High Dynamic Range Observations of Solar Coronal Transients at Low Radio Frequencies With a Spectro-Correlator

Hariharan, K.; Ramesh, R.; Kathiravan, C.; Abhilash, H. N.; Rajalingam, M.

doi:10.3847/0067-0049/222/2/21

Cited by 19 publications

(11 citation statements)

References 65 publications

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“…So, even when the Sun is at −23° decl., its elevation for GRAPH would be high (≈53°). For radio spectral data, we used observations with the Gauribidanur LOw‐frequency Solar Spectrograph (GLOSS; Ebenezer et al, 2001, 2007; Hariharan et al, 2016; Kishore et al, 2014), Gauribidanur RAdio Spectro‐Polarimeter (GRASP; Hariharan et al, 2015; Kishore et al, 2015; Sasikumar Raja et al, 2013), and e‐CALLISTO (Benz et al, 2009; Monstein et al, 2007). We also used data obtained with the Gauribidanur Radio Interferometric Polarimeter (GRIP; Ramesh et al, 2008).…”

Section: Observationsmentioning

confidence: 99%

Low‐Frequency Radio Observations of the “Quiet” Corona During the Descending Phase of Sunspot Cycle 24

Ramesh

Kumari

Kathiravan

et al. 2020

Geophysical Research Letters

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We carried out a statistical study of the "quiet" solar corona during the descending phase of the Sunspot Cycle 24 (i.e., January 2015 to May 2019) using data obtained with the Gauribidanur RAdioheliograPH (GRAPH) at 53 and 80 MHz simultaneously. Our results show that the equatorial (east-west) diameters of the solar corona at the above two frequencies shrunk steadily. The decrease was found to be due to a gradual reduction in the coronal electron density (N e). Independent estimates of N e in the equatorial region of the "background" corona using white-light coronagraph observations indicate a decline consistent with our findings.

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Section: Observationsmentioning

confidence: 99%

Low‐Frequency Radio Observations of the “Quiet” Corona During the Descending Phase of Sunspot Cycle 24

Ramesh

Kumari

Kathiravan

et al. 2020

Geophysical Research Letters

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“…Space based observations at 14 MHz are carried out using WAVES-WIND (Bougeret et al, 1995), and WAVES-STEREO (Kaiser, 2005;Rucker et al, 2005) instruments. There are attempts to combine these space-based observations with the ground-based observations also (see for example Hariharan et al (2016)). All these spectrometers produce large datasets.…”

Section: Introductionmentioning

confidence: 99%

Automated Detection of Solar Radio Bursts Using a Statistical Method

et al. 2019

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Radio bursts from the solar corona can provide clues to forecast space weather hazards. After recent technology advancements, regular monitoring of radio bursts has increased and large observational data sets are produced. Hence, manual identification and classification of them is a challenging task. In this paper, we describe an algorithm to automatically identify radio bursts from dynamic solar radio spectrograms using a novel statistical method. We used e-CALLISTO radio spectrometer data observed at Gauribidanur observatory near Bangalore in India during 2013 -2014. We have studied the classifier performance using the receiver operating characteristics. Further, we studied type III bursts observed in the year 2014 and found that 75% of the observed bursts were below 200 MHz. Our analysis shows that the positions of the flare sites which are associated with the type III bursts with upper frequency cut-off 200 MHz

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“…The observations were carried out close to the local meridian transit time of the Sun (≈06:30 UT). For radio spectral data, we used observations with the Gauribidanur LOw-frequency Solar Spectrograph (GLOSS; Ebenezer et al, 2001aEbenezer et al, , 2007Kishore et al, 2014;Hariharan, Ramesh, Kathiravan, Abhilash, & Rajalingam, 2016), Gauribidanur RAdio Spectro-Polarimeter (GRASP, Hariharan et al, 2015;Kishore et al, 2015;Sasikumar Raja et al, 2013), and e-CALLISTO (Benz et al, 2009;Monstein et al, 2007). We also used data obtained with the Gauribidanur Radio Interferometric Polarimeter (GRIP, Ramesh & Sastry, 2005b;Ramesh et al, 2008).…”

Section: Observationsmentioning

confidence: 99%

New Results on the Direct Observations of Thermal Radio Emission from a Solar Coronal Mass Ejection

Ramesh

Kumari

Kathiravan

et al. 2021

Geophysical Research Letters

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Coronal mass ejections (CMEs) are large-scale and energetic eruptions in the solar atmosphere during which ≈ 10 12 -10 16 g of magnetized coronal plasma are ejected into the heliosphere at speeds ranging from ≈ 100 to 3,000 km/s (e.g., Vourlidas et al., 2010). They are mostly observed in whitelight using coronagraphs which use an occulter to block the bright light from the solar photosphere so that structures like CMEs can be observed with better contrast. But the size of the coronagraph occulters to date has always been larger than that of the photosphere. For example, in the Large Angle and Spectrometric Coronagraph C2 (LASCO C2, Brueckner et al., 1995) on board the Solar and Heliospheric Observatory (SOHO), the occulter covers a heliocentric distance (r) of ≈ 2.2 R ⊙ , where R ⊙ is the radius of the photosphere. This prevents observations of the corona present immediately off the solar limb, in addition to the corona above the solar disk. Radio observations are unique in this connection since there is no occulter. The radio emission associated with and/or from the CMEs can be divided into two classes, thermal and nonthermal (e.g., Vourlidas, 2004). In the nonthermal case, type IV radio bursts due to gyrosynchrotron and/or plasma emission from the electrons in the CME (

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High Dynamic Range Observations of Solar Coronal Transients at Low Radio Frequencies With a Spectro-Correlator

Cited by 19 publications

References 65 publications

Low‐Frequency Radio Observations of the “Quiet” Corona During the Descending Phase of Sunspot Cycle 24

Low‐Frequency Radio Observations of the “Quiet” Corona During the Descending Phase of Sunspot Cycle 24

Automated Detection of Solar Radio Bursts Using a Statistical Method

New Results on the Direct Observations of Thermal Radio Emission from a Solar Coronal Mass Ejection

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