A detailed study is made of the birth and development of more than 20 active regions based on rad... more A detailed study is made of the birth and development of more than 20 active regions based on radio maps obtained by the Siberian Solar Radio Telescope at 5.7 GHz. We found 23 events with fast increasing of total flux from one average level to the other. In some ...
The results of a study of the coronal mass ejection (CME) of April 27, 2003, which was intrinsica... more The results of a study of the coronal mass ejection (CME) of April 27, 2003, which was intrinsically associated with the active region NOAA 10338, are reported. Particular attention is paid to the initial stage of the event, which was accompanied by X-ray bursts of class C9.3 and C6.7, with the aim of determining the origin of CMEs. The energy source of the ejection was in the active region NOAA 10338. This region had a complicated and dynamic magnetic-field topology, and produced a series of CMEtype events. The basis for the study was observations at wavelengths of 1.92-17 cm with high spatial resolution, 17-20 , obtained on the Siberian Solar Radio Telescope (SSRT) and RATAN-600, together with simultaneous data from the Nobeyama Radio Heliograph (NoRH, wavelength 1.76 cm) and 195Å ultraviolet data from the TRACE spacecraft. The development of the event was followed over three hours, first through observations against the disk at heights of 10,000-100,000 km from the photosphere, then in the post-limb stage to distances of the order of 10 6 km from the solar center, i.e., in the zone inaccessible to the LASCO coronographs. According to the radio observations, ∼10 min before the beginning of the event, the radio structure of the active region NOAA 10338 had an S-shaped (sigmoid) configuration. A rising, gradually expanding dark loop originated at the points where this structure was observed; according to the TRACE data, this loop initiated the event. Subsequently, the structure of the radio image drastically changed, suggesting that coronal plasma was heated and cooled at different sites of the emission region (or was shielded by the cooler material of the ejection). Profiles of the burst that accompanied the ejection are presented for four points in the region. The post-limb part of the event first had a compact (∼50) structure receding from the Sun and visible to distances ∼10 6 km. An asymmetric loop was then formed, with its material falling back onto the Sun at the end of the event. The brightness temperature of the loop was ∼15 × 10 3 K, and its emission was weakly polarized (P ≈16%). The mean speed of the material was 160 km/s. It is concluded that the observations of the event of April 27, 2003 are most consistent with the model of Amari et al., in which the formation of an eruptive twisted magnetic rope, taken to be responsible for CME-type events, is explained by the emergence of new magnetic flux within an old field of opposite polarity.
On 23 July 2016 after 05:00 UTC, the first 48-antenna stage of the Siberian Radioheliograph detec... more On 23 July 2016 after 05:00 UTC, the first 48-antenna stage of the Siberian Radioheliograph detected two flares of M7.6 and M5.5 GOES importance that occurred within half an hour in the same active region. Their multi-instrument analysis reveals the following. The microwave spectra were
We describe methods for monitoring eruption activity with the first phase of the multiwave Siberi... more We describe methods for monitoring eruption activity with the first phase of the multiwave Siberian Radioheliograph (SRH-48). We give examples of the recorded eruptive events: 1) rise of a prominence above the limb observed in the radio map sequence of April 24, 2017; 2) a jet recorded on August 2, 2017, whose cold matter screened a compact microwave source for several tens of minutes. The shading due to the jet appearance was observed on SRH-48 correlation curves as the so-called "negative" burst. Using the "negative" burst on the correlation curves of February 9, 2017 as an example, we show that the intervals with depression of the microwave emission of local sources are not always caused by shading of their emission. In this event, the radio brightness decreased within ten hour period of the increased quasi-stationary emission during the development of AR 12635 magnetic structure. Similar behavior was observed in EUV, SXR, and radio emission at 17 GHz.
We demonstrate observations of such well-known relatively quiet solar features as filaments & pro... more We demonstrate observations of such well-known relatively quiet solar features as filaments & prominences, coronal holes, bright points, and arcades with two radioheliographs, SSRT at 5.7 GHz and NoRH at 17 GHz. Simultaneous microwave observations with the two radioheliographs are promising and fruitful due to overlapping observational daytimes and three times different frequencies. Last circumstance determines significantly different coronal contribution at those frequencies, which governs dissimilar appearance of coronal features in images produced by the NoRH and SSRT. The emphasis is made on SSRT observations, which are not yet well known. We overview some results obtained with the two radioheliographs and discuss new opportunities of radioheliographic observations. Microwave observations are also compared with magnetograms. Only observations at several radio frequencies assure correct estimates of the magnetic field.
