IIA Institutional Repository

Browsing by Author "Sasikumar Raja, K"

Browsing by Author "Sasikumar Raja, K"

Sort by: Order: Results:

  • Amplitude of solar wind density turbulence from 10 to 45 R⊙ 
    Sasikumar Raja, K; Ingale, M; Ramesh, R; Subramanian, P; Manoharan, P. K; Janardhan, P (American Geophysical Union, 2016-12)
    We report on the amplitude of the density turbulence spectrum ( urn:x-wiley:jgra:media:jgra53108:jgra53108-math-0001) and the density modulation index (δN/N) in the solar wind between 10 and 45R⊙. We derive these quantities ...
  • Automated Detection of Solar Radio Bursts Using a Statistical Method 
    Singh, Dayal; Sasikumar Raja, K; Subramanian, Prasad; Ramesh, R; Monstein, Christian (Springer, 2019-08)
    adio 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 datasets are produced. ...
  • Calibration of VELC detectors on-board Aditya-L1 mission 
    Mishra, Shalabh; Sasikumar Raja, K; Sanal Krishnan, V. U; Venkata Suresh, Narra; Hegde, Bhavana; Utkarsha, D; Priyal, M; Pawan, Kumar; Natarajan, V; Prasad, B. R; Singh, J; Kamath, P. U; Kathiravan, S; Vishnu, T; Suresha; Savarimuthu, P; Desai, Jalshri H; Kumaran, Rajiv; Sagar, Shiv; Kumar, Sumit; Bamrah, Inderjeet Singh; Amit Kumar (Springer Nature, 2024-04)
    Aditya-L1 is the first Indian space mission to explore the Sun and solar atmosphere with seven multi-wavelength payloads, with Visible Emission Line Coronagraph (VELC) being the prime payload. It is an internally occulted ...
  • Design and Performance of a Low-Frequency Cross-Polarized Log-Periodic Dipole Antenna 
    Sasikumar Raja, K; Kathiravan, C; Ramesh, R; Rajalingam, M; Barve, Indrajit V (IOP Publishing, 2013-07)
    We report the design and performance of a cross-polarized log-periodic dipole (CLPD) antenna for observations of polarized radio emission from the solar corona at low frequencies. The measured isolation between the two ...
  • Development of an antenna system to observe the circularly polarized radio emission from the solar corona at low frequencies 
    Sasikumar Raja, K (Indian Institute of Astrophysics, 2010-07)
    The corona is the outer most atmosphere of the Sun, overlying the photosphere and the chromosphere. It extends to several millions of kilometers into space and is about 106 times fainter compared to the photosphere. At ...
  • Dissipation scale lengths of solar wind turbulence 
    Sasikumar Raja, K; Subramanian, P; Ingale, M; Ramesh, R (IOP Publishing, 2019-02-10)
    Knowing the lengthscales at which turbulent fluctuations dissipate is key to understanding the nature of weakly compressible magnetohydrodynamic turbulence. We use radio wavelength interferometric imaging observations ...
  • Eruption of the EUV Hot Channel from the Solar Limb and Associated Moving Type IV Radio Burst 
    Vemareddy, P; Demoulin, P; Sasikumar Raja, K; Zhang, J; Gopalswamy, N; Vasantharaju, N (American Astronomical Society, 2022-03-01)
    Using the observations from the Solar Dynamics Observatory, we study an eruption of a hot-channel flux rope (FR) near the solar limb on 2015 February 9. The pre-eruptive structure is visible mainly in EUV 131 Å images, ...
  • An estimate of the magnetic field strength associated with a solar coronal mass ejection from low frequency radio observations 
    Sasikumar Raja, K; Ramesh, R; Hariharan, K; Kathiravan, C; Wang, T. J (IOP Publishing, 2014-11-20)
    We report ground based, low frequency heliograph (80 MHz), spectral (85-35 MHz), and polarimeter (80 and 40 MHz) observations of drifting, non-thermal radio continuum associated with the "halo" coronal mass ejection that ...
  • Low-frequency Observations of Transient Quasi-periodic Radio Emission from the Solar Atmosphere 
    Sasikumar Raja, K; Ramesh, R (IOP Publishing, 2013-09-20)
    We report low-frequency observations of quasi-periodic, circularly polarized, harmonic type III radio bursts whose associated sunspot active regions were located close to the solar limb. The measured periodicity of the ...
  • Low-frequency radio observations of picoflare category energy releases in the solar atmosphere 
    Ramesh, R; Sasikumar Raja, K; Kathiravan, C; Satya Narayanan, A (IOP Publishing, 2013-01-10)
