The Radio Spectral Index and Expansion of 3 C 58

We present new observations of the plerionic supernova remnant 3C 58 with the VLA at 74 and 327 MHz. In addition, we re-reduced earlier observations at 1.4 and 4.9 GHz taken in 1973 and 1984. Comparing these various images, we Ðnd that (1) the remnant has a Ñat and relatively uniform spectral-index distribution, (2) any expansion of the remnant with time is signiÐcantly less than that expected for uniform, undecelerated expansion since the generally accepted explosion date in 1181 A.D., and (3) there is no evidence for a nonthermal synchrotron-emission shell generated by a supernova shock wave, with any such emission having a surface brightness of less than 1 ] 10~21 W m~2 Hz~1 sr~1 at 327 MHz. Subject headings : ISM: individual (3C 58) È radio continuum: ISM È supernova remnants