What supernova remnant is one component of the Sagittarius A radio source?

The supernova remnant that forms one component of the Sagittarius A radio source is Sagittarius A East.

Sagittarius A is not a single object but a complex radio-emitting region at the Milky Way’s center. Its three overlapping components are Sagittarius A East, a supernova remnant; Sagittarius A West, a spiral-shaped structure of ionized gas; and Sagittarius A*, the compact radio source associated with the central supermassive black hole.

Sagittarius A East is about 27 light-years across and lies approximately 7 light-years from Sagittarius A*. Evidence indicates that it formed from an explosion between about 1,000 and 10,000 years ago. Its radio shell and X-ray-emitting interior have been shaped by interaction with the exceptionally dense interstellar environment around the Galactic Center.

The most frequent confusion is between Sagittarius A East and Sagittarius A*. The asterisk does not mean a supernova remnant: it identifies the compact source marking the position of the Milky Way’s central black hole. Sagittarius A West is also not a remnant; it is an ionized-gas structure inside the larger radio complex.