Cutouts of the source W51 d4e and its SED. The red circle shows the source aperture used to measure the peak and total flux density. The red line shows a 1′′scalebar. The Epochs are indicated as E1, E2, and E3. In the SED plot, the dark and light red show the 1σ and 3σ noise levels. The SED plot is shown twice, first linear-linear, and second linear-log. Green points are from Epoch 1, blue points are Epoch 2, and red points are Epoch 3. Squares show the peak flux density, circles show the ‘background-subtracted’ flux density – i.e., the peak minus the minimum value in the map. The dotted curve shows a linear SED (S_ν ∝ ν) and the dashed shows a power-law curve with α = 2, i.e., S_ν ∝ ν². Both curves are normalized to go through the 12.1 GHz Epoch 2 data point. In this case, all of the Epoch 1 (green) points are within the noise, while all of the Epoch 2 and 3 (blue and red) points are detected at >5σ below 15 GHz.