Three times a day, the measurement is transmitted from the Dominion Radio Astrophysical Observatory to the National Research Council to a list of recipients worldwide.
Some use it directly; others archive it and make it available on their websites, along with other data.
Measurements are made using two small radio telescopes called “flow monitors”. The data consist of measurements of the intensity of solar radio radiation at a wavelength of 10.7 centimeters. It is used by those who participate in activities in which, in one way or another, they are affected by what the sun does. These include communication services, space mission managers and various infrastructure services.
The data is known as “10.7 cm solar radio” or simply “F10.7”. This service has its roots in World War II.
In 1942, anti-aircraft radars that swept the skies over Britain in search of attackers suddenly became unusable. Huge signals flooded all sorts of potential echoes. The display screens, which were supposed to echo radar, were filled with random dots and spots.
This thing is now called “snow”. The radars were muted. The first fear was that Britain’s air defenses were affected by some secret weapon.
Then one of the engineers turned off the transmitter on one of the radars and swung the antenna around while looking at the display screen. These muffled signals came from the sun. It was a relief to know that no secret weapons were involved, but because every time the sun did whatever it did, the air defenses deteriorated; information about solar attacks was kept secret until after the war.
During the same war, warships at sea used their radars to clear the horizon of possible enemy ships. Operators soon noticed that when the radar antenna was aimed at the rising or setting sun, every echo in that direction was flooded with the same kind of “snow.”
As this phenomenon could be used by potential attackers, it was also kept as quiet as possible.
World War II was a high-tech war. He saw an explosion in the use of radar systems and advanced communication devices, along with efforts to create equipment to silence or defraud enemy radar and communication devices.
When the war ended, there were piles of modern electronics that were no longer needed.
Naturally occurring radio broadcasts from the Milky Way were discovered in the 1930s, which marked the beginning of the embryonic science of radio astronomy. The presence of unwanted military antennas and receiving systems provided a gold mine for the construction of radio telescopes.
During the war, the National Research Council was a center for the development of radar systems. After the war, NRC scientists used parts of these radar systems to make Canada’s first radio telescope. They aimed the instrument at various objects in the sky, but the only thing they could find was the sun, so they decided to measure exactly these solar radio emissions and how they varied.
At the start of the war, Britain shared its military secrets with the United States and Canada. These include a resonant cavity magnetron. This device can generate high transmitter power at centimeter wavelengths.
This was especially necessary for on-board radar systems; short wavelengths mean that smaller antennas can be used. It is difficult to place large antennas in airplanes. The magnetrons operated at a wavelength of about 10.7 cm, so did the radars.
So did the NRC radio telescope. Measurements of solar radio emissions at this wavelength have been shown to be a good indicator of the full range of solar activity,
That is why this service has continued to this day.
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Venus is low at dawn. To his right lie Mars and Jupiter, close together, then Saturn. The moon will reach the first quarter on Tuesday and will be full on June 14.
Ken Tapping is an astronomer at the Dominion Radio Astrophysical Observatory of the National Research Council near Penticton
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