Аннотация. В статье обсуждаются характеристики, фундаментальные и прикладные задачи создаваемого ... more Аннотация. В статье обсуждаются характеристики, фундаментальные и прикладные задачи создаваемого на площадке Радиоастрофизической обсерватории ИСЗФ СО РАН Сибирского радиогелиографа и комплекса спектрополяриметров интегрального потока излучения Солнца. Многоволновое картографирование Солнца в микроволновом диапазоне является мощным и относительно недорогим по сравнению с космическими технологиями средством слежения за процессами солнечной активности и средством диагностики параметров плазмы. Всепогод-Abstract. The article discusses characteristics, fundamental and applied tasks of the Siberian Radioheliograph that is developed at the ISTP SB RAS Radio Astrophysical Observatory and spectropolarimetric complex that measures the total flux of solar radio emission. The multi-wave mapping of the Sun in the microwave range is a powerful and relatively inexpensive, in comparison with space technologies, means of observing solar activity processes and diagnosing plasma parameters. All-weather monitoring of electromagnetic solar emission (in the range from meter to millimeter waves,
Journal of Atmospheric and Solar-Terrestrial Physics, 2018
The first 48-antenna stage of the Siberian Radioheliograph (SRH) started single-frequency test ob... more The first 48-antenna stage of the Siberian Radioheliograph (SRH) started single-frequency test observations early in 2016, and since August 2016 it routinely observes the Sun at several frequencies in the 4-8 GHz range with an angular resolution of 1-2 arc minutes and an imaging interval of about 12 seconds. With limited opportunities of the incomplete antenna configuration, a high sensitivity of about 100 Jy allows the SRH to contribute to the studies of eruptive phenomena along three lines. First, some eruptions are directly visible in SRH images. Second, some small eruptions are detectable even without a detailed imaging information from microwave depressions caused by screening the background emission by cool erupted plasma. Third, SRH observations reveal new aspects of some events to be studied with different instruments. We focus on an eruptive C2.2 flare on 16 March 2016 around 06:40, one of the first flares observed by the SRH. Proceeding from SRH observations, we analyze this event using extreme-ultraviolet, hard X-ray, white-light, and metric radio data. An eruptive prominence expanded, brightened, and twisted, which indicates a time-extended process of the flux-rope formation together with the development of a large coronal mass ejection (CME). The observations rule out a passive role of the prominence in the CME formation. The abrupt prominence eruption impulsively excited a blast-wave-like shock, which appeared during the microwave burst and was manifested in an "EUV wave" and Type II radio burst. The shock wave decayed and did not transform into a bow shock because of the low speed of the CME. Nevertheless, this event produced a clear proton enhancement near Earth. Comparison with our previous studies of several events confirms that the impulsive-piston shock-excitation scenario is typical of various events.
We analyzed spatial and spectral characteristics of quasi-periodic pulses (QPP) for the 18 August... more We analyzed spatial and spectral characteristics of quasi-periodic pulses (QPP) for the 18 August 2012 limb flare, using new data from a complex of spectral and imaging instruments developed by the Siberian Solar Radio Telescope team and the Wind/Konus gamma-ray spectrometer. A sequence of broadband pulses with periods of approximately ten seconds were observed in Xrays at energies between 25 keV and 300 keV, and in microwaves at frequencies from a few GHz up to 34 GHz during an interval of one minute. The QPP Xray source was located slightly above the limb where the south legs of large and small EUV loop systems were close to each other. Before the QPPs the soft X-ray emission and the Ramaty High Energy Solar Spectroscopic Imager signal from the energy channels below 25 keV were gradually arising for several minutes at the same location. It was found that each X-ray pulse showed the soft-hard-soft behavior. The 17 and 34 GHz microwave source were at footpoints of the small loop system and the source emitting in the 4.2-7.4 GHz band in the large one. The QPPs were probably generated by modulation of acceleration processes in the energy release site. Analyzing radio spectra we determined the plasma parameters in the radio sources. The microwave pulses could be explained by relatively weak variations of the spectrum hardness of emitting electrons.
Proceedings of the International Astronomical Union, 2004
Using multi-spectral data, we estimate plasma parameters in the post-eruptive arcade observed on ... more Using multi-spectral data, we estimate plasma parameters in the post-eruptive arcade observed on October 22, 2001 at 100 Mm above the limb: the temperature is 6 MK and the plasma density is (5 − 9) • 10 9 cm −3. We state a problem of the long-term equilibrium of the hot top of the arcade high in the corona: either the magnetic field surrounding the arcade well exceeds that one extrapolated in the potential approximation, or β > 1 both inside and outside the arcade. A downflow observed in soft X-rays can contribute to the equilibrium.
