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Browsing by Author "Kumar, P"

Browsing by Author "Kumar, P"

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  • The Energy Dependence of the Photoelectric Attenuation Coefficient of Substances 
    Chatterjee, S; Vyas, A; Ravanfar Haghighi, R; Kumar, P (Global Center for Advanced Research in Biomedical Physics and Biomedical Engineering, 2011)
    Introduction: The photoelectric attenuation coefficient of substances is known to depend upon the energy E of the photon and the effective atomic number of substances (Zeff) as (Zeff x/Ey). No definitive values about ...
  • Multi-epoch intranight optical monitoring of eight radio-quiet BL Lac candidates 
    Kumar, P; Gopal-Krishna; Stalin, C. S; Chand, H; Srianand, R; Petitjean, P (Oxford University Press on behalf of the Royal Astronomical Society, 2017-10)
    For a new sample of eight weak-line quasars (WLQs) we report a sensitive search in 20 intranight monitoring sessions, for blazar-like optical flux variations on hour-like and longer time-scale (day/month/year-like). The ...
  • Polarimetric and spectroscopic study of radio quiet weak emission line quasars 
    Kumar, P; Chand, H; Srianand, R; Stalin, C. S; Petitjean, P; Gopal-Krishna (Oxford University Press on behalf of the Royal Astronomical Society, 2018-10)
    A small subset of optically selected radio-quiet quasars showing weak or no emission lines may turn out to be the elusive radio-quiet BL Lac objects, or simply be radio-quiet QSOs with a still-forming/shielded broad line ...
  • Probing the central engine and environment of AGN using ARIES 1.3-m and 3.6-m telescopes 
    Chand, H; Rakshit, S; Jalan, P; Ojha, V; Srianand, R; Vivek, M; Mishra, S; Omar, A; Kumar, P; Joshi, R; Gopal Krishna; Kumar, R (Societe Royale des Sciences de Liege, 2018-04)
    : We discuss three long term observational programmes to probe the central engine and environment of active galactic nuclei (AGN) using the recently installed ARIES 1.3-m and 3.6-m telescopes. The first programme is on ...
  • Sunspot drawings at Kodaikanal Observatory: a representative results on hemispheric sunspot numbers and area measurements 
    Ravindra, B; Kumaravel, P; Selvendran, R; Samuel, Joyce; Kumar, P; Nancy Jassoria; Navneeth, R. S (Springer, 2020-01)
    The importance of the periodicity in sunspot appearance was well recognized by the mid-19th century. Several observatories around the globe have made the record of sunspots in the form of drawings and preserved them safely ...

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