We analyze 3 { \farcs } 5 resolution , high sensitivity radio continuum images of the nearby spiral galaxy NGC 4258 at 6 and 20 cm derived from multiple observations used to monitor the radio supernova SN 1981K ( Van Dyk et al .
1992 , [ ApJ , 396 , 1995 ] ) .
Seven bright H II region and five supernova remnant candidates are identified .
Extinctions to the H II regions are estimated for the first time from a comparison of radio flux densities to new optical fluxes derived from H \alpha observations by Dutil & Roy ( 1999 , [ ApJ , 516 , 62 ] ) .
The bright end of the H II region luminosity function is established at each wavelength .
The luminosity functions are best fit by power laws consistent with the shape of previously published radio and optical luminosity functions for a number of galaxies .
The supernova remnants are all about 2–3 times the radio luminosity of Cas A .
In addition , the galaxy ’ s nucleus is shown to have been variable over the SN 1981K monitoring period .
The spectral index ( \alpha ) distribution of the anomalous radio arms is investigated and found to be relatively uniform at \alpha = -0.65 \pm 0.10 .