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Browsing Kodaikanal Observatory Publications by Issue Date

Browsing Kodaikanal Observatory Publications by Issue Date

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  • Why is geomagnetic activity during the ending years of a solar cycle well correlated to the maximum of the next cycle? 
    Gokhale, M. H (Indian Institute of Astrophysics, 1979-11)
    The two component nature of the solar activity cycle as resulting from the shock-transition model of the solar magnetic cycle, provides for a correlation between a measure of coronal hole formations during the ending years ...
  • Solution of radiative transfer equation in spherically symmetric media with spherical harmonic approximation 
    Peraiah, A (Indian Institute of Astrophysics, 1979-11)
    A numerical method for obtaining solution of radiative transfer equation in spherically symmetric media with spherical harmonic approximation is presented. The angle derivative is approximated by an orthonormal polynomial ...
  • Isodensitometry of Omega Centauri and 47 Tucanae 
    Scaria, K. K (Indian Institute of Astrophysics, Bangalore, 1980)
    We present details of procedure on equidensitometry of globular clusters using the Sabattier technique in photography. Equidensitometry of Omega Centauri and 47 Tuc shows that both clusters become more elliptical beyond r ...
  • Lines Formed in Slowly Expanding Thin Spherical Shell 
    Peraiah, A; Raghunath, G; Nagendra, K. N (Indian Institute of Astrophysics, Bangalore, 1980)
    We have investigated how an optically thin spherical shell with small velocities change the profiles and equivalent widths of the lines. We have employed several types of variations in density, velocity of expansion and ...
  • A Simple Digital System Drive for Small Telescopes 
    Bhattacharyya, J. C; Ramamoorthy, K. S; Chandramohan, R (Indian Institute of Astrophysics, Bangalore, 1980)
    A variable stable frequency source employing a crystal oscillator and a programmable digital divider chain is described. The system offers an ideal arrangement for controlling tracking rates of small and medium size ...
  • Rotational Effects on line Source Function 
    Peraiah, A; Raghunath, G (Indian Institute of Astrophysics, Bangalore, 1980)
    The effects of rotation are investigated on the source functions in an expanding atmosphere. We have considered a non-LTE two-level atom in an extended atmosphere. We have also made use of von Zeipel`s theorem in giving ...
  • Simultaneous Solution of Radiative Transfer Equation in the Comoving Frame and the Statistical Equilibrium Equation with Complete Redisribution 
    Peraiah, A (Indian Institute of Astrophysics, Bangalore, 1980)
    Complete redistribution with Voigt profile function has been employed in obtaining the simultaneous solution of line transfer and the statistical equilibrium equation for a non-LTE two level atom in an extended stellar ...
  • Photometry of Zeta Aurigae during the 1977 and 1979-80 Eclipses 
    Mohin, S; Raveendran, A. V; Mekkaden, M. V (Indian Institute of Astrophysics, Bangalore, 1980)
    UBV photometry of Zeta Aurigae during the 1977 and 1979-80 eclipses is presented. From an analysis of the available photometry, it is concluded that the long term intrinsic variation in the brightness of the late-type super ...
  • Flow of Gas along a Magnetic field with Time-Dependent Geometry 
    Hasan, S. S; Venkatakrishnan, P (Indian Institute of Astrophysics, Bangalore, 1980)
    The flow of gas along a magnetic field with time dependent geometry has been studied. It is seen that the velocity of the flow in the direction of the magnetic field depends both on the magnitude of the velocity of flow ...
  • Fluxvector Splitting of the Inviscid Radiation Gas Dynamic Equations 
    Peraiah, A (Indian Institute of Astrophysics, Bangalore, 1980)
    We have analysed various schemes for the iterative simultaneous solution of the inviscid gas dynamic equations. We have considered the problem from the point of view of the stellar atmospheres. The difference between ...
  • Automated Microdensitometer 
    Viswanath, C (Indian Institute of Astrophysics, Bangalore, 1980)
    An interface to a Carl Zeiss microdensitometer and the HCL's micro-computer MICRO 2200 has been built to digitize, log, and process the analog variable density information on photographic plates. The automated process ...
  • 1.5M Aluminizing Plant of the Indian Institute of Astrophysics 
    Saxena, A. K; Jayarajan, A. P; Kumar, K (Indian Institute of Astrophysics, Bangalore, 1980)
    The design and features of 1.5m vacuum coating plant an in house facility at the Kavalur Observatory for periodic aluminizing of astronomical optics are described. A typical performance data is given.
  • Transient Solution of Equations of Hydrodynamics in Gas Clouds 
    Peraiah, A (Indian Institute of Astrophysics, 1981)
    We have presented numerical results of transient phenomenon in incompressible fluids. This has been obtained by solving the equations of conservation of momentum, energy and mass in X and Y geometry. We have used the explict ...
  • Effects of Velocities on Ca II H and K Lines 
    Rangarajan, K. E; Mohan Rao, D; Peraiah, A (Indian Institute of Astrophysics, Bangalore, 1981)
    Ca II H and K (3968, 3933) and infrared triplet lines lamda lamda lamda 8498, 8662, 8542 were calculated in a very slowly expanding medium. Five level atom with continuum was considered. Radiative transfer equation and ...
  • Formation of Spectral Lines with the Redistribution Function R1 along the line of Sight 
    Peraiah, A (Indian Institute of Astrophysics, Bangalore, 1981)
    We studied the formation of spectral lines at infinity with the redistribution function R1. The radial optical depths considered are 5, 5, 10, 50 and 100. A linear law of velocity is assumed in these calculations. Profiles ...
  • Numerical Evaluation of Spherical Bessel and Related Functions 
    Shah, G. A (Indian Institute of Astrophysics, Bangalore, 1983)
    Techniques for calculating the spherical Bessel functions of complex argument lying in any quadrant of the z-plane and arbitary orders have been developed. The method applies to real, pure imaginary or complex arguments. ...
  • Limb Darkening due to the Incidence of a Parallel Beam of Radiation 
    Peraiah, A (Indian Institute of Astrophysics, Bangalore, 1983)
    We have investigated how the radiation is distributed from the centre to the limb when the atmosphere receives a parallel beam of radiation from infinity. We have considered a purely reflecting surface at the bottom of the ...
  • The Absolute Magnitudes of Wolf-Rayet Stars HD 151932 and HD 152270 
    Shylaja, B. S; Bappu, M. K. V (Indian Institute of Astrophysics, Bangalore, 1983)
    The absolute visual magnitudes of two Wolf-Rayet stars HD 151932 (WN 7) and HD 152270 (WC 7+08) have been determined from their energy distributions and monochromatic magnitudes least contaminated by emission lines taking ...
  • The Rotation of the Sun from Mount Wilson Sunspot Mesurements 
    Howard, Robert; Gilman, Peter (Indian Institute of Astrophysics, Bangalore, 1984)
  • Line Asymmetry and Magnetic Fields 
    Livingston, William (Indian Institute of Astrophysics, Bangalore, 1984)
    The measurement of the asymmetries of Fraunhofer lines shows promise as a diagnostic of convection at the surface layers of the Sun and Stars. We discuss today the observational evidence that the asymmetry, and by inference ...

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