IIA Institutional Repository: Recent submissions

  • Development of cross-polarized log-periodic dipole antenna for low frequency radio spectral observations 
    Anshu Kumari (Indian Institute of Astrophysics, 2015-07)
    The solar coronal mass ejections (CMEs) play a direct and vital role in deciding the space weather, so it becomes inevitable to study their dynamical properties in the lower corona (i.e., over the radial distance range: ...
  • Towards radial velocity measurements with iodine absorption cell on VBT Echelle Spectrograph 
    Sireesha, C (Indian Institute of Astrophysics, 2015-08)
    Essentially all information about astronomical objects outside the solar system reach us via light, i.e., the electromagnetic radiation. White light is composed of many wavelengths which are not resolved into their ...
  • Development of an FPGA based photon counting detector 
    Ambily, S (Indian Institute of Astrophysics, 2014-08)
    The UV photon event rate is very low in the near space region and we need to have a very sensitive detector to discriminate between the noise and actual signal. Photon counting method is usually used to detect such weak ...
  • Development of SHABAR for estimating atmospheric scintillation 
    Phanindra, D. V. S (Indian Institute of Astrophysics, 2014-08)
    Electromagnetic radiation from Sun and stars suffers from the turbulence in earth atmosphere. The turbulence changes the complex refractive index of air which in turn modifies the electromagnetic signal. This condition is ...
  • Solar imaging and image processing : tolerance analysis of SUIT optics and implementation of different image processing approaches 
    Chatterjee, Subhamoy (Indian Institute of Astrophysics, 2014-07)
    Imaging sun in different wavelengths is invaluable for understanding its dynamic aspects and relevent impacts on space weather. The atmosphere of the Sun presents a number of puzzling physical phenomena of great importance. ...
  • Beam-former for single beam, total power mode observations with Gauribidanur Radioheliograph 
    Mugundhan, V (Indian Institute of Astrophysics, 2014-08)
    The Gauribidanur RadioheliograPH (GRAPH) in its present configuration is operated in the interferometer mode over the frequency range 30-100 MHz. It is proposed to design a beam-former unit for use with the GRAPH so that ...
  • Scientometric Portrait of Nobel Laureate Rainer Weiss 
    Mohan, B. S; Kumbar, M; Prabahar, P (Academic Book Publishers, 2017-03)
    The paper presents qualitative aspects of the research communications of Nobel Laureate Rainer Weiss based on 224 journal articles published during the publication phase of 1957-2017. This study has explored different ...
  • 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 ...
  • Capacitive edge sensor and sensor electronics for segmented mirror telescopes 
    Sreekanth Reddy, V (Indian Institute of Astrophysics, 2014-08)
    Edge sensors are high precision displacement sensors used in segmented mirror telescope to measure relative displacement between two mirror segments. An edge sensor based on parallel plate capacitor is being used in Keck ...
  • Analytical modelling of Thirty Meter Telescope polarization 
    Ramya, M. Anche (Indian Institute of Astrophysics, 2014-08)
    The polarization introduced due to TMT telescope optics is studied using an analytical model. Mueller matrices are also generated for each optical element using Zemax based on which the instrumental polarization due to ...
  • Partial Redistribution Theory and its Applications in the Interpretation of the Second Solar Spectrum 
    Nagendra, K. N (Astronomical Society of the Pacific, 2014-10)
    In this review we first describe briefly the techniques to formulate partial redistribution (PRD) matrices for polarized line scattering on atoms. These matrices have to be formulated by either semi-classical or quantum ...
  • Intrinsically Polarized Blend Lines 
    Sowmya, K; Nagendra, K. N; Sampoorna, M (Astronomical Society of the Pacific, 2014-10)
    The Second Solar Spectrum formed by coherent scattering processes in the Sun, is highly structured. It is characterized by numerous blend lines, both intrinsically polarizing and depolarizing, superposed on the background ...
  • A Co-Phasing technique for segmented mirror telescopes 
    Jacob, A (Indian Institute of Astrophysics, 2014-08)
    We are in an era where astronomy had taken steps to build giant telescope which have optics of size more than 10m, we can commonly call them ELTs or Extremely Large Telescopes. Due to various reasons like cost, ease of ...
  • The Role of Quantum Interference and Partial Redistribution in the Solar Ba II D2 4554 Ã… Line 
    Smitha, H. N; Nagendra, K. N; Stenflo, J. O; Sampoorna, M (Astronomical Society of the Pacific, 2014-10)
    The Ba ii D2 line at 4554 Å is a good example, where the F-state interference effects due to the odd isotopes produce polarization profiles, which are very different from those of the even isotopes that do not exhibit ...
  • Electron Scattering Redistribution Effect on Atomic Line Polarization 
    Supriya, H. D; Nagendra, K. N; Ravindra, B; Sampoorna, M (Astronomical Society of the Pacific, 2014-10)
    The scattering of line photons on free electrons modifies the polarization of the atomic spectral lines. Hence it is important to treat scattering by electrons as a redistribution process and to study in detail its effect ...
  • Studies on Carbon-Enhanced Metal-Poor (CEMP) stars 
    Drisya, K (Indian Institute of Astrophysics, 2015-03)
    Chemical composition of metal-poor stars are crucial to develop an understanding of the nature of the earliest stars formed in the universe, the nucleosynthesis events associated with them, as well as, to redefine the ...
  • Scattering polarization with Paschen-Back effect as a tool to diagnose the magnetic structuring of the solar atmosphere 
    Sowmya, K (Indian Institute of Astrophysics, 2016-03)
    The Sun is a unique physical laboratory in which the various domains of physics inaccessible to laboratories on earth can be studied in great detail. Its proximity allows us to understand it in great depths. George Ellery ...
  • Exploration of the second solar spectrum through polarimetric studies 
    Supriya, H. D (Indian Institute of Astrophysics, 2016-03)
    The discovery of Zeeman effect opened a new window to observe the Sun. It enabled to understand the magnetic field which is one of the basic features that govern different physical processes on the Sun. These magnetic ...
  • Magnetoconvective flows and waves in the lower solar atmosphere 
    Sangeetha, C. R (Indian Institute of Astrophysics, 2017-01)
    Sun has complex magnetic features like sunspots, magnetic bright points, plages, network fields, filaments, etc. These complex magnetic features are found to be associated with various observed dynamical phenomenons like ...
  • On the coupling between lower and upper atmosphere of the Sun 
    Samanta, T (Indian Institute of Astrophysics, 2017-01)
    The thesis is focused on the study of the small-scale transients and waves as seen in the different layers of the solar atmosphere and the coupling between the different layers. The unique high resolution data obtained ...

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