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  • Performance analysis of free space optical communication in open-atmospheric turbulence conditions with beam wandering compensation control 
    Anthonisamy, Arockia Bazil Raj; Durairaj, Padmavathi; Lancelot, J. P (IET, 2016-06-16)
    Among various atmospheric effects, beam wandering is the main cause for the major power loss in free space optical communication (FSOC) which cannot be resolved without incorporating the beam wandering compensation (BWC) ...
  • Performance Evaluation of Adaptive Optics Systems 
    Sridharan, R; Raja Bayanna, A; Srivastava, N; Kumar, B; Ravindra, B; Gupta, S. K; Jain, N; Ambastha, A; Venkatakrishnan, P (Astronomical Society of India, 2003)
    Adaptive Optics (AO) systems improve the resolution of ground based telescopes and allow for long exposure images. Their performance depends on the seeing conditions at the time of observations. In this paper, we evaluate ...
  • Performance evaluation of high-speed camera system for adaptive optics 
    Chinnappan, V; Saxena, A. K; Sreenivasan, A (Astronomical Society of India, 2002-09)
    Atmospheric turbulence distorts the incoming wavefront from the star light, thus severely limiting the resolution of the groundbased optical telescopes (Fried 1966). Adaptive optics is being implemented in all big ...
  • Performance of 10.5μm quantum well infrared photodetector for astronomical applications 
    Joseph, Celine; Saxena, A. K (Department of Applied Optics and Photonics, University of Calcutta, 2011)
  • Performance of a speckle interferometer 
    Saha, S. K; Jayarajan, A. P; Sudheendra, G; Chandra, A. U (Astronomical Society of India, 1997)
    An interferometer system for use at the 2.34 meter Vainu Bappu Telescope (VBT), situated at Vainu Bappu Observatory (VBO), Kavalur, to obtain speckle-grams of astronomical objects in the visible wavelength, has been ...
  • Performance of centroiding algorithms at low light level conditions in adaptive optics 
    Vyas, A; Roopashree, M. B; Prasad, B. R (The Institute of Electrical and Electronics Engineers, Inc, 2009)
    The performance metrics of different centroiding algorithms at low light level conditions were optimized in the case of a Shack Hartmann Sensor (SHS) for efficient performance of the adaptive optics system. For short ...
  • Performance of the IIA mosaic CCD camera system 
    Naidu, B. N; Srinivasan, R; Mohan, V; Sagar, R (Astronomical Society of India, 2001)
    We evaluate performance of the 4K x 4K mosaic CCD camera system developed at the Indian Institute of Astrophysics using four Thomson CCDs in a buttable configuration. The camera system consists of a mosaic CCD dewar developed ...
  • Performance of the low light level CCD camera for speckle imagmg 
    Saha, S. K; Chinnappan, V (Astronomical Society of India, 2002-09)
    A new generation CCD detector caJ.led low light level OOD (L3CCD) that performs like an intensified CCD without incorporating a micro channel plate (MOP) for light amplification was procured and tested. A series of ...
  • Performance of the UVIT Level-2 pipeline 
    Ghosh, S. K; Tandon, S. N; Joseph, P; Devaraj, A; Shelat, D. S; Stalin, C. S (Indian Academy of Sciences, 2021-10)
    Performance of the Level-2 pipeline, which translates the UVIT data created by the ISRO’s ground segment processing systems (Level-1) into astronomer ready scientific data products, is described. This pipeline has evolved ...
  • Performance results of HESP physical model 
    Anantha, Ch; Sivarani, T; Jones, D; Giridhar, S; Grobler, D; Jakobsson, R (2017-02)
    As a continuation to the published work on model based calibration technique with HESP(Hanle Echelle Spectrograph) as a case study, in this paper we present the performance results of the technique. We also describe how ...