During a measurement campaign in winter 2006 spectrum measurements were done at difierent loca- t... more During a measurement campaign in winter 2006 spectrum measurements were done at difierent loca- tions in India and Sibiria. This report describes the results of Badary solar radio telescope (SSRT) site in Sibiria (Russian Federation). Measurements were done with a broadband logarithmic periodic antenna of the site con- nected to a Callisto spectrometer designed and built by ETH Zurich (Benz, 2004). This measurement campaign shall be the technical basis to decide how to continue concerning spectroscopic measurements below 1GHz with existing antennas and/or new ones. The results are presented, compared with Switzerland and discussed in form of digitally zoomed spectrums in the most interesting radio astronomy frequency ranges. In terms of electromag- netic interference Badary is much better than Switzerland and thus ideal for low frequency solar radio astronomy observations (spectroscopy).
Proceedings of The Multifaceted Universe: Theory and Observations - 2022 — PoS(MUTO2022)
The study of the solar corona plays a key role in understanding solar activity. Microwave imaging... more The study of the solar corona plays a key role in understanding solar activity. Microwave imaging spectroscopy-measuring microwave spectra at every point on the solar disk (or image)-is the most promising method for studying the lower corona and the chromosphere-corona transition region. Solar microwave emission originates in the low corona and in the upper chromosphere and is produced both by thermal and non-thermal electrons. The main types of emission are bremsstrahlung, gyroresonance and gyrosynchrotron emission. The quiet Sun emission is dominated by the bremsstrahlung while the active region emission is due to the gyroresonance mechanism. The gyrosynchrotron emission is generated by non-thermal electrons during solar flares. Microwave emission spectra allow us to estimate the temperature and density of the plasma in active regions. Microwave spectroscopy of the solar corona is perhaps the only method for measuring the coronal magnetic field both for the quiet Sun and for transient events. The Siberian Radioheliograph (SRH), a new generation solar radio telescope, is described, and the first observations of solar activity in the broadband frequency range 3-24 GHz are presented. The estimation of the magnetic field scale length is presented. The scale length was estimated by using the SRH data-spectra of an active region emission in the frequency range 3-12 GHz.
We discuss the method for automatic calibration of solar radio images derived from the first stag... more We discuss the method for automatic calibration of solar radio images derived from the first stage of the multiwave Siberian Radioheliograph (SRH-48). SRH is a 48-element T-shaped radiointerferometer in the 4–8 GHz frequency range. Since the end of 2017, the number of frequencies has been increased to 32. The method is implemented in Python programming language. We give examples of calibration for SRH instrument values in brightness temperature of the quiet and active Sun at several frequencies for four eruptive events: June 19, 2017, July 25, 2016, April 24, 2017, and April 19, 2017. In conclusion, we present spectra for three events, as well as brightness temperature estimates by flux, angular size of filaments, and emission measure.
Microwave fine structures allow us to study plasma evolution in an energy release region. The Sib... more 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.
Symposium - International Astronomical Union, 2001
On 23 September 1998 there was a 3B/M7.1 flare event starting at 06:40 UT with more than 100 minu... more On 23 September 1998 there was a 3B/M7.1 flare event starting at 06:40 UT with more than 100 minute duration radio bursts of 1134 sfu peak flux at 2840 MHz and accompanying a CME. In this paper, the event is analyzed with the data observed by Beijing Astronomical Observatory (BAO), OSRA-Tremsdorf (AIP) and SSRT-ISTP. In particular, we compare the fine structures (FS) during the triggering phase revealed in different regimes and discuss their implications.
Proceedings of the International Astronomical Union, 2004
The observations of the bursts with fine structures are one of the best remote sensing probe of t... more The observations of the bursts with fine structures are one of the best remote sensing probe of the primary energy release sites in solar flares. The Siberian Solar Radiotelescope (SSRT) gives us the unique possibility of direct measurements of their positions with temporal resolution up to 14 ms and spatial resolution of a few arcsec. National Astronomical Observatories of China (NAOC) spectropolarimeters (5.2-7.7 GHz) provide us with the simultaneous spectral data around the SSRT receiving frequency (5.7 GHz). An analysis is made of the subsecond pulses observations: short wide range pulses, U-type microwave bursts, the bursts with zebra pattern.
