systematic observations of the sun at many astronomical observatories of the world for the purpose of collecting data on all manifestations of solar activity. The solar survey program includes observations of the photosphere in white light and the chromosphere in the light of the hydrogen Hα line with photosphere-chromosphere telescopes equipped with interference-polarization filters. Many observatories carry out measurements of magnetic fields and sunspots by means of large telescopes with spectrographs. Observatories located on high mountains use coronagraphs to make daily observations of the solar corona. A number of stations record the sun’s radio-frequency radiation with radio telescopes. Data on the sun’s X-radiation are obtained by equipment in artificial earth satellites.
In the USSR, the solar survey includes about 20 observatories, which carry out observations of the sun for 12 hours daily. The results of observations made at solar survey stations in the USSR and several other countries are published in the monthly bulletin Solnechnye dannye (Solar Data) published by the Pulkovo Observatory. The bulletin provides a daily depiction of the sun showing all visible spots, filaments, flocculi, and prominences and the surrounding corona. Tables are presented giving information on spots, filaments, solar radio emission, and magnetic fields.
The Soviet solar survey is part of a world network of stations. The three world centers for the collection of solar data are located in the USSR, the USA, and France. Several international catalogs of solar activity are published. By international agreement, all observatories report the appearance of major flares to the world centers immediately after the flares are detected. Some observatories send the results of their measurements of magnetic fields and spots to the Meudon Observatory in France, where a daily forecast of solar activity is made. In the 1950’s and 1960’s cooperative worldwide research programs were organized within the framework of the international solar survey. They included the International Geophysical Year (1957-58), the International Year of the Quiet Sun (1964–65), and a number of limited programs, such as the proton-flare program.
The data obtained by the world network of solar survey stations are used to solve scientific problems of the physics of the sun, earth, and interplanetary space and to meet practical needs, such as the forecasting of radio-wave propagation conditions and magnetic storms. Weather forecasts also take the data into account.
N. N. STEPANIAN [23–1760–]