IIA Institutional Repository

Browsing by Author "Singh, J"

Browsing by Author "Singh, J"

Sort by: Order: Results:

  • 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 ...
  • Detection of high-frequency oscillations and damping from multi-slit spectroscopic observations of the corona 
    Samanta, T; Singh, J; Sindhuja, G; Banerjee, D (Springer, 2016-01)
    During the total solar eclipse of 11 July 2010, multi-slit spectroscopic observations of the solar corona were performed from Easter Island, Chile. To search for highfrequency waves, observations were taken at a high cadence ...
  • Detection of Short-Period Coronal Oscillations during the Total Solar Eclipse of 24 October, 1995 
    Singh, J; Cowsik, R; Raveendran, A. V; Bagare, S. P; Saxena, A. K; Sundararaman, K; Krishan, V; Naidu, N; Samson, J. P. A; Gabriel, F (Springer, 1997-02)
    An experiment to search for short-period oscillations in the solar corona was conducted during the total solar eclipse of 1995 October 24 at Kalpi, India. The intensity in the continuum, centred around 5500 Å and with a ...
  • Determination of the choromospheric quiet network element area index and its variation during 2008 and 2011 
    Singh, J; Ravindra, B; Selvendran, R; Kumaravel, P; Priyal, M; Priya, T. G; Amareswari, K (Chinese Academy of Sciences, 2012-02)
    Generally it has been considered that the plages and sunspots are the main contributors to the solar irradiance. There are small scale structures on the sun with intermediate magnetic fields that could also contribute ...
  • Determining the variations of Ca–K index and features using century-long equal-contrast images from Kodaikanal observatory 
    Singh, J; Priyal, M; Ravindra, B (IOP Publishing, 2021-02-20)
    In an earlier analysis of Ca–K spectroheliograms obtained at the Kodaikanal Observatory, the "Good" images were used to investigate variations in the chromosphere. However, the contrast of the images varied on a day-to-day ...
  • 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 ...
  • Digitization of Kodaikanal Data 
    Singh, J; Muneer, S; Bagare, S. P; Rangarajan, K. E; Ramesh, K. B; Varghese, B. A; Samson, J. P. A; Devendran, P; Hariharan, G (Astronomical Society of India, 2003)
    In this report we describe a digitizer developed in the laboratories of the Indian Institutes of Astrophysics (IIA) to digitize the large amount of solar synoptic data obtained since 1904 at Kodaikanal. We show a sample ...
  • Distribution of Supergranular Sizes 
    Srikanth, R; Singh, J; Raju, K. P (The American Astronomical Society, 2000-05)
    A gradient-based method of tessellation was applied to SOHO Dopplergrams and to Ca II K filtergrams in order to study the cellular pattern of the solar surface, in specific the geometric relationship between the tessellation ...
  • The Distribution of the Quiet Sun Photospheric Magnetic Flux 
    Srikanth, R; Singh, J; Bagare, S. P (Astronomical Society of India, 2002-12)
    A gradient-based tessellating algorithm is used to study the magnetic field structure of the quiet Sun photosphere using SoRO full disk magnetograms. We find that the field is not uniformly distributed, but parcelled ...
  • Do the Line Widths of Coronal Emission Lines Increase with Height above the Limb? 
    Singh, J; Sakurai, T; Ichimoto, K (University of Chicago Press, 2006-03)
    In our earlier studies we obtained off-the-limb spectroscopic observations in a number of forbidden emission lines ([Fe X–XIV]) to study the physical properties and their temporal variations in steady coronal structures. ...
  • Eclipse observations of coronal emission lines. I.[FeX]6374 A profiles at the eclipse of 16 February 1980 
    Singh, J; Bappu, M. K. V; Saxena, A. K (Indian Academy of Sciences, 1982-09)
    Coronal spectra during the total solar eclipse of February 16, 1980, obtained in the 6374 A (forbidden Fe X) line using a multislit spectrograph are discussed. The dispersion of these spectra is 2.5 A/mm. The observed line ...
  • Effects of magnetic shear, spot, and plage rotation on prominence evolution 
    Rausaria, R. R; Gupta, S. S; Selvendran, R; Raman, K. S; Singh, J (Kluwer Academic Publishers, 1993-08)
    We have studied the evolution of two dark H-alpha filaments as prominences during their disk passage from February 12 to February 19, 1992 and from March 6 to March 17, 1992, using Kodaikanal Observatory H-alpha and Ca II ...
  • Emission lines of inner corona observed during the total solar eclipse of 1980 February 16 
    Singh, J; Rajamohan, R; Raheem, K. C. A (Astronomical Society of India, 1983-12)
    Spectrograms of the inner solar corona were obtained during the 1980 total solar eclipse. Two Ebert-Fastie type spectrographs with circular slits were used to obtain spectra on the east and the west at 1.06 R. These ...

Search DSpace

Browse

My Account