Siberian Radioheliograph: first results

Abstract

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.

Coronal Jets as a Cause of Microwave Negative Bursts

“…Besides being absorbed by the material of the erupting prominence, radio emission can also be screened by the material of small-scale plasma eruptions [Lesovoi et al, 2017;Fedotova et al, 2018;Grechnev et al, 2018], which are classified as surges (in Hα) and jets (in extreme ultraviolet and X-ray ranges). Observations of jets in the extreme ultraviolet range have revealed both cold (10 4 -10 5 K) and hot plasma (10 6 K) [Raouafi et al, 2016].…”

Microwave indicator of potential geoeffectiveness and magnetic flux-rope structure of a solar active region

“…One of the objectives of the under-construction Siberian Radioheliograph (SRH) [Lesovoi et al, 2017;Altyntsev et al, 2020] is to assess the ability of solar active regions (ARs) to produce energetic flares and coronal mass ejections (CMEs). The final configuration of SRH will be able to map ARs with an angular resolution from 30" to 7" in a frequency range from 3 to 24 GHz.…”

“…NLSs were occasionally recorded during solar observations by large multipurpose radio telescopes: Westerbork Synthesis Radio Telescope (WSRT), Very Large Array (VLA), RATAN-600, and were also investigated using regular observations made with the Siberian Solar Radio Telescope (SSRT) [Smolkov et al, 1986;Grechnev et al, 2003] and the Nobeyama Radioheliograph (NoRH) [Nakajima et al, 1994]. WSRT observed NLSs at 5 GHz; VLA, at 4.9, 8.4, and 15 GHz; SSRT, at 5.7 GHz; RATAN-600, at several frequencies; NoRH, at 17 GHz and in one case even at 34 GHz.…”

Calibration of Siberian Radioheliograph Images

“…Чувствительность радиогелиографов недостаточна для наблюдений калиброванных звездных источников и требует реализации методов, отличающихся от методов калибровки звездных интерферометров. Нами использовался опыт наблюдений на радиогелиографах, ведущих мониторинг активности Солнца в микроволновом диапазоне: Сибирском солнечном радиотелескопе (ССРТ) [http://ru.iszf.irk.ru; Grechnev et al, 2003;Kochanov et al, 2013] и радиогелиографе Нобеямы (NoRG) [https: //solar.nro.nao.ac.jp/norh/html;.…”