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Browsing by Author "Singh, J"

Browsing by Author "Singh, J"

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  • Calcium K-line profiles as a function of latitude and solar cycle phase 
    Singh, J (Kluwer Academic Publishers, 1990)
  • The calcium K-line profiles as function of latitude and solar cycle phase 
    Singh, J (Elsevier, 2002-05)
    We have monitored the Calcium K-line profiles on daily basis at all the latitudes while integrating the spectrum over the visible longitudes of the Sun by moving a 340 mm solar image at a uniform speed in the E-W direction. ...
  • Calibration of VELC detectors on-board Aditya-L1 mission 
    Mishra, Shalabh; Sasikumar Raja, K; Sanal Krishnan, V. U; Venkata Suresh, Narra; Hegde, Bhavana; Utkarsha, D; Priyal, M; Pawan, Kumar; Natarajan, V; Prasad, B. R; Singh, J; Kamath, P. U; Kathiravan, S; Vishnu, T; Suresha; Savarimuthu, P; Desai, Jalshri H; Kumaran, Rajiv; Sagar, Shiv; Kumar, Sumit; Bamrah, Inderjeet Singh; Amit Kumar (Springer Nature, 2024-04)
    Aditya-L1 is the first Indian space mission to explore the Sun and solar atmosphere with seven multi-wavelength payloads, with Visible Emission Line Coronagraph (VELC) being the prime payload. It is an internally occulted ...
  • A century of solar Ca ii measurements and their implication for solar UV driving of climate 
    Foukal, P; Bertello, L; Livingston, W. C; Pevtsov, A. A; Singh, J; Tlatov, A. G; Ulrich, R. K (Springer, 2009-04)
    Spectroheliograms and disk-integrated flux monitoring in the strong resonance line of Ca ii (K line) provide the longest record of chromospheric magnetic plages. We compare recent reductions of the Ca ii K spectroheliograms ...
  • Chromospheric CA II K-line variations in the sun as a star over a solar cycle 
    Sivaraman, K. R; Singh, J; Bagare, S. P; Gupta, S. S (American Astronomical Society, 1987-02)
    The disk-averaged Ca II K profiles obtained at the Kodaikanal solar tower telescope for the period 1969-1984 are used to study the chromospheric variations in the sun as a star. The 1A index shows increases of 18 and 28 ...
  • The Chromospheric Network - (A) Network Evolution Viewed as a Diffusion Process 
    Srikanth, R; Singh, J; Raju, K. P (Kluwer Academic Publishers, 1999-03)
    Autocorrelation and cross-correlation techniques have been applied to obtain quantitative information about the dynamics of magnetic flux on the solar surface. The speed of network magnetic elements and the diffusion ...
  • The chromospheric network: Dependence of cell lifetime on length-scale 
    Srikanth, R; Raju, K. P; Singh, J (Kluwer Academic Publishers, 1999-02)
    A time series of CaiiK filtergrams of the chromosphere was used to study the relationship between correlation lifetimes and autocorrelation length scales. The form of the lifetime-scale relation is inferred by comparing ...
  • Chromospheric variations with solar cycle phase using imaging and spectroscopic studies 
    Sindhuja, G; Singh, J; Priyal, M (Oxford University Press on behalf of the Royal Astronomical Society, 2015-04-11)
    Spectroscopic observations of Sun in Ca-K line profile were made as a function of latitude and integrated over the visible 180◦ longitude at the Kodaikanal observatory since 1985. The spectroheliograms of the Sun in Ca-K ...
  • Clues to the mode of excitation of Fe X ions in the solar corona from the 1980 eclipse observations 
    Singh, J (Springer, 1985-02)
    The line and continuum intensities deduced from the multislit spectra of the (Fe X) coronal emission line taken at the 1980 eclipse are used to discuss the relative roles of radiative and collisional-excitation mechanisms. ...
  • Comparison among Ca II K spectroheliogram time series with an application to solar activity studies 
    Ermolli, I; Solanki, S. K; Tlatov, A. G; Krivova, N. A; Ulrich, R. K; Singh, J (Institute of Physics, 2009-06)
