The Global Oscillation Network Group (GONG) is a community-based project to conduct a detailed study of solar internal structure and dynamics using helioseismology. In order to exploit this new ... technique, GONG has developed a six-station network of extremely sensitive, and stable velocity imagers located around the Earth to obtain nearly continuous observations of the SUN's "five-minute" oscillations, or pulsations.
The site comprising the GONG Network are:
Big Bear, California
Cerro Tololo, Chile
Mauna Loa, Hawaii
Observatorio del Teide, Canary Islands
The five-minute oscillation is a subtle effect. Individual modes may exhibit velocities of less than 0.2 meters/second, while the sum of all of the modes is only a few hundred meters/second. The ultimate intention is to have the measurements be limited by the Sun's ``random'' surface motions. This means developing six stable instruments capable of making imaged velocity measurements with a precision of significantly less than one meter/second - one part in ten million! A low technological risk instrument based on a Michelson interferometer was selected, and it will be supported by a highly automated, portable installation, somewhat reminiscent of a spacecraft experiment.
Each station in the network will produce more than 200 megabytes of data every day. Over the three year observing run, the raw data will exceed one terabyte, and the various processed data sets will exceed this several-fold. To keep up with the data flow, a pipe-line capable of roughly 6 Megaflops has be established to do the bulk processing and provide subsets of the data for the scientific community. Because of the widespread scientific participation, distributed data, software and analysis tools will be provided. Thus, in addition to a central facility, participating scientists will have access to readily transportable data archives and software, as well as shared analysis programs at their home institutions.