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  • Optical Variability of Blazars 
    Ghosh, K. K; Ramsey, B. D; Sadun, A. C; Soundararajaperumal, S (The American Astronomical Society, 2000-03)
    In this paper we show the results of our monitoring the flux variability of 15 blazars, within the redshift range of 0.07-2.06, all with a visual magnitude range between 14 and 20 mag. Because blazars have displayed ...
  • Optical variability of narrow-line and broad-line Seyfert 1 galaxies 
    Rakshit, S; Stalin, C. S (IOP Publishing, 2017-05)
    We studied the optical variability ( OV ) of a large sample of narrow-line Seyfert 1 ( NLSy1 ) and broad-line Seyfert 1 ( BLSy1 ) galaxies with z  <  0.8 to investigate any differences in their OV ...
  • Optical variability of radio-intermediate quasars 
    Goyal, Arti; Gopal-Krishna; Joshi, S; Sagar, R; Wiita, Paul J; Anupama, G. C; Sahu, D. K (Blackwell Publishing, 2010-02)
    We report the results of our intensive intranight optical monitoring of eight optically bright `radio-intermediate quasars' (RIQs) having flat or inverted radio spectra. The monitoring was carried out in R band on 25 nights ...
  • An Optical, Dual-Beam, Automated Medium Resolution Spectropolarimeter for the Vainu Bappu Telescope 
    Chakraborty, P; Vasundhara, R (Springer, 2003-03)
    Fabrication of an optical dual-beam spectropolarimeter as an add-on facility to an existing astronomical spectrograph at the Vainu Bappu Telescope is described. The polarimetric optics consists of a superachromatic ...
  • The optical-GeV connection in fermi blazars 
    Bhoomika (Indian Institute of Astrophysics, 2020-07)
    Blazars are a class of active galactic nuclei (AGN) that have relativistic jets that are oriented close to the observers line of sight. They display ux variability across the en- tire accessible electromagnetic spectrum ...
  • Optical/IR studies of Be stars in NGC 6834 with emphasis on two specific stars 
    Mathew, B; Varricatt, W. P; Subramaniam, A; Ashok, N. M; Banerjee, D. P. K (IOP Publishing, 2014-09)
  • Optimization of existing centroiding algorithms for Shack Hartmann sensor 
    Vyas, A; Roopashree, M. B; Prasad, B. R (2009)
    Three centroiding techniques to estimate the position of the spots in a Shack Hartmann sensor: Normalized Centre of Gravity (CoG), Iteratively Weighted Centre of Gravity (IWCoG) and Intensity Weighted (IWC) centroiding are ...
  • Optimizing the modal index of Zernike polynomials for regulated phase screen simulation 
    Vyas, A; Roopashree, M. B; Prasad, B. R (SPIE--The International Society for Optical Engineering, 2010-07)
    Simulations of optical wavefronts propagating through the atmosphere are widely used in the design and testing of adaptive optics systems. Phase screens are defined by their spatial and temporal statistics. In many ...
  • Optimum design and development of segmented mirror telescope optics and phasing system 
    Jacob, A (Indian Institute of Astrophysics, 2020-10)
    Astronomy today is in the path of constructing large telescopes. Due to several manufacturing and maintenance difficulties, large telescopes of more than 8 m are predominantly segmented. To fulfill the need for its growing ...
  • Optimum image parameter ranges for TACTIC imaging elements : guidance from simulations 
    Koul, M. K; Charagi, S. K; Rannot, R. C; Sapru, M. L; Bhat, C. L (Astronomical Society of India, 2002)
    In this paper, we present some results on the performance characteristics of the TACTIC Imaging Element (IE) as predicted by extensive simulation studies. The main features studied are the optimum image parameter ranges ...
  • Opto-mechanical assembly and ground calibration of LUCI 
    Mathew, J; Nair, B. G; Sriram, S; Kamath, P. U; Prakash, A; Mayuresh, Sarpotdar; Ambily, S; Nirmal, K; Sreejith, A. G; Safonova, M; Murthy, J; Brosch, N (SPIE--The International Society for Optical Engineering, 2018-08-20)
    The Lunar Ultraviolet Cosmic Imager (LUCI) is an innovative all-spherical mirrors telescope, proposed to fly as a scientific UV imaging payload on a lunar mission in collaboration with Indian Aerospace Company-TeamIndus, ...
  • Opto-thermal analysis of a lightweighted mirror for solar telescope 
    Banyal, R. K; Ravindra, B; Chatterjee, S (Optical Society of America, 2013-03-25)
    In this paper, an opto-thermal analysis of a moderately heated lightweighted solar telescope mirror is carried out using 3D finite element analysis (FEA). A physically realistic heat transfer model is developed to account ...
  • Orbit of Eros, its next opposition on april 19th, 1917 
    Ridsdale, A. C (Astronomical Society of India, 1917)
  • Orbit of the spectroscopic binary B Persei 
    Rajamohan, R; Parthasarathy, M (Indian Academy of Sciences, 1975-04)
    Spectroscopic orbital elements are derived for the close binary system b Persei on the basis of forty spectrograms. The period is redetermined as 1.527360 days, and variations in the orbital elements are confirmed by ...
  • Orbital decay of protostellar binaries in molecular clouds 
    Gorti, U; Bhatt, H. C (Royal Astronomical Society, 1996-11)
    The evolution of protostellar binary system is investigated while it is embedded in its parent molecular cloud core and is acted upon by gas drag as a result of dynamical friction. Approximate analytical results are obtained ...
  • Orbital Evolution of the Binary X-ray Pulsar Her X-1 
    Bhatt, N; Paul, B; Koul, C. L (Astronomical Society of India, 2003)
    We report the discovery of a break in the orbital period evolution of Her X-1, coincident with a recent anomalous low state.
  • Orbital period modulation and spot activity in the RS CVn binary V711 Tauri 
    Muneer, S; Jayakumar, K; Rosario, M. J; Raveendran, A. V; Mekkaden, M. V (EDP Sciences, 2010-10)
    We attempt to establish the real nature of the orbital period variation and its relation to the spot activity of V711 Tau, and determine why the (B–V) colour of the star appears to be nearly independent of its V magnitude. ...
  • Orbital signatures from observed light curves of blazars 
    Mangalam, A; Mohan, Prashanth (Indian Academy of Sciences, 2014-04)
    Variability in active galactic nuclei is observed in ultraviolet to X-ray emission based light curves. This could be attributed to orbital signatures of the plasma that constitutes the accretion flow on the putative disk ...
  • Orbital solutions derived from radial velocities and time delays for four Kepler systems with A/F-type (candidate) hybrid pulsators⋆ 
    Lampens, P; Vermeylen, L; Fremat, Y; Sodor, A; Skarka, M; Samadi-Ghadim, A; Bognar, Zs; Lehmann, H; De Cat, P; Goswami, A; Dumortier, L (EDP Sciences, 2021-03)
    Context. The presence of A/F-type Kepler hybrid stars extending across the entirety of the δ Scuti – γ Doradus instability strips and beyond remains largely unexplained. In order to better understand these particular stars, ...
  • Orbits of double stars 
    Jacob, W. S (Royal Astronomical Society, 1847-01)

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