l–ν diagrams of the low-frequency modes with 1 ⩽ l ⩽ 25 measured in 2088 days of GONG (left panel) and MDI data (right panel). The open circles represent the modes measured by Korzennik (2005) using a classic peak-fitting method of the individual- m spectra, while the red dots correspond to the additional modes measured using the m-averaged spectrum technique that were not observed by Korzennik (2005). The ridges of same radial order are also indicated from n = 2 to n = 12.