Left column: l–ν diagram, and a ₁, a ₃, and a ₅ splitting coefficients for the common, low-frequency p-modes measured in the 3960 day GONG data set obtained by using the maximum likelihood (circles) and the narrowest peak (dots) of the m-averaged spectrum as FOM to determine the best estimates of the a-coefficients (see Section 3.1 and Figure 1). Right column: associated 1σ formal uncertainties (nHz) of the mode central frequencies, and of the a ₁, a ₃, and a ₅ splitting coefficients.