Correlation plots of the Siberian Radioheliograph

The Siberian Solar Radio Telescope [Grechnev et al., 2011] is now being upgraded. The upgrading is aimed at providing the aperture synthesis imaging in the frequency range 4–8 GHz [Lesovoi et al., 2011, 2014] instead of the single-frequency direct imaging due to the Earth rotation. The first phase of the upgrading is a 48-antenna array — Siberian Radioheliograph. One type of radioheliograph data represents correlation plots [badary.iszf.irk.ru/srhCorrPlot.php]. In evaluating the covariation of two-level signals, these plots are sums of complex correlations, obtained for different antenna pairs. Bearing in mind that correlation of signals from an antenna pair is related to a spatial frequency, we can say that each value of the plot is an integral over a spatial spectrum. Limits of the integration are defined by a task. Only high spatial frequencies are integrated to obtain dynamics of compact sources. The whole spectrum is integrated to reach maximum sensitivity. We show that the covariation of two-level values accurate to Van Vleck correction is a correlation coefficient of these values.

Siberian Radioheliograph: first results

Regular observations of active processes in the solar atmosphere have been started using the first stage of the multiwave Siberian Radioheliograph (SRH), a T-shaped 48-antenna array with a 4–8 GHz operating frequency range and a 10 MHz instantaneous receiving band. Antennas are mounted on the central antenna posts of the Siberian Solar Radio Telescope. The maximum baseline is 107.4 m, and the angular resolution is up to 70". We present examples of observations of the solar disk at different frequencies, “negative” bursts, and solar flares. The sensitivity to compact sources reaches 0.01 solar flux units (≈10^{-4} of the total solar flux) with an accumulation time of about 0.3 s. The high sensitivity of SRH enables monitoring of solar activity and allows studying active processes from characteristics of their microwave emission, including faint events, which could not be detected previously.

Siberian Radioheliograph: first results

Regular observations of active processes in the solar atmosphere have been started using the first stage of the multiwave Siberian Radioheliograph (SRH), a T-shaped 48-antenna array with a 4–8 GHz operating frequency range and a 10 MHz instantaneous receiving band. Antennas are set on the central antenna posts of the Siberian Solar Radio Telescope. The maximum baseline is 107.4 m, and the angular resolution is up to 70ʹʹ. We present examples of observations of the solar disk at different frequencies, “negative” bursts, and solar flares. The sensitivity to compact sources reaches 0.01 solar flux units (≈10^{-4} of the total solar flux) with an accumulation time of 0.3 s. The high sensitivity of the SRH enables monitoring of solar activity and allows one to study active processes from characteristics of their microwave emission, including faint events, which could not be detected previously.

Correlation plots of the Siberian Radioheliograph

The Siberian Solar Radio Telescope [Grechnev et al., 2011] is now being upgraded. The upgrading is aimed at providing the aperture synthesis imaging in the frequency range 4–8 GHz [Lesovoi et al., 2011, 2014] instead of the single-frequency direct imaging due to the Earth rotation. The first phase of the upgrading is a 48-antenna array — Siberian Radioheliograph. One type of radioheliograph data represents correlation plots [badary.iszf.irk.ru/srhCorrPlot.php]. In evaluating the covariation of two-level signals, these plots are sums of complex correlations, obtained for different antenna pairs. Bearing in mind that correlation of signals from an antenna pair is related to a spatial frequency, we can say that each value of the plot is an integral over a spatial spectrum. Limits of the integration are defined by a task. Only high spatial frequencies are integrated to obtain dynamics of compact sources. The whole spectrum is integrated to reach maximum sensitivity. We show that the covariation of two-level values accurate to Van Vleck correction is a correlation coefficient of these values.

Sources of type III solar microwave bursts

Microwave fine structures allow us to study plasma evolution in an energy release region. The Siberian Solar Radio Telescope (SSRT) is a unique instrument designed to examine fine structures at 5.7 GHz. A complex analysis of data from RATAN-600, 4–8 GHz spectropolarimeter, and SSRT, simultaneously with EUV data, made it possible to localize sources of III type microwave bursts in August 10, 2011 event within the entire frequency band of burst occurrence, as well as to determine the most probable region of primary energy release. To localize sources of III type bursts from RATAN-600 data, an original method for data processing has been worked out. At 5.7 GHz, the source of bursts was determined along two coordinates, whereas at 4.5, 4.7, 4.9, 5.1, 5.3, 5.5, and 6.0 GHz, their locations were identified along one coordinate. The size of the burst source at 5.1 GHz was found to be maximum as compared to those at other frequencies.

Sources of type III solar microwave bursts

Microwave fine structures allow us to study plasma evolution in an energy release region. The Siberian Solar Radio Telescope (SSRT) is a unique instrument designed to examine fine structures at 5.7 GHz. A complex analysis of data from RATAN-600, 4–8 GHz spectropolarimeter, and SSRT, simultaneously with extreme UV data, made it possible to localize sources of III type microwave drift bursts in August 10, 2011 event within the entire frequency band of burst occurrences, as well as to determine the most probable region of primary energy release. To localize sources of III type bursts from RATAN-600 data, an original method for data processing has been worked out. At 5.7 GHz, the source of bursts was determined along two coordinates whereas at 4.5, 4.7, 4.9, 5.1, 5.3, 5.5 and 6.0 GHz, their locations were identified along one coordinate. The size of the burst source at 5.1 GHz was found to be maximum as compared to source sizes at other frequencies.