IIA Institutional Repository: Recent submissions

  • 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 ...
  • Instrument design for the observation of the sun at near IR wavelengths: (around 1.6 µ) 
    Aritra Chakrabarty (Indian Institute of Astrophysics, 2016-07)
    The H minus ions prevalent in the sub-photospheric level are found to have minimum opacity at around 1.63 m which makes this wavelength suitable for sub-photospheric observations . Some previous observations by Foukal ...
  • High precision full stokes spectropolarimetry of the sun as a star instrument design aspects 
    Souvik Bose (Indian Institute of Astrophysics, 2016-07)
    The sun is very interesting particularly because it is very dynamic. The magnetic field plays a major role in governing dynamics of the sun. Many interesting features like sunspots, flares, prominences, and Coronal Mass ...
  • Polarized line scattering theory with applications in astrophysical radiative transfer: a historical perspective 
    Nagendra, K. N (Astronomical Society of the Pacific, 2019-07)
    Ivan Hubený did fundamental work in the theory of partial frequency redistribution (PFR) and radiative transfer (RT). One of the most elegant works is the “theory of generalized redistribution functions (GRFs)†for ...
  • Quantitative astronomical spectroscopy in the post Saha equation period 
    Bhattacharyya, J. C (Saha Institute of Nuclear Physics, 2017-07)
    Several new questions of quantitatively estimating physical conditions on astronomical bodies had opened up after formulation of Saha Ionization Equation. The article first reviews the step by step progress in ...
  • Optical and GeV flux variations in Fermi blazars 
    Stalin, C. S (Astronomical Society of India, 2015-04)
    A large fraction of γ-ray emitting blazars show correlated flux variations in the optical and γ-ray bands with little or no time lag. However, in a minority of them, uncorrelated optical and γ-ray flux variations are seen. ...
  • The search for binary black holes in Seyferts with double peaked emission lines 
    Kharb, P; Mousumi Das; Subramanian, S; Paragi, Z (Astronomical Society of India, 2015-04)
    We discuss results from very long baseline interferometry (VLBI) observations of two Seyfert galaxies with double peaked emission lines in their SDSS optical spectra. Such AGN are potential candidates for the presence ...
  • Modelling the synchrotron light curves in recurrent novae V745 Scorpii and RS Ophiuchi 
    Kantharia, N. G; Dutta, P; Roy, N; Anupama, G. C; Chitale, A; Ishwara-Chandra, C; Prabhu, T. P; Ashok, N. M; Banerjee, D. P. K (Astronomical Society of India, 2015-02)
    In this paper, we present the synchrotron light curve at 610 MHz from the recurrent nova V745 Sco following its outburst on 6 February 2014. The system has been detected and periodically monitored with the Giant Metrewave ...
  • A model for relativistic disk emission, flow and variability 
    Mohan, Prashanth; Mangalam, A (Astronomical Society of India, 2015-04)
    Orbiting features near a black hole can cause variability in optical/UV and X-ray bands with quasi-periodic signatures. The variable flux is derived in Kerr geometry including the following relativistic effects: light ...
  • Lepto−Hadronic Origin of γ-ray Outbursts of 3C 279 
    Paliya, Vaidehi S; Diltz, C; Bottcher, M; Stalin, C. S; Buckley, D (Astronomical Society of India, 2015-03)
    The blazar 3C 279 exhibited a giant γ-ray outburst in 2013 December and 2014 April. Apart from the very fast γ-ray flux variability, the spectral nature of the flares were also found to vary significantly between these ...
  • Hard X-ray flux variations in AGN from NuSTAR 
    Priyanka Rani; Stalin, C. S (Astronomical Society of India, 2015-04)
    We present here our results on the hour like time scale Xray flux variations in a sample of active galactic nuclei using data from the Nuclear Spectroscopic Telescope Array (NuSTAR). We find that in the 3−79 keV band, ...
  • Study of core-collapse supernovae with the upcoming 4m international liquid mirror telescope at Devasthal, Nainital 
    Brajesh Kumar; Surdej, J; Hickson, P; Borra, E. F; Finet, F; Swings, J. P; Habraken, S; Pandey, S. B (Astronomical Society of India, 2015-03)
    We present an overview and status of the upcoming 4m International Liquid Mirror Telescope facility at Devasthal, Nainital and its uses for the study of core-collapse supernovae (CCSNe).
  • Opportunities for astrophysical science from the inner and outer solar system 
    Zemcov, Michael; Arcavi, Iair; Arendt, Richard G; Bachelet, Etienne; Beichman, Chas; Bock, James; Brandt, Pontus; Ranga Ram Chary; Cooray, Asantha; Dragomir, Diana; Gorjian, Varoujan; Harman, Chester E; Henry, Richard Conn; Lisse, Carey; Lubin, Philip; Matsuura, Shuji; McNutt, Ralph; Murthy, J; Poppe, Andrew R; Paul, Michael V; Reach, William T; Shvartzvald, Yossi; Street, R A; Symons, Teresa; Werner, Michael (American Astronomical Society, 2019-05)
    Astrophysical measurements away from the 1 AU orbit of Earth can enable several astrophysical science cases that are challenging or impossible to perform from Earthbound platforms, including: building a detailed understanding ...
  • Optical Design of the Dual Beam Imaging Polarimeter (DBIP) for the 1.3m JCB telescope in Kavalur 
    Pavankumar, K (Indian Institute of Astrophysics, 2016-07)
    Imaging Polarimetry of Extended sources is not very common. This project entitled "Dual Beam Imaging Polarimeter" is an attempt to build one for the 1.3m telescope in Kavalur. The Instrument will make use of the Wide field ...
  • Mid-infrared imager for the 2m Himalayan Chandra Telescope: feasibility, conceptual design and roadmap for implementation 
    Anwesh Kumar, M (Indian Institute of Astrophysics, 2015-08)
    Ground based observations in the Mid-infrared wavelength range has the advantages of greater penetrating power through interstellar gas and dust, ability to observe cooler objects, and less effect of atmospheric turbulence. ...
  • Edge sensor for segmented mirror telescopes 
    Varun Kumar (Indian Institute of Astrophysics, 2015-08)
    To address key research problems of astronomy, a large aperture telescope has become a need for every astronomical group around the globe. Optical telescopes with single monolithic primary mirror of 8m and above aperture ...
  • 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 ...

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