New 1.4 GHz VLA observations of the pulsar-powered supernova remnant 3C 58 have resulted in the highest-quality radio images of this object to date .
The images show filamentary structure over the body of the nebula .
The present observations were combined with earlier ones from 1984 and 1991 to investigate the variability of the radio emission on a variety of time-scales .
No significant changes are seen over a 110 day interval .
In particular , the upper limit on the apparent projected velocity of the wisp is 0.05 c .
The expansion rate of the radio nebula was determined between 1984 and 2004 , and is 0.014 \pm 0.003 % yr ^ { -1 } , corresponding to a velocity of 630 \pm 70 km s ^ { -1 } along the major axis .
If 3C 58 is the remnant of SN 1181 , it must have been strongly decelerated , which is unlikely given the absence of emission from the supernova shell .
Alternatively , the low expansion speed and a number of other arguments suggest that 3C 58 may be several thousand years old and not be the remnant of SN 1181 .