Sivaraman, K. R; Gupta, S. S; Howard, R. F(Kluwer Academic Publishers, 1999-10)
The Kodaikanal sunspot data set, covering the interval 1906-1987, is used in conjunction with the similar Mount Wilson sunspot data set, covering the interval 1917-1985, to examine characteristics of sunspot group axial ...
Sivaraman, K. R; Sivaraman, H; Gupta, S. S; Howard, R. F(Springer, 2003-05)
We find from an analysis of the Kodaikanal sunspot group data that the rotation rates of spot groups increase with their age when the rotation rates are computed after sorting the spot groups life-span-wise. We confirm ...
Howard, R. F; Sivaraman, K. R; Gupta, S. S(Springer, 2000-10)
We examine here the variations of tilt angle and polarity separation (as defined in this paper) of multi-spot sunspot groups from the Kodaikanal and Mount Wilson data sets covering many decades. We confirm the tilt-angle ...
Sivaraman, K. R; Gupta, S. S; Howard, R. F(Kluwer Academic Publishers, 1993-07)
Areas and positions of individual sunspot umbrae measured in white-light solar images from Kodaikanal and Mount Wilson are compared and shown to be in quite good agreement. The agreement is sufficiently good that it is ...
Sivaraman, K. R; Gokhale, M. H; Sivaraman, H; Gupta, S. S; Howard, R. F(The American Astronomical Society, 2007-03)
We reexamine the evolution of the observed tilts θ of spot groups with life spans 2–7 days in the two latitude belts <13° and >13°. Using an iterative procedure, we refine the linear fit between θ and the daily tilt angle ...
Makarov, V. I; Stoianova, M. N; Sivaraman, K. R(Indian Academy of Sciences, 1982-12)
The results of a study of the morphology of the large-scale filament structures of the sun and their relations with the distribution of the large-scale magnetic field on the solar surface are reported. A continuous filament ...
Babu, G. S. D; Nathan, J. S; Rajamohan, R; Sivaraman, K. R(Astronomical Society of Indian, 1989-09)
IHW filter photometry of Comet Halley was carried out on seven nights during pre-perihelion period and on six nights during post-perihelion period, using the 40-cm telescope at the Vainu Bappu Observatory, Kavalur, as a ...
The poleward migration-trajectory diagram of filament bands is derived for the years 1915-1982 from the H-alpha synoptic charts. The global solar activity commences soon after the polar-field reversal in the form of two ...
Iijima, T; Gehrz, R. D; Jones, T. J; Lawrence, G; Sivaraman, K. R; Prabhu, T. P; Ghosh, K. K; Anupama, G. C; Selvakumar, G(Smithsonian Astrophysical Observatory, 1991-04)
Sivaraman, K. R(D. Reidel Publishing Co., 1973-12)
The 5-min oscillations in the photospheric velocity fields have been studied in detail from measurements on 14 absorption lines from three time sequences of spectrograms of high quality. The lines cover a range of heights ...
The coherence and phase spectra between velocity oscillations in different pairs of lines have been studied. The oscillation in the high level lines are found to lag behind those in the low level lines in general. There ...
Singh, J; Sivaraman, K. R; Rajamohan, R(Indian Institute of Astrophysics, Bangalore, 1988)
During the total solar eclipse of 1983 June 11, coronal spectra were obtained in the 5303A (Fe XIV) line using the multislit spectrograph at a dispersion of 2.17A mm-1 . The line profiles measured at 113 locations from ...
Bappu, M. K. V; Bhattacharyya, J. C; Sivaraman, K. R(D. Reidel Publishing, 1972-10)
Emission lines of the Balmer series, D3 and H and K are reported present on a coronal spectrogram obtained at the March 7, 1970 eclipse. Arguments are presented to show that these could not have originated from scattering ...
Makarov, V. I; Sivaraman, K. R(Astronomical Society of Indian, 1986-09)
The H-alpha synoptic charts for the 1904-1982 period and data on the polar prominences for the 1870-1905 period are used to investigate the polarity reversal of the polar magnetic field on the sun for 11 solar cycles. Good ...
Krishan, V; Sivaraman, K. R(D. Reidel Publishing Co., 1982-04)
Direct photographs of Comet Ikeya-Seki obtained on four consecutive days from October 29 to November 1, 1965, are used for an analysis of the multiple helical structures in the ionised tail. The formation of these structures ...