Browsing by Author "Gupta, S. S"

CA II K Line Profile of the Truly Quiet Sun

Sivaraman, K. R; Gupta, S. S; Kariyappa, R (Kluwer Academic Publishers, 1996-01)

While evaluating the chromospheric variability (solar cycle related or any other) using the Ca II K line (λ3933.684 Å) as an indicator, an essential prerequisite is the knowledge of the profile of a truly quiet Sun in the ...

Calibration on the Sun for stellar magnetic fields

Sivaraman, K. R; Bagare, S. P; Gupta, S. S; Kariyappa, R (Springer, 1987-07)

The intimate association between the surface magnetic fields and the Ca II K-line emission known to exist on the Sun, holds a promise for using this property to detect the presence of global magnetic fields on Sun-like ...

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 ...

Effect of the M 9.3 Sumatra-Andaman islands earthquake of 26 December 2004 at several permanent and campaign GPS stations in the Indian continent

Jade, S; Vijayan, M. S. M; Gupta, S. S; Kumar, P. D; Gaur, V. K; Arumugam, S (Taylor and Francis Ltd, 2007-07)

The effect of the 26 December 2004 Sumatra-Andaman earthquake on the Indian continent has been estimated from the analysis of GPS data from permanent and campaign GPS sites in the Indian continent. Co-Seismic displacements ...

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 ...

Estimates of interseismic deformation in Northeast India from GPS measurements

Jade, S; Mukul, M; Bhattacharyya, A. K; Vijayan, M. S. M; Jaganathan, S; Ashok Kumar; Tiwari, R. P; Arun Kumar; Kalita, S; Sahu, S. C; Krishna, A. P; Gupta, S. S; Murthy, M. V. R. L; Gaur, V. K (Elsevier B.V, 2007-11)

Estimates of interseismic deformation in northeastern India based on GPS measurements at eight permanent stations (2003–2006) and six campaign sites (1997–2006) are presented here. The Euler pole of rotation of Indian ...

Evidence for return meridional flows in the convection zone

Sivaraman, K. R; Sivaraman, H; Gupta, S. S; Howard, R. F (Springer, 2010)

We report velocities of meridional motions derived from the latitude drifts of spot groups measured on photographic images of the Sun in the Kodaikanal observatory archives. They serve to measure different meridional flows ...

Filament activity in a quiet region flare

Sundararaman, K; Gupta, S. S; Selvendran, R (Indian Academy of Sciences, 1993-03)

We have taken the case of a circular H-alpha filament observed on May 9, 1979 erupting into a double-ribbon flare associated with a nonspot region. The plage motions are responsible for the filament reorientation and, here ...

High Resolution Multislit Spectroscopy of Solar Corona in two lines during the Total Solar Eclipse of Oct. 24, 1995

Singh, J; Gupta, S. S; Cowsik, R (Indian Institute of Astrophysics, Bangalore, 1997)

Two coronal emission lines 5303 Armstrong (Fe XIV) and 6374 Armstrong (Fe X) corresponding to ionization temperatuess of 2 and 1 million degree kelvin respectively were used to obtain the high resolution coronal spectra ...

Measurement of Kodaikanal White-Light Images - II. Rotation Comparison and Merging with Mount Wilson Data

Howard, R. F; Gupta, S. S; Sivaraman, K. R (Kluwer Academic Publishers, 1999-05)

Sunspot umbral positions and areas were measured for 82years (1906-1987) of daily, full-disk photoheliogram observations at the Kodaikanal station of the Indian Institute of Astrophysics. The measurement technique and ...

Measurement of Kodaikanal White-Light Images - III. Rotation Rates and Activity Cycle Variations

Gupta, S. S; Sivaraman, K. R; Howard, R. F (Kluwer Academic Publishers, 1999-09)

The Kodaikanal sunspot data set covering the interval 1906-1987 is analyzed for differential rotation of sunspots of different sizes. As is known, smaller sunspots rotate faster than larger sunspots, and this result is ...

Measurement of Kodaikanal white-light images - IV. Axial Tilt Angles of Sunspot Groups

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 ...

Measurement of Kodaikanal white-light images - VI. Variation of Rotation Rate with Age of Sunspot Groups

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 ...

Measurement of kodaikanal white-light images – V. Tilt-angle and size variations of sunspot groups

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 ...

Measurement of Kodaikanal white-light images. I - A comparison of 35 years of Kodaikanal and Mount Wilson sunspot data

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 ...

Measurement of Kodaikanal White-Light Images: Relaxation of Tilts of Spot Groups as Indicator of Subsurface Dynamics of Parent Flux Loops

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 ...

On the eruption of prominences and disappearance of quiescent filaments

Singh, J; Gupta, S. S (Springer, 1995-05)

We suggest the following heuristic model for the evolution of a quiescent filament. The middle part of the filament rises due to heating, while its ends remain anchored in the chromosphere; and a kink appears in the H alpha ...

On the relation between magnetic field strength and Wilson depression in sunspots

Bagare, S. P; Gupta, S. S (Astronomical Society of India, 1998)

At the Solar Tower Telescope of Kodaikanal Observatory, we obtained Zeeman spectra of sunspots on their disk passage during 1979-84 (Solar max. 21). Using this data and full disk white light pictures obtained at the ...

Results from a revisit to the K2V bright points

Sivaraman, K. R; Gupta, S. S; Livingston, W. C; Damé, L; Kalkofen, W; Keller, C. U; Smartt, R; Hasan, S. S (European Southern Observatory, 2000-11)

We have used pairs of temporally simultaneous CaII K-line spectroheliograms and magnetic area scans to search for spatial correlation between the CaII K2V bright points in the interior of the network and corresponding ...

Return Meridional Flow in the Convection Zone from Latitudinal Motions of Umbrae of Sunspot Groups

Sivaraman, K. R; Sivaraman, H; Gupta, S. S; Howard, R. F (Springer, 2010-10)

We have derived the velocities of meridional flows by measuring the latitudinal motions (or drifts) of umbrae of spot groups classified into three categories of area: 0 – 5 μ, 5 – 10 μ, and >10 μ (μ area in millionths of ...

Browsing by Author "Gupta, S. S"

Browsing by Author "Gupta, S. S"

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