<Ul> <Li> Nançay Radioheliographe (NRH) is an interferometer composed of 48 antennas observing at meter - decimeter wavelengths . The radioheliographe is installed at the Nançay Radio Observatory, France . </Li> <Li> Owens Valley Solar Array (OVSA) is a radio interferometer operated by the New Jersey Institute of Technology consisting of 7 antennas, observing from 1 to 18 GHz in both left and right circular polarization . OVSA is located in Owens Valley, California . It is now being improved, increasing to 15 the total number of antennas and upgrading its control system . </Li> <Li> Nobeyama Radioheliograph (NoRH) is an interferometer installed at the Nobeyama Radio Observatory, Japan, formed by 84 small (80 cm) antennas, with receivers at 17 GHz (left and right polarization) and 34 GHz operating simultaneously . It continuously observes the Sun, producing daily snapshots . </Li> <Li> Siberian Solar Radio Telescope (SSRT) is a special - purpose solar radio telescope designed for studying solar activity in the microwave range (5.7 GHz) where the processes occurring in the solar corona are accessible to observation over the entire solar disk . It is a crossed interferometer, consisting of two arrays of 128x128 parabolic antennas 2.5 meters in diameter each, spaced equidistantly at 4.9 meters and oriented in the E-W and N-S directions . It is located in a wooded valley separating two mountain ridges of the Eastern Sayan Mountains and Khamar - Daban, 220 km from Irkutsk, Russia . </Li> <Li> Nobeyama Radio Polarimeters are a set of radio telescopes installed at the Nobeyama Radio Observatory that continuously observes the full Sun (no images) at the frequencies of 1, 2, 3.75, 9.4, 17, 35, and 80 GHz, at left and right circular polarization . </Li> <Li> Solar Submillimeter Telescope is a single dish telescope, that observes continuously the Sun at 212 and 405 GHz . It is installed at Complejo Astronomico El Leoncito in Argentina . It has a focal array composed by 4 beams at 212 GHz and 2 at 405 GHz, therefore it can instantaneously locate the position of the emitting source SST is the only solar submillimeter telescope currently in operation . </Li> <Li> Polarization Emission of Millimeter Activity at the Sun (POEMAS) is a system of two circular polarization solar radio telescopes, for observations of the Sun at 45 and 90 GHz . The novel characteristic of these instruments is the capability to measure circular right - and left - hand polarizations at these high frequencies . The system is installed at Complejo Astronomico El Leoncito in Argentina . It started operations in November 2011 . In November 2013 it went offline for repairs . It is expected to return to observing in January 2015 . </Li> <Li> Bleien Radio Observatory is a set of radio telescopes operating near Gränichen (Switzerland). They continuously observe the solar flare radio emission from 10 MHz (ionospheric limit) to 5 GHz . The broadband spectrometers are known as Phoenix and CALLISTO . </Li> </Ul> <Li> Nançay Radioheliographe (NRH) is an interferometer composed of 48 antennas observing at meter - decimeter wavelengths . The radioheliographe is installed at the Nançay Radio Observatory, France . </Li> <Li> Owens Valley Solar Array (OVSA) is a radio interferometer operated by the New Jersey Institute of Technology consisting of 7 antennas, observing from 1 to 18 GHz in both left and right circular polarization . OVSA is located in Owens Valley, California . It is now being improved, increasing to 15 the total number of antennas and upgrading its control system . </Li> <Li> Nobeyama Radioheliograph (NoRH) is an interferometer installed at the Nobeyama Radio Observatory, Japan, formed by 84 small (80 cm) antennas, with receivers at 17 GHz (left and right polarization) and 34 GHz operating simultaneously . It continuously observes the Sun, producing daily snapshots . </Li>

When is a solar flare observed on earth