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Browsing IIAP Publications by Title

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  • Diagnostics of a coronal hole and the adjacent quiet sun by the hinode/EUV Imaging Spectrometer (EIS) 
    Kayshap, P; Banerjee, D; Srivastava, A. K (Springer, 2015-10)
    A comparison between a coronal hole (CH) and the adjacent quiet Sun (QS) has been performed using the spectroscopic diagnostics of the Hinode/EUV Imaging Spectrometer (EIS). Based on spectral signatures, we identify the ...
  • Diagnostics of solar plasma using emission lines 
    Dwivedi, B. N (Indian Institute of Astrophysics, Bangalore, 1988)
    The spectroscopic techniques in the X- and EUV region to determine electron density and temperature of solar plasma have been presented. The line intensity ratios as a diagnostic probe of solar plasma from berrylium, boron, ...
  • Did IBN SINA Observe The Transit of Venus 1032 AD? 
    Kapoor, R. C (Indian National Science Academy, 2013-09)
    The Persian polymath Ab ū AīIbn Sīnā (980-1037 AD), known to early Western sources as Avicenna, records in one of his works, Compendium of the Almagest that ‘I say that I saw Venus as a spot on the surface of the sun’. ...
  • Dieterici gas as a unified model for dark matter and dark energy 
    Sivaram, C; Arun, K; Nagaraja, R (Springer, 2011-10)
    The dominance of dark energy in the universe has necessitated the introduction of a repulsive gravity source to make q0 negative. The models for dark energy range from a simple term to quintessence, Chaplygin gas, ...
  • Difference image analysis: extension to a spatially varying photometric scale factor and other considerations 
    Bramich, D. M; Horne, Keith; Albrow, M. D; Tsapras, Y; Snodgrass, C; Street, R. A; Hundertmark, M; Kains, N; Arellano Ferro, A; Figuera Jaimes, R; Giridhar, S (Oxford University Press on behalf of the Royal Astronomical Society, 2013-01-21)
    We present a general framework for matching the point-spread function (PSF), photometric scaling and sky background between two images, a subject which is commonly referred to as difference image analysis (DIA). We introduce ...
  • Difference of temperature between pole and equator of the sun 
    Das, A. K; Abhyankar, K. D (Nature Publishing Group, 1953-09)
    BothEmden's/sup1 old hydrodynamic solar theory and the more modern thermo-hydrodynamical solar theory due to Bjerknes/sup2 lead to a higher temperature at the poles than at the equator of the sun. Bjerknes's theory is, ...
  • Differences in heliographic positions and rotation velocities of sunspot groups from various observatories 
    Poljancic, I; Brajsa, R; Hrzina, D; Wohl, H; Hanslmeier, A; Potzi, W; Baranyi, T; Ozguc, A; Singh, J; Ruzdjak, V (Hvar Observatory, 2011)
    Measured positions of sunspot groups that differ in format, precision and observing procedure are collected from various data sets: GPR (Greenwich Photoheliographic Results), SOON/USAF/NOAA (Solar Optical Observing ...
  • Different Angles on Active Galaxies: Where are We with Regard to Unification? 
    Shastri, P (Astronomical Society of the Pacific, 2007-10)
    With the realization that orientation plays a dominant role in the appearance of active galaxies, much of AGN research has been worked into the operating framework of the �unified scheme,� wherein active galaxies are broadly ...
  • The different character of spectrum lines belonging to the same series 
    Royds, T (Indian Institute of Astrophysics, Bangalore, 1914-09-29)
  • The different character of spectrum lines belonging to the same series 
    Royds, T (IOP Publishing, 1915-03)
  • Different representations of a partially ionized plasma 
    Krishan, V (Indian Academy of Sciences, 2022-12)
    It is economical to devise ways and means to simplify a multi-species particle system. A partially ionized plasma consisting of electrons, ions and neutral particles can be described as a three-fluid, a two-fluid or a ...
  • Differential rotation of solar features and its variation as deduced from the "shock-transition model" of the solar cycle 
    Gokhale, M. H (Indian Institute of Astrophysics, 1979-11)
    From the topology of the two families of flux tubes in the shock-transition model of the solar cycle we predict the general nature of the differential rotation of: (i) sunspots and the small scale emission features in ...
  • Differential Rotation of the Solar Chromosphere: A Century-long Perspective from Kodaikanal Solar Observatory Ca II K Data 
    Mishra, Dibya Kirti; Routh, Srinjana; Jha, Bibhuti K; Chatzistergos, Theodosios; Basu, Judhajeet; Chatterjee, Subhamoy; Banerjee, D; Ermolli, Ilaria (American Astronomical Society, 2024-01-20)
    Chromospheric differential rotation is a key component in comprehending the atmospheric coupling between the chromosphere and the photosphere at different phases of the solar cycle. In this study, we therefore utilize the ...
  • Diffraction by ruled gratings with variable spacing: fundamental method of intensity calculation 
    Chatterjee, S; Vani, V. C; Haghighi, Rezvan R; Banyal, R. K (Optical Society of America, 2019-11-01)
    A regular diffraction grating produces intensity patterns that combine waves coming through equispaced slits, so that the waves emerging from any two neighboring slits have identical phase differences. In this paper, we ...
  • Diffraction limited imaging with large and moderate telescopes 
    Saha, S. K (World Scientific Publishing, 2007)
    This book deals with the fundamentals of wave optics, polarization, interference, diffraction, imaging, and the origin, properties, and optical effects of turbulence in the Earth's atmosphere. Techniques developed during ...
  • Diffuse echo bursts at 34.5 MHz 
    Subramanian, K. R (Indian Institute of Astrophysics, Bangalore, 1988)
    The solar radio bursts during their propagation towards the earth are refracted, scattered, reflected and absorbed. The combination of these effects play a role in determining the source size, position, brightness temperature ...
  • The Diffuse Radiation Field at High Galactic Latitudes 
    Akshaya, M. S; Murthy, J; Ravichandran, S; Henry, R. C; Overduin, J (IOP Publishing, 2018-08-10)
    We have used GALEX observations of the north and south Galactic poles to study the diffuse ultraviolet background at locations where the Galactic light is expected to be at a minimum. We find offsets of 230–290 photon units ...
  • Diffuse radiation from the Aquila Rift 
    Jyothy, S. N; Murthy, J; Karuppath, N; Sujatha, N. V (Oxford University Press on behalf of the Royal Astronomical Society, 2015-12-01)
    We present an analysis of the diffuse ultraviolet (UV) background in a low latitude region near the Aquila Rift based on observations made by the Galaxy Evolution Explorer (GALEX). The UV background is at a level of about ...
  • Diffuse radio emission from the coma cluster of galaxies at decametre wavelengths 
    Sastry, Ch. V; Shevgaonkar, R. K (Indian Academy of Sciences, 1983-03)
    We have observed the region of the Coma cluster at 34.5 MHz with a resolution of 26 arcmin × 40 arcmin. A map of the diffuse halo (Coma C) is presented. The size of the halo is found to be 54 arcmin × 30 arcmin. The position ...
  • The Diffuse Ultraviolet Foreground 
    Murthy, J (Springer, 2014-01)
    Ultraviolet observations from low Earth orbit (LEO) have to deal with a foreground comprised of airglow and zodiacal light which depend on the look direction and on the date and time of the observation. We have used all-sky ...

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