This work utilizes data obtained by the Global Oscillation Network Group (GONG) project, managed by the National Solar Observatory, a Division of the National Optical Astronomy Observatories, which is operated by AURA, Inc. under a cooperative agreement with the National Science Foundation. The data were acquired by instruments operated by the Big Bear Solar Observatory, High Altitude Observatory, Learmonth Solar Observatory, Udaipur Solar Observatory, Instituto de Astrofísica de Canarias, and Cerro Tololo Interamerican Observatory. We are thankful to S. Tomczyk and J. Schou for sending us the LOWL results of their analysis. We are also thankful to Anette Skovgaard and Kyla Hanington for proofreading the English. The work was supported in part by the Danish National Research Foundation through its establishment of the Theoretical Astrophysics Center.
© European Southern Observatory (ESO) 1999
Online publication: April 28, 1999