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Browsing by Author "Rangarajan, K. E"

Browsing by Author "Rangarajan, K. E"

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  • Ground Based Microwave Radiometric Technique in Remote Sensing 
    Rangarajan, K. E; Varghese, B. A (Astronomical Society of India, 2003)
    As an important tool of atmospheric remote sensing, microwave radiometers are used for temperature profiling and vapor and liquid column measurements. In addition, ice water path can be retrieved using radiometer observations. ...
  • Hα full line spectropolarimetry as diagnostics of chromospheric magnetic field 
    Nagaraju, K; Sankarasubramanian, K; Rangarajan, K. E (Indian Academy of Sciences, 2020-12)
    Analysis of spectropolarimetric observations of two circular sunspots located close to disk centre in Hα (6562.8 Å) and Fe i (6569.22 Å) is presented in this paper. The corresponding active region numbers areNOAA 10940 and ...
  • Magnetic and velocity properties of G-band bright points around a pore 
    Rangarajan, K. E; Sankarasubramanian, K; Nagaraju, K (Astronomical Society of the Pacific, 2009-06)
    Physical properties of G-band bright points (GBPs) surrounding a pore are studied using observations spanning from photosphere to chromosphere. The magnetic field strengths obtained in these bright points are of the order ...
  • Measurement of solar vector magnetic fields using Kodaikanal tower telescope 
    Sankarasubramanian, R; Rangarajan, K. E; Ramesh, K. B (Astronomical Society of India, 2002)
    A Stokes polarimeter was built at the Kodaikanal Tower Telescope to study the vector field map of active regions like sunspot using the well known Fe I lines 6301.5 Å and 6302.5 Å lines. The Mueller matrix of the polarimeter ...
  • Molecular Line Polarization in the Solar Atmosphere: MGH Lines 
    Mohan Rao, D; Rangarajan, K. E (The American Astronomical Society, 1999-10)
    The polarimetric observations of the quiet Sun show linear polarization in molecular lines of C_2, MgH, etc. The molecular lines are very faint in the intensity spectrum. We propose that the polarization is caused by ...
  • Non-conservative Rayleigh scattering in a finite atmosphere - II. Polarization in telluric lines 
    Mohan Rao, D; Rangarajan, K. E; Abhyankar, K. D (Astronomical Society of India, 1995)
    We consider non-conservative Rayleigh scattering in finite atmospheres and study the polarization in the molecular lines both in the transmitted and reflected sunlight. We first investigate the parameterized models to ...
  • Non-conservative Rayleigh scattering in a finite atmosphere. I. Polarization of skylight 
    Rangarajan, K. E; Mohan Rao, D; Abhyankar, K. D (Astronomical Society of India, 1994)
  • Observing conditions for optical astronomy at Leh 
    Singh, J; Bhattacharyya, J. C; Babu, G. S. D; Ashoka, B. N; Appakutty, M; Rangarajan, K. E; Kutty, K. N; Moorthy, V; Selvakumar, G; Michael, P; Muniyandi, A; Gabriel, F (Astronomical Society of India, 1989-09)
    The sky and atmospheric conditions at Leh have been monitored since 1984 with a view to determining its suitability as a site for a high-altitude observatory. During May-November, 1987, relative humidity and other parameters ...
  • On the performance of a dual-beam polarimeter at Kodaikanal tower telescope 
    Nagaraju, K; Sankarasubramanian, K; Rangarajan, K. E; Ramesh, K. B; Singh, J; Devendran, P; Hariharan (Astronomical Society of India, 2008-09)
    Calibration and characterization of a dual-beam polarimeter installed at Kodaikanal Tower Telescope (KTT) for spectropolarimetric observations are presented in this paper. It was found that a slit width of 48 μ is optimum ...
  • On the Weakening of the Chromospheric Magnetic Field in Active Regions 
    Nagaraju, K; Sankarasubramanian, K; Rangarajan, K. E (The American Astronomical Society, 2008-05)
    Simultaneous measurement of line-of-sight (LOS) magnetic and velocity fields at the photosphere and chromosphere are presented. The Fe i line at λ6569 and Hα at λ6563 are used for deriving the physical parameters at ...
  • Parametric Study of Molecular Line Polarization in the Solar Atmosphere 
    Rangarajan, K. E; Mohan Rao, D (Indian Academy of Sciences, 2000-12)
  • Photon escape probabilities in expanding atmospheres 
    Peraiah, A; Rangarajan, K. E; Mohan Rao, D (Indian Academy of Sciences, 1981-03)
    A comparison of mean number of scatterings and escape probabilities has been made in isotropic scattering and dipole scattering by using the angle-averaged partial frequency redistribution functionR I. We have solved the ...
  • Polarized resonance line transfer with collisional redistribution 
    Mohan Rao, D; Rangarajan, K. E (European Southern Observatory, 1993-07)
  • Preliminary analysis of the broad he i emission lines in R CrB 
    Surendiranath, R; Rangarajan, K. E; Kameswara Rao, N (D. Reidel Publishing Co, 1986)
  • Resonance line polarization in the presence of wave motion 
    Rangarajan, K. E (European Southern Observatory, 1997-04)
    The effect of wave velocity on resonance line polarization is studied. We assumed a photosphere - chromosphere type of temperature structure for the atmosphere with plane parallel symmetry. The "Discrete Space Theory ...
  • Simulation of multiple aperture synthesis 
    Saha, S. K; Jayarajan, A. P; Rangarajan, K. E; Chatterjee, S (European Space Observatory, 1988)
    In view of the importance of multiple aperture synthesis in optical astronomy, a computer simulation of the same is demonstrated. The fringe patterns obtained through the aperture mask of six and nine holes arranged ...
  • Solar astronomy at high altitude 
    Hasan, S. S; Bagare, S. P; Rangarajan, K. E (Indian National Science Academy, 2014-11)
    A major project called the National Large Solar Telescope (NLST) has been proposed for pursuing Solar Astronomy at High Altitude. The project envisages the development of a state-of-the-art 2-m class telescope to carry ...
  • Solar G-band observations at Merak, Leh/Ladakh 
    Vasantharaju, N; Dorjey, N; Ravindra, B; Prabhu, K; Rangarajan, K. E; Prabhu Ramkumar, B; Sankarasubramanian, K (Indian Institute of Astrophysics, 2012)
    G-band observations are important for the study of dynamics of magnetic features in the solar photosphere and they are carried out using large telescopes, larger than 30 cm. We installed a 40 cm DFM telescope at one of ...
  • Spectropolarimetry of an active region at the photosphere and chromosphere 
    Nagaraju, K; Sankarasubramanian, K; Rangarajan, K. E (Astronomical Society of the Pacific, 2009-06)
    Initial results on the simultaneous spectropolarimetric observations of an active region at the photosphere and chromosphere are presented. For this purpose, the Fe I line at λ6569 and the H I at λ6563 (Hα) are used. ...
  • Spectropolarimetry with the NLST 
    Sankarasubramanian, K; Hasan, S. S; Rangarajan, K. E (Springer, 2010)
    India’s National Large Solar Telescope (NLST) will provide opportunities to observe the Sun with high spatial, spectral, and polarimetric resolution. The large aperture also enables high-cadence spectropolarimetry with ...

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