A detailed study is made of the birth and development of more than 20 active regions based on rad... more A detailed study is made of the birth and development of more than 20 active regions based on radio maps obtained by the Siberian Solar Radio Telescope at 5.7 GHz. We found 23 events with fast increasing of total flux from one average level to the other. In some ...
The results of a study of the coronal mass ejection (CME) of April 27, 2003, which was intrinsica... more The results of a study of the coronal mass ejection (CME) of April 27, 2003, which was intrinsically associated with the active region NOAA 10338, are reported. Particular attention is paid to the initial stage of the event, which was accompanied by X-ray bursts of class C9.3 and C6.7, with the aim of determining the origin of CMEs. The energy source of the ejection was in the active region NOAA 10338. This region had a complicated and dynamic magnetic-field topology, and produced a series of CMEtype events. The basis for the study was observations at wavelengths of 1.92-17 cm with high spatial resolution, 17-20 , obtained on the Siberian Solar Radio Telescope (SSRT) and RATAN-600, together with simultaneous data from the Nobeyama Radio Heliograph (NoRH, wavelength 1.76 cm) and 195Å ultraviolet data from the TRACE spacecraft. The development of the event was followed over three hours, first through observations against the disk at heights of 10,000-100,000 km from the photosphere, then in the post-limb stage to distances of the order of 10 6 km from the solar center, i.e., in the zone inaccessible to the LASCO coronographs. According to the radio observations, ∼10 min before the beginning of the event, the radio structure of the active region NOAA 10338 had an S-shaped (sigmoid) configuration. A rising, gradually expanding dark loop originated at the points where this structure was observed; according to the TRACE data, this loop initiated the event. Subsequently, the structure of the radio image drastically changed, suggesting that coronal plasma was heated and cooled at different sites of the emission region (or was shielded by the cooler material of the ejection). Profiles of the burst that accompanied the ejection are presented for four points in the region. The post-limb part of the event first had a compact (∼50) structure receding from the Sun and visible to distances ∼10 6 km. An asymmetric loop was then formed, with its material falling back onto the Sun at the end of the event. The brightness temperature of the loop was ∼15 × 10 3 K, and its emission was weakly polarized (P ≈16%). The mean speed of the material was 160 km/s. It is concluded that the observations of the event of April 27, 2003 are most consistent with the model of Amari et al., in which the formation of an eruptive twisted magnetic rope, taken to be responsible for CME-type events, is explained by the emergence of new magnetic flux within an old field of opposite polarity.
On 23 July 2016 after 05:00 UTC, the first 48-antenna stage of the Siberian Radioheliograph detec... more On 23 July 2016 after 05:00 UTC, the first 48-antenna stage of the Siberian Radioheliograph detected two flares of M7.6 and M5.5 GOES importance that occurred within half an hour in the same active region. Their multi-instrument analysis reveals the following. The microwave spectra were
We describe methods for monitoring eruption activity with the first phase of the multiwave Siberi... more We describe methods for monitoring eruption activity with the first phase of the multiwave Siberian Radioheliograph (SRH-48). We give examples of the recorded eruptive events: 1) rise of a prominence above the limb observed in the radio map sequence of April 24, 2017; 2) a jet recorded on August 2, 2017, whose cold matter screened a compact microwave source for several tens of minutes. The shading due to the jet appearance was observed on SRH-48 correlation curves as the so-called "negative" burst. Using the "negative" burst on the correlation curves of February 9, 2017 as an example, we show that the intervals with depression of the microwave emission of local sources are not always caused by shading of their emission. In this event, the radio brightness decreased within ten hour period of the increased quasi-stationary emission during the development of AR 12635 magnetic structure. Similar behavior was observed in EUV, SXR, and radio emission at 17 GHz.
We demonstrate observations of such well-known relatively quiet solar features as filaments & pro... more We demonstrate observations of such well-known relatively quiet solar features as filaments & prominences, coronal holes, bright points, and arcades with two radioheliographs, SSRT at 5.7 GHz and NoRH at 17 GHz. Simultaneous microwave observations with the two radioheliographs are promising and fruitful due to overlapping observational daytimes and three times different frequencies. Last circumstance determines significantly different coronal contribution at those frequencies, which governs dissimilar appearance of coronal features in images produced by the NoRH and SSRT. The emphasis is made on SSRT observations, which are not yet well known. We overview some results obtained with the two radioheliographs and discuss new opportunities of radioheliographic observations. Microwave observations are also compared with magnetograms. Only observations at several radio frequencies assure correct estimates of the magnetic field.
