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Browsing by Author "Rangarajan, K. E"

Browsing by Author "Rangarajan, K. E"

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  • Effect of waves on resonance scattering polarization in solar atmosphere 
    Rangarajan, K. E (Kluwer Academic Publishers, 1999)
  • The effects of electron scattering on the Si II 1816 line in the solar chromosphere 
    Rangarajan, K. E; Rao, D. M (Springer-Verlag, 1991)
    We have considered the formation of Si II 1816 line in the solar chromosphere. The VAL model has been adopted as the input for the electron density and temperature. These preliminary calculations show that there are ...
  • The effects of non-coherent electron scattering on spectral line formation 
    Rangarajan, K. E; Mohan Rao, D; Peraiah, A (Royal Astronomical Society, 1991-06)
    Spectral line profiles from a plane-parallel homogeneous atmosphere have been calculated for the complete and partial redistribution mechanisms (CRD and PRD) including coherent and noncoherent electron scattering. It is ...
  • Effects of partial frequency redistribution functions R(II), R(III) and R(V) on source functions 
    Mohan Rao, D; Rangarajan, K. E; Peraiah, A (Indian Academy of Sciences, 1984-06)
    The effects of partial frequency redistribution on the formation of spectral lines have been studied. The angle-averaged R(II), R(III) and R(V) types of redistribution with isotropic phase function have been considered. ...
  • Effects of redistribution with dipole scattering on line source functions 
    Peraiah, A; Rangarajan, K. E (Indian Academy of Sciences, 1981-09)
    The partial frequency redistribution function for zero natural line width and dipole scattering is used to obtain a simultaneous solution of the statistical equilibrium and line transfer equations in the comoving frame of ...
  • Effects of stimulated emission on radiative transfer with partial redistribution 
    Rangarajan, K. E; Mohan Rao, D; Peraiah, A (The European Southern Observatory, 1990-08)
    The non-LTE line transfer with stimulated emission is studied. Stimulated emission is important for red transitions in hot stars and infrared transitions in cool stars. The deviation of the absorption and emission profiles ...
  • Effects of Velocities on Ca II H and K Lines 
    Rangarajan, K. E; Mohan Rao, D; Peraiah, A (Indian Institute of Astrophysics, Bangalore, 1981)
    Ca II H and K (3968, 3933) and infrared triplet lines lamda lamda lamda 8498, 8662, 8542 were calculated in a very slowly expanding medium. Five level atom with continuum was considered. Radiative transfer equation and ...
  • An efficient modulation scheme for dual beam polarimetry 
    Nagaraju, K; Ramesh, K. B; Sankarasubramanian, K; Rangarajan, K. E (Astronomical Society of India, 2007-09)
    An eight stage balanced modulation scheme for dual beam polarimetry is presented in this paper. The four Stokes parameters are weighted equally in all the eight stages of modulation resulting in total polarimetric efficiency ...
  • Fine image motion controler for Kodaikanal tunnel telescope 
    Thulasidharen, K. C; Prabhu, K; Rangarajan, K. E; Vasantharaju, N; Prabhu Ramkumar, B (Indian Institute of Astrophysics, 2013-05-06)
    Automation of the spectropolarimetric observations at Kodaikanal tunnel telescope needs placement of the Sun's image on the spectrograph slit and scanning it across the region of interest. This requirement can be achieved ...
  • Full-disk synoptic observations of the chromosphere using Hα telescope at the Kodaikanal Observatory 
    Ravindra, B; Prabhu, K; Rangarajan, K. E; Bagare, S. P; Singh, J; Kemkar, P. M. M; Thulasidharen, K. C; Gabriel, F; Selvendran, R (IOP Publishing, 2016-08)
    This paper reports on the installation and observations of a new solar telescope installed on 2014 October 7 at the Kodaikanal Observatory. The telescope is a refractive type equipped with a tunable Lyot Hα filter. A CCD ...
  • 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 ...

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