project. The RATAN-600 has not suffered from the persistent technical problems of the neighbouring BTA-6, and has generally been in high demand since it began operation in mid-1974. SETI candidate signal On 15 May 2015, at 18:01:15.65 sidereal time, RATAN-600 detected a strong (0.75 Jansky) signal from the direction of HD164595. More specifically, the signal intensity rose and fell as the telescope panned past in a way that closely matched what would be expected for a distant source. Since the short wavelength (2.7 cm, or 11 GHz, in the X band) is unusual for a natural source of that power, after the researchers announced the signal in late August 2016 (in the form of a request for follow-up observations) there was a flurry of excitement that it might be a SETI candidate. Of course, the same artificial appearance also makes a terrestrial source likely. Because the signal is in a frequency band allocated to military use, it might have originated from a secret reconnaissance satellite. After further analysis, and a failure of other observatories to corroborate the signal, the Special Astrophysical Observatory concluded that it was of probably terrestrial origin. Later research suggests that it might have been a faulty satellite in a slow spin, as the frequency matches one used for inter-satellite beacons, but was more likely to be the downlink from an intact but classified satellite. Gallery See also Radio astronomy Five-hundred-meter Aperture Spherical Telescope world's second largest-diameter individual radio telescope References Radio telescopes Buildings and structures in Karachay-Cherkessia Soviet inventions Records (superlatives)