Аннотация. В статье обсуждаются характеристики, фундаментальные и прикладные задачи создаваемого ... more Аннотация. В статье обсуждаются характеристики, фундаментальные и прикладные задачи создаваемого на площадке Радиоастрофизической обсерватории ИСЗФ СО РАН Сибирского радиогелиографа и комплекса спектрополяриметров интегрального потока излучения Солнца. Многоволновое картографирование Солнца в микроволновом диапазоне является мощным и относительно недорогим по сравнению с космическими технологиями средством слежения за процессами солнечной активности и средством диагностики параметров плазмы. Всепогод-Abstract. The article discusses characteristics, fundamental and applied tasks of the Siberian Radioheliograph that is developed at the ISTP SB RAS Radio Astrophysical Observatory and spectropolarimetric complex that measures the total flux of solar radio emission. The multi-wave mapping of the Sun in the microwave range is a powerful and relatively inexpensive, in comparison with space technologies, means of observing solar activity processes and diagnosing plasma parameters. All-weather monitoring of electromagnetic solar emission (in the range from meter to millimeter waves,
Journal of Atmospheric and Solar-Terrestrial Physics, 2018
The first 48-antenna stage of the Siberian Radioheliograph (SRH) started single-frequency test ob... more The first 48-antenna stage of the Siberian Radioheliograph (SRH) started single-frequency test observations early in 2016, and since August 2016 it routinely observes the Sun at several frequencies in the 4-8 GHz range with an angular resolution of 1-2 arc minutes and an imaging interval of about 12 seconds. With limited opportunities of the incomplete antenna configuration, a high sensitivity of about 100 Jy allows the SRH to contribute to the studies of eruptive phenomena along three lines. First, some eruptions are directly visible in SRH images. Second, some small eruptions are detectable even without a detailed imaging information from microwave depressions caused by screening the background emission by cool erupted plasma. Third, SRH observations reveal new aspects of some events to be studied with different instruments. We focus on an eruptive C2.2 flare on 16 March 2016 around 06:40, one of the first flares observed by the SRH. Proceeding from SRH observations, we analyze this event using extreme-ultraviolet, hard X-ray, white-light, and metric radio data. An eruptive prominence expanded, brightened, and twisted, which indicates a time-extended process of the flux-rope formation together with the development of a large coronal mass ejection (CME). The observations rule out a passive role of the prominence in the CME formation. The abrupt prominence eruption impulsively excited a blast-wave-like shock, which appeared during the microwave burst and was manifested in an "EUV wave" and Type II radio burst. The shock wave decayed and did not transform into a bow shock because of the low speed of the CME. Nevertheless, this event produced a clear proton enhancement near Earth. Comparison with our previous studies of several events confirms that the impulsive-piston shock-excitation scenario is typical of various events.
We analyzed spatial and spectral characteristics of quasi-periodic pulses (QPP) for the 18 August... more We analyzed spatial and spectral characteristics of quasi-periodic pulses (QPP) for the 18 August 2012 limb flare, using new data from a complex of spectral and imaging instruments developed by the Siberian Solar Radio Telescope team and the Wind/Konus gamma-ray spectrometer. A sequence of broadband pulses with periods of approximately ten seconds were observed in Xrays at energies between 25 keV and 300 keV, and in microwaves at frequencies from a few GHz up to 34 GHz during an interval of one minute. The QPP Xray source was located slightly above the limb where the south legs of large and small EUV loop systems were close to each other. Before the QPPs the soft X-ray emission and the Ramaty High Energy Solar Spectroscopic Imager signal from the energy channels below 25 keV were gradually arising for several minutes at the same location. It was found that each X-ray pulse showed the soft-hard-soft behavior. The 17 and 34 GHz microwave source were at footpoints of the small loop system and the source emitting in the 4.2-7.4 GHz band in the large one. The QPPs were probably generated by modulation of acceleration processes in the energy release site. Analyzing radio spectra we determined the plasma parameters in the radio sources. The microwave pulses could be explained by relatively weak variations of the spectrum hardness of emitting electrons.
Proceedings of the International Astronomical Union, 2004
Using multi-spectral data, we estimate plasma parameters in the post-eruptive arcade observed on ... more Using multi-spectral data, we estimate plasma parameters in the post-eruptive arcade observed on October 22, 2001 at 100 Mm above the limb: the temperature is 6 MK and the plasma density is (5 − 9) • 10 9 cm −3. We state a problem of the long-term equilibrium of the hot top of the arcade high in the corona: either the magnetic field surrounding the arcade well exceeds that one extrapolated in the potential approximation, or β > 1 both inside and outside the arcade. A downflow observed in soft X-rays can contribute to the equilibrium.
