RUSENG

March, 27, 2019, 8:20 UTC

Due to malfunctioning of sensor on GOES-15, information on flares has been switched to GOES-14 satellite.

Satellite GOES (NASA). Artwork model of the satellite.

The sensor recording x-ray radiation from the Sun is located on the GOES-15 satellite and has been the main source of information about solar flares in recent years is now showing the instability in a low radiation flux. This conclusion can be drawn from the analysis of the radiation profiles coming from the device. For this reason, from March 26, the LPI space weather centre was temporarily transferred from the information source coming from the GOES-14. It will be transferred back after stabilization of the situation and the operational restoration of the sensor.

Group of satellites GOES, built and maintained by NASA, is one of the oldest groups of operating satellites for scientific purposes. The first space satellite GOES-1, was launched into orbit back in 1975, and since then by replacing each other 16 satellites were launched into space, the last one GOES-17 or GOES-S was turned on about a month ago on February 2019. A special feature of the group is the interchangeability of satellites which is provided by at least two or three satellites are simultaneously placed in Space where is each one can be turned on instead of the other. In particular, at the moment these are the satellites GOES-14 (launched in 2009), GOES-15 (launched in 2010; works since 2011), GOES-16 (launched in 2016; works since 2017) and the already mentioned GOES-17. All the satellites are located in a geostationary orbit from where they have a capacity to transmit data to Earth in real-time.

For Physics of the Sun complex of the solar instruments on GOES which observes a solar activity round-the-clock with the exception of the short seasonal breaks in early spring and autumn, is of the greatest interest. The breaks are associated with the eclipse of the Sun by the Earth and last about an hour every day. Particularly, they can be seen on current charts at about the period of time between 11 and 12 o’clock MSK. The Information on solar flares GOES obtains by measuring the flux of the solar radiation in a wavelength ranging from the 10 to 80 nm which corresponds to soft x-ray radiation. Usually, in this range, Sun forms fairly weak flux which is, however, increases significantly (hundreds and thousands of times) during the flares. In case when within the Earth's orbit this flux rises up to one-millionth of a watt per square meter, then it is considered as a flare of class C has occurred, in case when it increases by another 10 times, then it considered as a flare of M class, and if higher – class X. Record's in history are the flares of level X10 - X20, each of which is equal in energy to thousands of faint flares of class C.

Currently, the sensor on the GOES-15 is showing the instability with a decrease in solar activity to about 1/100 of the level of C-class flare. This is a very low flux, which is hardly never reached on the Sun, except the situation of a very deep minimum. Nevertheless, this is the exact situation which is developing in recent months on the Sun that has, as well, made this problem noticeable. For this reason, soon the information on solar flares will be obtained from the data generated by the GOES-14 satellite which is still functioning. Information on the solar activity charts obtained from more modern satellites, such as GOES-R and GOES-S, is currently not available for the general public.

The question of returning to data from the GOES-15 apparatus will be decided depending on the level of solar activity. As soon as the Sun's activity will systematically begin to exceed the level, which is below is regarded as the instability, the information will again be switched back to this device, or to GOES-R or S. Nevertheless, the current trend of solar activity does not promise this kind of situation in the coming weeks, and, possibly in the months. The transition should not affect the accuracy of recordings of the solar flares.

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