THE GLOBAL OSCILLATION NETWORK GROUP SITE SURVEY .2. RESULTS

The Global Oscillation Network Group (GONG) Project will place a netwo rk of instruments around the world to observe solar oscillations as co ntinuously as possible for three years. The Project has now chosen the six network sites based on analysis of survey data from fifteen sites around the world. The chosen sites are: Big Bear Solar Observatory, C alifornia; Mauna Loa Solar Observatory, Hawaii: Learmonth Solar Observ atory, Australia; Udaipur Solar Observatory, India; Observatorio del T eide, Tenerife; and Cerro Tololo Interamerican Observatory, Chile. Tot al solar intensity at each site yields information on local cloud cove r, extinction coefficient, and transparency fluctuations. In addition, the performance of 192 reasonable networks assembled from the individ ual site records is compared using a statistical principal components analysis. An accompanying paper describes the analysis methods in deta il; here we present the results of both the network and individual sit e analyses. The selected network has a duty cycle of 93.3%, in good ag reement with numerical simulations. The power spectrum of the network observing window shows a first diurnal sidelobe height of 3 x 10(-4) w ith respect to the central component, an improvement of a factor of 13 00 over a single site. The background level of the network spectrum is lower by a factor of 50 compared to a single-site spectrum.