Ib supernova, showing an "unprecedented spectrum for a supernova of this class"; although others, mostly at first but also more recently, have referred to it as a type Ic-BL supernova. An explanation to help better understand the unique features of AT 2018cow has been presented. AT2018cow is one of the few reported Fast Blue Optical Transients (FBOTs) observed in the Universe. In May 2020, however, a much more powerful FBOT than AT2018cow (namely, CRTS-CSS161010 J045834-081803, or CSS161010 for short) was reportedly observed. On 2 November 2018, two independent teams of astronomers both concluded that the AT 2018cow event was "either a newly formed black hole in the process of accreting matter, or the frenetic rotation of a neutron star." In January 2019, astronomers proposed that the explosion may have been a white dwarf being pulled apart by a black hole; or a supernova leaving behind a black hole or a neutron star, the creation of a compact body being observed for the first time. On 13 December 2021, astronomers reported that AT 2018cow, an extreme FBOT, "could be a neutron star or black hole with a mass less than 850 solar masses" based on high-time-resolution X-ray observation studies.

Data from the Hubble Space Telescope MAST Pipeline. Release date: 2022-09-30

Camera: WFC3
Color Mapped:
Red-F814W
Green-F555W
Blue-F555W

Processed with FITS Liberator, PixInsight and Photoshop 2022