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THE discovery1 of a very small diameter radio source with a very flat spectrum at the centre of the galactic supernova remnant G127.1 + 0.5 has stimulated much interest2–4. Because the central source has unusual properties, and because the a priori probability of finding such an object at the very centre of a supernova remnant is exceedingly low, Caswell1 suggested that the central radio source might be emanating from the collapsed stellar remnant of the supernova that produced the surrounding shell of radio emission. This intriguing idea was pursued by Salter, Pauls and Halsam3 who showed that the extended supernova remnant is perfectly normal in shape and in radio spectrum, while the central source has a spectrum that is flat from 3 to 15 GHz at a flux density of 0.5 Jansky. A long-baseline interferometric measurement by Shaffer et al.4 at 10.65 GHz showed that the angular size of the central source is about 0.0005 arcs. We now present evidence from direct optical observation suggesting that the link between the central source and the supernova remnant is purely circumstantial.

The central source in the supernova remnant G127.1 + 0.5