Gong Spectra in Three Observables: What is a P-Mode Frequency?

Extract

The Global Oscillation Network Group (GONG) is an international, community-based helioseismology project conducting a detailed study of the internal structure and dynamics of the Sun. GONG is operating a six-station network of full-disk solar imagers exploring the range from ℓ = 0 to about ℓ = 200. Full network operation began in October 1995. The observation duty cycle has averaged about 87% over the first 684 days of full operation, and single-site data loss due to instrument down time is less than 2%. The data management group is processing the network data at pace with the collection rate. Here we present a comparison of spectra obtained in Doppler velocity, total spectral intensity, and modulation (a mixture of equivalent width and magnetic field strength).