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Browsing by Author "Subramanian, K. R"

Browsing by Author "Subramanian, K. R"

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  • A low cost steerable radio-telescope 
    Sawant, H. S; Neri, J. A. C. F; Fernandes, F. C. R; Cecatto, J. R; Sankararaman, M. R; Faria, C; Stephany, S; Rosa, R. R; Andrade, M. C; Alonso, E. M. B; Ludke, E; Subramanian, K. R; Ramesh, R; Sundararajan, M. S; Ananthakrishnan, S; Swarup, G; Boas, J. W. V; Botti, L. C. L; Moron, C. E; Saito, J. H (Elsevier B. V., 2003)
    We present the technical characteristics of a low-cost radio telescope for solar/non solar observations at decimetric (1200–1700 MHz) and centimetric (2700 and 5000 MHz) wavelengths known as Brazilian Decimetric Array ...
  • Low frequency radio observations of the solar corona prior to the onset of a mass ejection event 
    Ramesh, R; Subramanian, K. R; Sastry, Ch. V (European Space Agency, 1999-10)
    It is well known that the halo CMEs originating on the visible hemisphere of the Sun could give rise to the severest terrestrial consequences. Recent studies carried out with the YOHKOH soft X-ray data by various authors ...
  • The low-frequency radio spectrum of the continuum emission from the undisturbed sun 
    Subramanian, K. R; Sastry, Ch. V (Indian Academy Sciences, 1988-12)
    The low-frequency radio spectrum of the continuum emission from the undisturbed Sun is determined for 24 days during the period 1985 May - September. It is found that the spectral index varied from +1.6 to +3.6 during this ...
  • Lunar Occultation Observations of the Microwave Sun During the Eclipse of October 24, 1995 
    Bagchi, J; Subramanian, K. R; Ebenezer, E; Gowda, N; Abdul Hameed, A. T (Indian Institute of Astrophysics, Bangalore, 1997)
    The interpretation of the lunar occultation data recorded at the microwave frequencies of 2025, 3.80 and 4.20 GHz from two stations during the October 24, 1995 solar eclipse in India is presented.
  • Metric Radio Observations and Ray-tracing Analysis of the Onset Phase of a Solar Eruptive Event 
    Kathiravan, C; Ramesh, R; Subramanian, K. R (University of Chicago Press, 2002-03)
    We report metric radio observations and the results obtained using two-dimensional ray-tracing analysis of the solar corona close to the onset phase of the exceptionally bright prominence eruption and the associated massive ...
  • A new digital spectrograph for observations of radio burst emission from the Sun 
    Ebenezer, E; Ramesh, R; Subramanian, K. R; Sundararajan, M. S; Sastry, Ch. V (EDP Sciences, 2001-03)
    A new digital spectrograph for obtaining a dynamic spectrum of radio burst emission from the Sun in the frequency range 30-80 MHz has been recently commissioned at the Gauribidanur Radio Observatory (Lat: 13degr ...
  • A new investigation of microbursts at meter-decameter wavelengths 
    Subramanian, K. R; Gopalswamy, N; Sastry, Ch. V (Kluwer Academic Publishers, 1993-02)
    The results of a new investigation of microbursts at meter-decameter wavelengths are reported. Several properties of microbursts reported earlier are confirmed, and some new properties, such as time profile characteristics, ...
  • Observations and interpretation of solar decameter type IIIb radio bursts 
    Krishan, V; Subramanian, K. R; Sastry, Ch. V (Kluwer Academic Publishers, 1980-06)
    Solar decameter bursts of Type IIIb are observed with a multichannel radiometer at wavelengths around 12m. The time and frequency resolutions were 10 ms and 100 kHz. Observations on the time structure of these bursts are ...
  • Observations of the Structure of Type-IIIb Radio Bursts 
    Sastry, Ch. V; Subramanian, K. R; Krishnan, V (International Astronomical Union, 1980)
  • Observations on the occultation of the radio source Tauras A by the solar corona during June 1971 
    Sastry, Ch. V; Subramanian, K. R (National Institute of Science Communication and Information Resources, 1974-09)
