2008MNRAS.390..235S

PSR J0205+6449 is an X-ray and radio pulsar in supernova (SN) remnant 3C 58. We report on observations of the central region of 3C 58 using the 4.2-m William Herschel Telescope at the Isaac Newton Group of Telescopes, La Palma, with the intention of identifying the optical counterpart of PSR J0205+6449 and characterizing its pulsar wind nebula (PWN). Around the pulsar position, we identified extended emission with a magnitude of B = 23.97 ±0.10mag, V = 22.95 ±0.05mag and R = 22.15 ±0.03mag consistent with a PWN. From the R-band image, we identified three knots with m_R= 24.08±0.07mag (o1), 24.15±0.07mag (o2) and 24.24±0.08mag (o3). We confirm the presence of an optical PWN around PSR J0205+6449 and give an upper limit of m_R~ 24 for the optical magnitude of the pulsar. Furthermore, we make the tentative suggestion that our object o1, with an m_R~ 24.08, is the optical counterpart. If confirmed, the pulsar would have an L_R/L_X~ 0.004 and an optical efficiency of about five per cent of the Crab pulsar. Such a low efficiency is more consistent with the characteristic age of the pulsar rather than that of SN 1181.