Discovery of radio pulsations from the X-ray pulsar J0205+6449 in supernova remnant 3C 58 with the Green Bank Telescope

We report the discovery with the 100 m Green Bank Telescope of 65 ms radio pulsations from the X-ray pulsar J0205+6449 at the center of supernova remnant 3C 58, making this possibly the youngest radio pulsar known. From our observations at frequencies of 820 and 1375 MHz, the free-electron column density to PSR J0205+6449 is found to be 140.7 +/- 0.3 cm(-3) pc. The barycentric pulsar period P and period derivative (P) over dot determined from a phase-coherent timing solution are consistent with the values previously measured from X-ray observations. The averaged radio profile of PSR J0205+6449 consists of one sharp pulse of width approximate to3 ms approximate to0.05P. The pulsar is an exceedingly weak radio source, with a pulse-averaged flux density in the 1400 MHz band of similar to45 muJy and a spectral index of similar to-2.1. Its radio luminosity of similar to0.5 mJy kpc(2) at 1400 MHz is lower than that of similar to99% of known pulsars and is the lowest among known young pulsars.