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## Solar Eclipse on June 21, 2020 According to Observations with IAA RAS Radio Telescopes (First Results)

Transactions of IAA RAS, issue 56, 22–31 (2021)

D. V. Ivanov, I. A. Rakhimov, A. A. Dyakov, V. G. Olifirov, D. V. Erofeev, N. A. Topchilo, N. G. Peterova, A. V. Ipatov, T. S. Andreeva, G. N. Il’in, E. Yu. Khvostov. Solar Eclipse on June 21, 2020 According to Observations with IAA RAS Radio Telescopes (First Results) // Transactions of IAA RAS. — 2021. — Issue 56. — P. 22–31. @article{ivanov2021, abstract = {The solar eclipse on June 21, 2020 (phase 0.17–0.24) is the seventh case of observations of solar eclipses using the full-circle full-steering radio telescopes RT-32, RT-13 and RT-2 located at “Zelenchukskaya” observatory in the North Caucasus, observatory “Badary” in Buryatia and Ussurijskaya Astrophysical Observatory (UAO) in the Primorsky Territory, which are under the jurisdiction of the IAA RAS. Observation tasks were determined by astronomical circumstances — the Sun was in the stage of the deepest minimum, which, in contrast to previous cases, highlighted the study of faint details of the Sun's image structure, such as the radio brightness distribution near the limb, coronal holes, radio granulation, which are still insufficiently studied. The observation method is considered to be the best due to the application of a quasi-zero method of signal registration by using radio telescopes with a sufficiently high spatial resolution (2–4)' at high frequincies (several angular minutes), which limits the contribution of the quiet Sun. The theoretical limit of the effective angular resolution of eclipsing observations — (1–3)" at microwaves was first reached using the RT-32. Observations of the solar eclipse on June 21, 2020 at RT-13 and RT-32 were carried out at 1.0 cm, 3.5 cm, 6.2 cm, and 13 cm with circular polarization analysis, at RT-2 at 10.7 cm in intensity. Original records and results of primary processing are presented, as well as preliminary identification of individual details of the structure of microwave radiation sources by comparison with observations of the Sun in other ranges (UV and X-ray). The analysis of observations of the quiet Sun areas showed that the angular sizes of individual radio granulation details do not exceed 10 arcsecond, and there is a high degree of correlation between fluctuations at short (3.5 cm) and long (13 cm) wavelengths. The individual radio granulation radiation is generated rather high in the corona at a distance exceeding 10 thousand km from the photosphere. Processing of observations when aiming at contact regions I and IV allows us to conclude that the brightness of the corona has significantly decreased in comparison with the previously obtained values. However, this concerns the brightness of the active corona — the quiet Sun radio flux observed during the minimum cycle (from the 19th to the 25th) remains unchanged in a wide frequency range (1–9.4 GHz).}, author = {D.~V. Ivanov and I.~A. Rakhimov and A.~A. Dyakov and V.~G. Olifirov and D.~V. Erofeev and N.~A. Topchilo and N.~G. Peterova and A.~V. Ipatov and T.~S. Andreeva and G.~N. Il’in and E.~Yu. Khvostov}, doi = {10.32876/ApplAstron.56.22-31}, issue = {56}, journal = {Transactions of IAA RAS}, keyword = {radio telescope, solar eclipse, eclipse curve, radio image, active region, corona, radio emission}, pages = {22--31}, title = {Solar Eclipse on June 21, 2020 According to Observations with IAA RAS Radio Telescopes (First Results)}, url = {http://iaaras.ru/en/library/paper/2080/}, year = {2021} } TY - JOUR TI - Solar Eclipse on June 21, 2020 According to Observations with IAA RAS Radio Telescopes (First Results) AU - Ivanov, D. V. AU - Rakhimov, I. A. AU - Dyakov, A. A. AU - Olifirov, V. G. AU - Erofeev, D. V. AU - Topchilo, N. A. AU - Peterova, N. G. AU - Ipatov, A. V. AU - Andreeva, T. S. AU - Il’in, G. N. AU - Khvostov, E. Yu. PY - 2021 T2 - Transactions of IAA RAS IS - 56 SP - 22 AB - The solar eclipse on June 21, 2020 (phase 0.17–0.24) is the seventh case of observations of solar eclipses using the full-circle full- steering radio telescopes RT-32, RT-13 and RT-2 located at “Zelenchukskaya” observatory in the North Caucasus, observatory “Badary” in Buryatia and Ussurijskaya Astrophysical Observatory (UAO) in the Primorsky Territory, which are under the jurisdiction of the IAA RAS. Observation tasks were determined by astronomical circumstances — the Sun was in the stage of the deepest minimum, which, in contrast to previous cases, highlighted the study of faint details of the Sun's image structure, such as the radio brightness distribution near the limb, coronal holes, radio granulation, which are still insufficiently studied. The observation method is considered to be the best due to the application of a quasi-zero method of signal registration by using radio telescopes with a sufficiently high spatial resolution (2–4)' at high frequincies (several angular minutes), which limits the contribution of the quiet Sun. The theoretical limit of the effective angular resolution of eclipsing observations — (1–3)" at microwaves was first reached using the RT-32. Observations of the solar eclipse on June 21, 2020 at RT-13 and RT-32 were carried out at 1.0 cm, 3.5 cm, 6.2 cm, and 13 cm with circular polarization analysis, at RT-2 at 10.7 cm in intensity. Original records and results of primary processing are presented, as well as preliminary identification of individual details of the structure of microwave radiation sources by comparison with observations of the Sun in other ranges (UV and X-ray). The analysis of observations of the quiet Sun areas showed that the angular sizes of individual radio granulation details do not exceed 10 arcsecond, and there is a high degree of correlation between fluctuations at short (3.5 cm) and long (13 cm) wavelengths. The individual radio granulation radiation is generated rather high in the corona at a distance exceeding 10 thousand km from the photosphere. Processing of observations when aiming at contact regions I and IV allows us to conclude that the brightness of the corona has significantly decreased in comparison with the previously obtained values. However, this concerns the brightness of the active corona — the quiet Sun radio flux observed during the minimum cycle (from the 19th to the 25th) remains unchanged in a wide frequency range (1–9.4 GHz). DO - 10.32876/ApplAstron.56.22-31 UR - http://iaaras.ru/en/library/paper/2080/ ER -