During a measurement campaign in winter 2006 spectrum measurements were done at difierent loca- t... more During a measurement campaign in winter 2006 spectrum measurements were done at difierent loca- tions in India and Sibiria. This report describes the results of Badary solar radio telescope (SSRT) site in Sibiria (Russian Federation). Measurements were done with a broadband logarithmic periodic antenna of the site con- nected to a Callisto spectrometer designed and built by ETH Zurich (Benz, 2004). This measurement campaign shall be the technical basis to decide how to continue concerning spectroscopic measurements below 1GHz with existing antennas and/or new ones. The results are presented, compared with Switzerland and discussed in form of digitally zoomed spectrums in the most interesting radio astronomy frequency ranges. In terms of electromag- netic interference Badary is much better than Switzerland and thus ideal for low frequency solar radio astronomy observations (spectroscopy).
Proceedings of The Multifaceted Universe: Theory and Observations - 2022 — PoS(MUTO2022)
The study of the solar corona plays a key role in understanding solar activity. Microwave imaging... more The study of the solar corona plays a key role in understanding solar activity. Microwave imaging spectroscopy-measuring microwave spectra at every point on the solar disk (or image)-is the most promising method for studying the lower corona and the chromosphere-corona transition region. Solar microwave emission originates in the low corona and in the upper chromosphere and is produced both by thermal and non-thermal electrons. The main types of emission are bremsstrahlung, gyroresonance and gyrosynchrotron emission. The quiet Sun emission is dominated by the bremsstrahlung while the active region emission is due to the gyroresonance mechanism. The gyrosynchrotron emission is generated by non-thermal electrons during solar flares. Microwave emission spectra allow us to estimate the temperature and density of the plasma in active regions. Microwave spectroscopy of the solar corona is perhaps the only method for measuring the coronal magnetic field both for the quiet Sun and for transient events. The Siberian Radioheliograph (SRH), a new generation solar radio telescope, is described, and the first observations of solar activity in the broadband frequency range 3-24 GHz are presented. The estimation of the magnetic field scale length is presented. The scale length was estimated by using the SRH data-spectra of an active region emission in the frequency range 3-12 GHz.
We discuss the method for automatic calibration of solar radio images derived from the first stag... more We discuss the method for automatic calibration of solar radio images derived from the first stage of the multiwave Siberian Radioheliograph (SRH-48). SRH is a 48-element T-shaped radiointerferometer in the 4–8 GHz frequency range. Since the end of 2017, the number of frequencies has been increased to 32. The method is implemented in Python programming language. We give examples of calibration for SRH instrument values in brightness temperature of the quiet and active Sun at several frequencies for four eruptive events: June 19, 2017, July 25, 2016, April 24, 2017, and April 19, 2017. In conclusion, we present spectra for three events, as well as brightness temperature estimates by flux, angular size of filaments, and emission measure.
Microwave fine structures allow us to study plasma evolution in an energy release region. The Sib... more 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.
Symposium - International Astronomical Union, 2001
On 23 September 1998 there was a 3B/M7.1 flare event starting at 06:40 UT with more than 100 minu... more On 23 September 1998 there was a 3B/M7.1 flare event starting at 06:40 UT with more than 100 minute duration radio bursts of 1134 sfu peak flux at 2840 MHz and accompanying a CME. In this paper, the event is analyzed with the data observed by Beijing Astronomical Observatory (BAO), OSRA-Tremsdorf (AIP) and SSRT-ISTP. In particular, we compare the fine structures (FS) during the triggering phase revealed in different regimes and discuss their implications.
Proceedings of the International Astronomical Union, 2004
The observations of the bursts with fine structures are one of the best remote sensing probe of t... more The observations of the bursts with fine structures are one of the best remote sensing probe of the primary energy release sites in solar flares. The Siberian Solar Radiotelescope (SSRT) gives us the unique possibility of direct measurements of their positions with temporal resolution up to 14 ms and spatial resolution of a few arcsec. National Astronomical Observatories of China (NAOC) spectropolarimeters (5.2-7.7 GHz) provide us with the simultaneous spectral data around the SSRT receiving frequency (5.7 GHz). An analysis is made of the subsecond pulses observations: short wide range pulses, U-type microwave bursts, the bursts with zebra pattern.
Uploads
Papers by Sergey Lesovoi