It has recently been suggested that the radio spectrum of the Galactic supernova remnant HB 3 shows flattening at higher frequencies ( above about 1 GHz ) .
Here I review the radio spectrum of HB 3 , noting the difficulties in deriving accurate flux densities for this remnant , particularly at high frequencies , due to the proximity of bright , thermal emission from W3 and its surroundings .
A flux density for HB 3 at 2695 MHz is derived from Effelsberg survey data .
The spectrum of HB 3 is well represented by a simple power-law spectrum from 22 to 2695 MHz , with a spectral index of 0.56 \pm 0.03 .
It is concluded that contamination with thermal emission from adjacent regions is the cause for the reported spectral flattening of HB 3 .