  • Performance studies of the PACT experiment 
    Vishwanath, P. R; Acharya, B. S; Bhat, P. N; Chitnis, V. R; Majumdar, P; Rahman, M. A; Singh, B. B (Astronomical Society of India, 2002)
    Monte Carlo calculations have been done to understand various characteristics like the energy threshold, collection area etc of the recently commissioned PACT. The energy threshold of the array for gamma rays is found to ...
  • Period changes in the RR Lyrae stars of NGC 6171 (M107) 
    Arellano Ferro, A; Rosenzweig, P; Luna, A; Deras, D; Muneer, S; Giridhar, S; Michel, R (WILEY-VCH Verlag GmbH & Co., 2018-02)
    Based on photometric data obtained between 1935 and 2017, O −C diagrams were built for 22 RR Lyrae stars in the globular cluster NGC 6171, leading to the discovery of secular period changes in four variables for which we ...
  • Period study of the Algol-type eclipsing binary - R Canis Majoris 
    Radhakrishnan, K. R; Abhyankar, K. D; Sarma, M. B. K (Astronomical Society of India, 1984-06)
    Photoelectric observations of the Algol-type eclipsing binary R Canis Majoris during three consequtive observing seasons of 1979-82 gave a total of ten primary minima in each of the V and B passbands and nine in the U ...
  • Period study of the RS CVn eclipsing binary SV Camelopardalis 
    Sarma, C. V. S. R; Sarma, M. B. K; Abhyankar, K. D (Astronomical Society of India, 1985-12)
    Using the available photographic and photoelectric times of minima, we have revised the elements of the light-time orbit of SV Camelopaedalis, an RS CVn type eclpsing binary. Taking a mass function of 0.118 M and the ...
  • Period study of the short period RS CVn type eclipsing binary UV Piscium 
    Vivekananda Rao, P; Sarma, M. B. K (Astronomical Society of India, 1983-03)
    The short period RS CVn type eclipsing binary UV Piscium was observed photoelectrically with standard U, B, V filters for three consecutive observing seasons during 1976-1979. A total of nine primary minima in each of V ...
  • Period-brightness relationship in chromospheric bright points 
    Kariyappa, R; Satya Narayanan, A; Dame, L (Astronomical Society of India, 2005-03)
    Chromospheric bright points are sites where intense heating takes place by 3-min period waves. A 35-min-long time series of photographic spectra obtained in CaII H-line on a quiet region at the center of the solar disk ...
  • Periodic activity in the T Tauri star TW Hya 
    Mekkaden, M. V (Astronomical Society of India, 1990)
    UBVRI photometry of the isolated T Tauri star TW Hya, obtained during 1987 April from ESO, is presented. The data analysis shows a periodicity of 2.195 d in light variation. The steep increase of amplitude towards shorter ...
  • Periodic and Quasi-Periodic Variations in the Ca K Index During the 20th Century Using Kodaikanal Data 
    Priyal, Muthu; Singh, J; Ravindra, B; Chandar Shekar, B (Springer, 2019-09)
    We have digitized the Ca K images obtained at Kodaikanal Observatory with a pixel resolution of 0.86 arcsec and 16-bit readout to achieve better spatial and photometric accuracy. In addition to the general photometric ...
  • Periodic modulations in the optical light curves of EX Hydrae 
    Seetha, S; Sharma, D. P; Padmini, V. N; Marar, T. M. K; Kasturirangan, K (Kluwer Academic Publishers, 1987-02)
    The authors present here new results on the periodic modulations in the optical light curves of EX Hydrae observed during 1982 - 84. The period analysis has been done using synchronous summation and discrete Fourier transform ...
  • Periodicities in the North–South Asymmetry of the Solar Differential Rotation and Surface Magnetic Field 
    Javaraiah, J; Gokhale, M. H (Springer, 1997-02)
    We have studied the temporal variations in the north–south asymmetries of the differential rotation parameters A, B, and the mean rotation rate , by determining their values from Greenwich data for sunspot groups ...

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