NSO/GONG The GONG Network of Sites

On February 5, 1991, the GONG Site Selection Committee Report concluded a site survey of fifteen candidate sites and selected six sites that comprise the GONG network. Each site represents one of the six longitudal bands that allows the network to make 24-hour a day observations of the Sun.

The six sites comprising the GONG Network are:

• The Big Bear Solar Observatory in California, USA.
• The Mauna Loa Observatory in Hawaii, USA.
• The Learmonth Solar Observatory in Western Australia.
• The Udaipur Solar Observatory in India.
• The Observatorio del Teide in the Canary Islands.
• The Cerro Tololo Interamerican Observatory in Chile.

Here is the current time at the GONG sites and some other interesting places on the Earth.

Here are links to on-line weather sites.

Here are the dates that the sites were down due to preventative maintenance.

Here are the latitude, longitude and elevations of the sites. The data is actually the location of the GPS antennas.

This is an image map, click the map location to find more info about any specific site:

The measured performance "fill factor" of the GONG site survey network was better than 93%. Current coverage with the network is around 87%. This is less than the site survey fill factor because more stringent criteria is used to select good data samples and semiannual preventive maintenance visits to each site bring down the instrument for about ten days per visit.

The site survey used small pyrheliometers as the survey instrument. An important measure of performance of the network is the spectrum of the observing window function. Significantly, the power spectrum of the site survey data showed a suppression of the fundamental 1/day sidelobe by a factor of more than 400, of all sidelobes (fundamental plus harmonics) by a factor of over 200, and of background noise by a factor of nearly 50. More information can be found in the site survey papers:

Hill, et al. " The Global Oscillation Network Group Site Survey. I. Data Collection and Analysis Methods", Solar Physics 152, 321 - 349
Hill, et al. " The Global Oscillation Network Group Site Survey. II. Results", Solar Physics 152, 351 - 379.

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