NGC 4567 and NGC 4568

NGC 4567 and NGC 4568 are a set of unbarred spiral galaxies about 60 million light-years away in the constellation Virgo. They were both discovered by William Herschel in 1784. They are part of the Virgo Cluster of galaxies.
These galaxies are in the process of colliding and merging with each other, as studies of their distributions of neutral and molecular hydrogen show, with the highest star-formation activity in the part where they overlap. However, the system is still in an early phase of interaction. In about 500 million years the galaxies will coalesce into a single elliptical galaxy.

Supernovae

Four supernovae have been observed in the Butterfly Galaxies:SN 1990B was discovered by Saul Perlmutter and Carlton Pennypacker on 20 January 1990.SN 2004cc was discovered by the Lick Observatory Supernova Search on 10 June 2004.SN 2020fqv was discovered by the Automatic Learning for the Rapid Classification of Events on 31 March 2020.SN 2023ijd was discovered by All [Sky Automated Survey for SuperNovae|ASAS-SN] on 14 May 2023.

Naming controversy

The two galaxies were nicknamed "Siamese Twins" because they appear to be connected. On August 5, 2020, NASA announced that they would not use that nickname in an effort to avoid systemic discrimination in their terminology.