The Multifrequency Siberian Radioheliograph

The ten-antenna prototype of the multifrequency Siberian radioheliograph is described. The prototype consists of four parts: antennas with broadband front-ends, analog back-ends, digital receivers and a correlator. The prototype antennas are mounted on the outermost stations of the Siberian Solar Radio Telescope (SSRT) array. A signal from each antenna is transmitted to a workroom by an analog fiber optical link, laid in an underground tunnel. After mixing, all signals are digitized and processed by digital receivers before the data are transmitted to the correlator. The digital receivers and the correlator are accessible by the Local Area Network (LAN). The frequency range of the prototype is from 4 to 8 GHz. Currently the frequency switching observing mode is used. The prototype data include both circular polarizations at a number of frequencies given by a list. This prototype is the first stage of the multifrequency Siberian radioheliograph development. It is assumed that the radioheliograph will consist of 96 antennas and will occupy stations of the West–East–South subarray of the SSRT. The radioheliograph will be fully constructed in the autumn of 2012. We plan to reach the brightness temperature sensitivity of about 100 K for the snapshot image, a spatial resolution up to 13 arcseconds at 8 GHz and a polarization measurement accuracy about a few percent. First results with the ten-antenna prototype are presented of observations of solar microwave bursts. The prototype’s abilities to estimate source size and locations at different frequencies are discussed.