This paper presents observations of Cygnus A at 74 and 327 MHz at angular resolutions of approximately 10″ and 3″ , respectively .
These observations are among the highest angular resolutions obtained below 1000 MHz for this object .
While the angular resolution at 74 MHz is not sufficient to separate clearly the hot spots from the lobes , guided by 151 and 327 MHz images , we have estimated the 74 MHz emission from the hot spots .
We confirm that the emission from both the western and eastern hot spots flattens at low frequencies and that there is a spectral asymmetry between the two .
For the eastern hot spot , a low-energy cutoff in the electron energy spectrum appears to explain the flattening , which implies a cutoff Lorentz factor \gamma _ { \mathrm { min } } \approx 300 , though we can not exclude the possibility that there might be a moderate level of free-free absorption .
For the western hot spot , the current observations are not sufficient to distinguish between a free-free absorped power-law spectrum and a synchrotron self-absorbed spectrum .