    We report low-frequency (80 MHz) radio observations of circularly polarized non-thermal type I radio bursts ("noise storms") in the solar corona whose estimated energy is ~1021 erg. These are the weakest energy release ...
  • Preparing for solar and heliospheric science with the SKAO: An Indian perspective 
    Oberoi, Divya; Bisoi, Susanta Kumar; Sasikumar Raja, K; Kansabanik, Devojyoti; Mohan, Atul; Mondal, Surajit; Sharma, Rohit (Indian Academy of Sciences, 2023-06)
    The Square Kilometre Array Observatory (SKAO) is perhaps the most ambitious radio telescope envisaged yet. It will enable unprecedented studies of the Sun, corona and heliosphere and help to answer many of the outstanding ...
  • Radio polarization studies of the solar corona at low frequencies 
    Sasikumar Raja, K (Indian Institute of Astrophysics, 2014-10)
    The radio telescopes that are presently in operation specifically to study the Sun are limited. We have: (1) the Nobeyama radioheliograph in Japan operating at 17 and 34 GHz; (2) the Nan¸cay radioheliograph in France ...
  • Solar coronal magnetic fields and sensitivity requirements for spectropolarimetry channel of VELC onboard Aditya-L1 
    Sasikumar Raja, K; Venkata Suresh, Narra; Singh, J; Prasad, B. R (Elsevier, 2022-01-01)
    Understanding solar coronal magnetic fields is crucial to address the long-standing mysteries of the solar corona and solar wind. Although routine photospheric magnetic fields (MFs) are available for decades, coronal MFs ...
  • Spectral Analysis of Solar Radio Type III Bursts from 20 kHz to 410 MHz 
    Sasikumar Raja, K; Maksimovic, Milan; Kontar, Eduard P; Bonnin, Xavier; Zarka, Philippe; Lamy, Laurent; Reid, Hamish; Vilmer, Nicole; Lecacheux, Alain; Krupar, Vratislav (IOP Publishing, 2022-01-10)
    We present the statistical analysis of the spectral response of solar radio type III bursts over the wide frequency range between 20 kHz and 410 MHz. For this purpose, we have used observations that were carried out using ...
  • A Statistical Study of Low-Frequency Solar Radio Type III Bursts 
    Mahender, A; Sasikumar Raja, K; Ramesh, R; Panditi, V; Monstein, C; Yellaiah, G (Springer, 2020-11)
    We have studied low-frequency (45 – 410 MHz) type III solar radio bursts observed using the e-Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Observatory (e-CALLISTO) spectrometer ...
  • Trends and characteristics of high-frequency type II bursts detected by CALLISTO spectrometers 
    Umuhire, A. C; Uwamahoro, J; Sasikumar Raja, K; Kumari, A; Monstein, C (Elsevier B.V., 2021-10-15)
    Solar radio type II bursts serve as early indicators of incoming geo-effective space weather events such as coronal mass ejections (CMEs). In order to investigate the origin of high-frequency type II bursts (HF type II ...
  • Turbulent Density Fluctuations and Proton Heating Rate in the Solar Wind from 9-20 R 
    Sasikumar Raja, K; Subramanian, P; Ramesh, R; Vourlidas, Angelos; Ingale, M (IOP Publishing, 2017-12)
    We obtain scatter-broadened images of the Crab Nebula at 80 MHz as it transits through the inner solar wind in 2017 and 2016 June. These images are anisotropic, with the major axis oriented perpendicular to the radially ...
  • Turbulent proton heating rate in the solar wind from 5–45 R⊙ 
    Sasikumar Raja, K; Subramanian, P; Ingale, M; Ramesh, R; Maksimovic, Milan (IOP Publishing, 2021-06-20)
    Various remote sensing observations have been used so far to probe the turbulent properties of the solar wind. Using the recently reported density modulation indices that are derived using angular broadening observations ...
  • Two-stage evolution of an extended C-class eruptive flaring activity from sigmoid active region NOAA 12734: SDO and Udaipur-CALLISTO observations 
    Joshi, B; Mitra, P. K; Bhattacharyya, R; Upadhyay, K; Oberoi, Divya; Sasikumar Raja, K; Monstein, Christian (Springer, 2021-06)
    In this article, we present a multi-wavelength investigation of a C-class flaring activity that occurred in the active region NOAA 12734 on 8 March 2019. The investigation utilizes data from the Atmospheric Imaging Assembly ...

Search DSpace

Browse

My Account