    Various observatories around the globe started regular full-disk imaging of the solar atmosphere in the Ca II K line in the early decades of the 20th century. The archives made by these observations have the potential of ...
  • Comparison of computed fluxes for Fe X and Fe XIV lines with observed values at 1980 eclipse 
    Raju, P. K; Singh, J (Kluwer Academic Publishers, 1987-09)
    Fluxes have been computed for Fex (6374 Å) and Fe xiv (5303 Å) lines as a function of solar radii and at various coronal tempratures. The electron density derived from the white light corona during the total solar eclipse ...
  • Complex Variations in the Line-Intensity Ratio of Coronal Emission Lines with Height above the Limb 
    Singh, J; Sakurai, T; Ichimoto, K; Watanabe, T (IOP Publishing, 2004-12-10)
    We obtained spectroscopic observations simultaneously in pairs of coronal emission lines, one line being [Fe X] λ6374 and the other line being [Fe XI] λ7892, [Fe XIII] λ10747, or [Fe XIV] λ5303, and we studied the variations ...
  • Correlation between sunspot number and Ca II K emission index 
    Bertello, L; Pevtsov, A; Tlatov, A; Singh, J (Springer, 2016-11)
    Long-term synoptic observations in the resonance line of Ca II K constitute a fundamental database for a variety of retrospective analyses of the state of the solar magnetism. Synoptic Ca II K observations began in late ...
  • The Correlation Lifetimes of Chromospheric CA II K Network Cells 
    Raju, K. P; Srikanth, R; Singh, J (Springer, 1998-03)
    The lifetimes and spatial scales of emission network cells in the solar chromosphere were studied from a nearly continuous sequence of Caii K filtergrams, obtained from Antarctica. The temporal autocorrelation function ...
  • Daily Variation of Tilt Angles of Sunspot Groups 
    Muneer, S; Singh, J (Astronomical Society of India, 2003)
    The influence of polarity separation on the daily tilt angle variation of sunspot groups has been studied from a selected number of observations of the Sun spanning the entire 22nd solar cycle. Daily white-light images of ...
  • Data pipeline architecture and development for VELC onboard Space Solar Mission AdityaL1 
    Singh, J; Prasad, B. R; Sumana, Chavali; Amit Kumar; Varun Kumar; Priyal, Muthu; Venkata Suresh, Narra (Elsevier Ltd., 2022-03-15)
    ADITYA L-1 is India’s first dedicated mission to study Sun and its atmosphere with Visible Emission Line Coronagraph (VELC), a major payload on ADITYA-L1. VELC has provision to make imaging and spectroscopic observations ...
  • The Dependence of Chromospheric CA II K Network Cell Sizes on Solar Latitude 
    Raju, K. P; Srikanth, R; Singh, J (Springer, 1998-06)
    Calcium K line spectroheliograms obtained during the solar minimum phases at Kodaikanal between 1913–1974 have been used to study the network cell sizes. The autocorrelation is calculated for two-dimensional strips at 5° ...
  • Dependence of Supergranular Length-Scales on Network Magnetic Fields 
    Raju, K. P; Singh, J (Springer, 2002-05)
    In an earlier paper by Raju, Srikanth, and Singh (1998), the average size of chromospheric network cells has been shown to have a dependence on the solar latitude. This was presumed to be due to the reduction of supergranular ...
  • A dependence on solar cycle of the size of the Ca/+/ network 
    Singh, J; Bappu, M. K. V (Springer, 1981-05)
    Calcium network diameters are shown to be smaller by 5% at solar maximum than at minimum. The average cell size at minimum is 22,115 + or - 99 km. The average size at solar maximum is 20,920 + or - 112 km, though individual ...
  • Detection of cooler loop-tops in a coronal structure 
    Singh, J; Sakurai, T; Ichimoto, K (Anita Publications, 2004-12)
    We have obtained off the limb' spectroscopic observations covering a coronal region of 200" x 500" in [Fe x] 6374 A and [Fe xi) 7892 A emission lines simultaneously. Yohkoh soft X-ray images of the sun showed two independent ...

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