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  • Optical Studies of V4332 Sagittarii: Detection of Unusually Strong K I and Na I Lines in Emission 
    Banerjee, D. P. K; Ashok, N. M (University of Chicago Press, 2004)
    We present optical observations of the enigmatic nova-like variable V4332 Sgr. The importance of this object should not be understated since it is considered to be the possible prototype of a new class of eruptive variables. ...
  • Optical telescopes in India 
    Bhattacharyya, J. C (National Institute of Science Communication and Information Resources, 1989-08)
    Fabrication and use of optical telescopes for astronomical observations in India have been reviewed. Evolution of telescopes, their optics, mounting and drive system leading to large aperture instruments of today has been ...
  • Optical testing of a gamma-ray telescope mirror 
    Udupa, D. V; Shukla, R. P; Saksena, G. D (Astronomical Society of India, 1993)
    A large size concave mirror for use in the gamma-ray telescope TACTIC was tested. Focal length of the concave spherical mirror of diameter 600 mm was measured to be 401.2 cm using the Ronchi test. The surface accuracy of ...
  • Optical to Far-IR Observations of 3C 446 
    Leech, K. J; Saxton, R; Barr, P; Santos-Lleo, M; Jiminez-Bailon; Soundararajaperumal, S (Astronomical Society of Australia, 2002)
    The OVV blazar 3C 446 was monitored over seven months in 1997 with ground based telescopes and instruments on ESA's Infrared Space Observatory (ISO). The aim was to try to detect variations in the IR and see if these were ...
  • Optical Tracking of Artificial Satellites 
    Bappu, M. K. V (NISCAIR, 1958)
  • Optical Transmission Spectra of Hot Jupiters: Effects of Scattering 
    Sengupta, S; Chakrabarty, Aritra; Tinetti, Giovanna (IOP Publishing, 2020-02-01)
    We present new grids of transmission spectra for hot Jupiters by solving the multiple-scattering radiative transfer equations with non-zero scattering albedo instead of using the Beer–Bouguer–Lambert law for the change in ...
  • Optical Variability of BL Lacertae during the Major Outburst of 1997 
    Ghosh, K. K; Ramsey, B. D; Sadun, A. C; Soundararajaperumal, S; Wang, J (The American Astronomical Society, 2000-07)
    We have undertaken an investigation of recent flux variability in BL Lac. We present optical observations taken over 22 nights documenting major as well as minor outbursts. This has been combined, for purposes of multifrequency ...
  • 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)

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