We present 33 GHz imaging for 112 pointings towards galaxy nuclei and extranuclear star-forming regions at \approx 2″ resolution using the Karl G. Jansky Very Large Array ( VLA ) as part of the Star Formation in Radio Survey .
A comparison with 33 GHz Robert C. Byrd Green Bank Telescope single-dish observations indicates that the interferometric VLA observations recover 78 \pm 4 \% of the total flux density over 25″ regions ( \approx kpc-scales ) among all fields .
On these scales , the emission being resolved out is most likely diffuse non-thermal synchrotron emission .
Consequently , on the \approx 30 - 300 pc scales sampled by our VLA observations , the bulk of the 33 GHz emission is recovered and primarily powered by free-free emission from discrete H ii regions , making it an excellent tracer of massive star formation .
Of the 225 discrete regions used for aperture photometry , 162 are extranuclear ( i.e. , having galactocentric radii r _ { G } \geq 250 pc ) and detected at > 3 \sigma significance at 33 GHz and in H \alpha .
Assuming a typical 33 GHz thermal fraction of 90 % , the ratio of optically-thin 33 GHz-to-uncorrected H \alpha star formation rates indicate a median extinction value on \approx 30 - 300 pc scales of A _ { H \alpha } \approx 1.26 \pm 0.09 mag with an associated median absolute deviation of 0.87 mag .
We find that 10 % of these sources are “ highly embedded ” ( i.e. , A _ { H \alpha } \gtrsim 3.3 mag ) , suggesting that on average H ii regions remain embedded for \lesssim 1 Myr .
Finally , we find the median 33 GHz continuum-to-H \alpha line flux ratio to be statistically larger within r _ { G } < 250 pc relative the outer-disk regions by a factor of 1.82 \pm 0.39 , while the ratio of 33 GHz-to-24 \mu m flux densities are lower by a factor of 0.45 \pm 0.08 , which may suggest increased extinction in the central regions .