    Observations on the occultation of the radio source Tamas A (3C 144) during June 1971 at a wavelength of 12 m are presented. It is tentatively observed that there is no strong dependence between the amount of scattering and ...
  • Occultation of a solar active region at 1.5 GHz during the eclipse of November 3, 1994 
    Subramanian, K. R; Sawant, H. S; Fernandes, F. C. R; Cecatto, J. R (EDP Sciences, 2006-03)
    We observed the solar eclipse of November 3, 1994 with a 4-m diameter antenna and a radio spectrograph operating at 1.5 ± 0.05 GHz with a time resolution of 100 ms. Here we present the observations of the occultation of ...
  • On the correlation between exciter duration and decay constant of solar decameter Type III radio bursts 
    Subramanian, K. R; Krishan, V; Sastry, Ch. V (Kluwer Academic Publishers, 1981-04)
    It is observed that while there exists a strong correlation between the decay constant and the exciter duration for isolated type III radio bursts, it is absent for those type III radio bursts which are preceded by type ...
  • Post-flare pulsations in the 54–78 MHz frequency band 
    Subramanian, K. R; Ebenezer, E (Springer, 2003-12)
    Quasi-periodic pulsations with periods mostly around 13 s in the frequency range of 54-78 MHz have been observed following the first X2 flare occurring on 24 November 2000. Assuming an impulsively generated propagating MHD ...
  • Pulsating radio emission at decametre wavelengths from the sun 
    Sastry, Ch. V; Krishan, V; Subramanian, K. R (Indian Academy of Sciences, 1981-03)
    Observations on the pulsation pattern in the time profile of short duration solar radio bursts at decametre wavelengths are presented. The pulsations are found to be present predominantly in the saturation phase of the ...
  • Quasi - periodic pulsations at decameter wavelengths in the November 24, 2000 solar flare 
    Subramanian, K. R; Ebenezer, E (Astronomical Society of India, 2002-09)
    Spectral observations of the Sun in the frequency range of 54 to 78 MHz in the November 24, 2000 solar flare showed quasi - periodic pulsations with periods in the range of 11 - 19 seconds. YOHKOH images of this flare ...
  • Quasi-Periodicity in global solar radio flux at metric wavelengths during Noise Storms 
    Sundaram, G. A. S; Subramanian, K. R (Springer, 2004-08)
    We present observational results from studying the quasi-periodicities in global solar radio flux during periods of enhanced noise storm activity, over durations of 4 hr a day (`intra-day'' variations), observed at 77.5 ...
  • Radio and EUV measurements of the equatorial coronal hole of February 25, 1999 
    Subramanian, K. R; Sundaram, G. A. S (Astronomical Society of the Pacific, 2005)
    We present here the observations of the equatorial coronal hole made at 109 MHz on February 25, 1999 with the Gauribidanur Radioheliograph. The brightness temperature of this coronal hole is about 1:7£105 K.We compare our ...
  • Radio Emission Processes: Part I 
    Subramanian, K. R (Springer, 2010)
    This chapter provides an overview of the radio emission mechanisms in the Solar atmosphere. Incoherent (free - free emission and gyro - emission) and coherent (plasma emission and electron cyclotron maser emission) emission ...
  • Radio Observations of Compact Sources in the Outer Solar Corona 
    Ramesh, R; Subramanian, K. R; Sastry, Ch. V (Indian Institute of Astrophysics, Bangalore, 1997)
    We have observed radio emission from the solar corona at a frequency of 77 MHz during the total solar eclipse on October 24, 1995 from our observatory at Gauribidanur. Sources of angular sizes less than or equal to 1.5' ...
  • Solar spectral fine structure in 18 - 23 GHz band 
    Cecatto, J. R; Subramanian, K. R; Sawant, H. S (Brazilian Physical Society, 1999-09)
    On 30th June 1989 high sensitivity-spectral resolution observations of solar radio bursts were carried out in the frequency range of 18 - 23 GHz. The burst observed at 17:46 UT was different from the 60 bursts observed so ...

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