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Browsing by Author "Banyal, R. K"

Browsing by Author "Banyal, R. K"

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  • Development of a stabilized fabry-perot based wavelength calibrator for precision doppler spectroscopy 
    Tanya, Das; Banyal, R. K; Kathiravan, S; Sivarani, T; Ravindra, B (SPIE-The International Society for Optical Engineering, 2018-07-06)
    Precision Doppler spectroscopy serves as an important tool for Radial Velocity (RV) observations of stars. High precision spectroscopy is bound by two major challenges, first being the instrument instability which is ...
  • Development of a temperature controller for the order-sorting interference filters 
    Banyal, R. K; Ravindra, B (Indian Institute of Astrophysics, 2012-08-01)
    A Fabry-Perot narrow band imager (NBI) is being built for solar studies at IIA [1]. The NBI has an order sorting pre- lter that selects an optical beam within desired wavelength band. A constant temperature is required ...
  • Development of image motion compensation system for 1.3m telescope at Vainu Bappu Observatory 
    Sreekanth Reddy, V; Banyal, R. K; Sridharan, R; Aishwarya, S (IOP Publishing, 2020-01-01)
    We developed a tip-tilt system to compensate the turbulence induced image motion for the 1.3 m telescope at Vainu Bappu Observatory, at Kavalur. The instrument is designed to operate at the visible wavelength band (480−700 ...
  • Diffraction by ruled gratings with variable spacing: fundamental method of intensity calculation 
    Chatterjee, S; Vani, V. C; Haghighi, Rezvan R; Banyal, R. K (Optical Society of America, 2019-11-01)
    A regular diffraction grating produces intensity patterns that combine waves coming through equispaced slits, so that the waves emerging from any two neighboring slits have identical phase differences. In this paper, we ...
  • A dual cavity Fabry-Perot device for high precision doppler measurements in astronomy 
    Banyal, R. K; Reiners, A (World Scientific Publishing Co., 2017-03)
    We propose a dual cavity Fabry–Perot interferometer as a wavelength calibrator and a stability tracking device for astronomical spectrograph. The FPI consists of two adjoining cavities engraved on a low expansion monoblock ...
  • A Dual Fabry-Perot based imaging Spectrometer for the National Large Solar Telescope 
    Ravindra, B; Banyal, R. K (Indian Institute of Astrophysics, 2010)
    This report provides a detailed design of a dual Fabry-Perot based narrow band imaging system intended to make observations of solar atmosphere at visible and near infrared wavelengths. The narrow band imager will serve ...
  • A dual Fabry-Perot based narrow band imager for the National Large Solar Telescope 
    Ravindra, B; Banyal, R. K (Astronomical Society of India, 2011)
    A large solar telescope is usually equipped with several postfocus instruments deployed to study the dynamics of the solar features at di erent wavelengths. Indian Institute of Astrophysics (IIA) has proposed to build ...
  • Estimation and correction of the instrumental perturbations of Vainu Bappu Telescope Echelle spectrograph using a model-based approach 
    Chamarthi, Sireesha; Banyal, R. K; Sriram, S (SPIE-The International Society for Optical Engineering, 2019-11)
    The Echelle spectrograph operating at Vainu Bappu Telescope (VBT), India, is a general purpose instrument used for many high-resolution spectroscopic observations. A concerted effort is being made to expand the scientific ...
  • Estimation of asymmetries in point spread function for the echelle spectrograph operating at Vainu Bappu Telescope for high precision radial velocity studies 
    Sireesha, C; Banyal, R. K; Sriram, S (SPIE--The International Society for Optical Engineering, 2018-07)
    Precision in the Radial Velocity (RV) measurements depends upon the efficiency of the technique to remove instrumental artifacts from stellar measurements. Iodine absorption cell technique is being implemented for high ...
  • Fabry-Perot based narrow band imager for solar filament observations 
    Sajal Kumar Dhara; Ravindra, B; Banyal, R. K (IOP Publishing, 2016-01)
    We have recently developed a narrow band imager (NBI) using a n air gap based Fabry-P ́erot (FP) interferometer at the Indian Institute of Astrophysic s, Bangalore. Narrow band imaging is achieved by using an FP ...
  • Filament Eruption in Association with Rotational Motion Near the Filament Footpoints 
    Dhara, Sajal Kumar; Ravindra, B; Banyal, R. K (Elsevier B.V., 2014-01)
    The active region magnetic field surrounding the filament plays an important role in filament formation, their evolution and disruption. We investigated a filament eruption that occurred in southern hemisphere of the Sun ...
  • From the margins to the mainstream: Nobel celebrates exoplanets! 
    Puravankara, Manoj; Banyal, R. K; Narang, Mayank (Indian Physics Association, 2019-12)
    This year’s Physics Nobel Prize was jointly awarded to three scientists. Phillip James Peebles from Princeton University, USA, received one half of the prize for his seminal work on physical cosmology, and other half was ...
  • Galactic Chemical Evolution of Exoplanet Hosting Stars: Are High-mass Planetary Systems Young? 
    Swastik, C; Banyal, R. K; Narang, Mayank; Manoj, P; Sivarani, T; Rajaguru, S. P; Athira Unni; Banerjee, Bihan (American Astronomical Society, 2022-08-01)
    The imprints of stellar nucleosynthesis and chemical evolution of the galaxy can be seen in different stellar populations, with older generation stars showing higher α-element abundances and the later generations ...
  • High-contrast, all-optical switching in bacteriorhodopsin films 
    Banyal, R. K; Prasad, B. R (Optical Society of America, 2005-09)
    We report experiments with nonlinear-absorption-based, high-contrast, all-optical switching in photochromic bacteriorhodopsin (BR) films. The switching action is accomplished by control of the transmission of a weak probe ...
  • Holographic recording in Fe:Ce:Ti doped LiNbO3 crystal 
    Banyal, R. K; Prasad, B. R (Elsevier, 2007-06)
    High diffraction efficiency measurements in a triply doped Fe:Ce:Ti LiNbO3 crystal are reported. The crystal shows an improved recording sensitivity, weak light-induced scattering and extremely slow readout erasure which ...
  • Host star metallicity of directly imaged wide-orbit planets: implications for planet formation 
    Swastik, C; Banyal, R. K; Narang, Mayank; Manoj, P; Sivarani, T; Reddy, B. E; Rajaguru, S. P (IOP Publishing, 2021-03-01)
    Directly imaged planets (DIPs) are self-luminous companions of pre-main-sequence and young main-sequence stars. They reside in wider orbits (~tens to thousands of astronomical units) and generally are more massive compared ...
  • In defence of scientific temper 
    Banyal, R. K (Indian Academy of Sciences, 2009-07-10)
  • Innovations and advances in instrumentation at the W. M. Keck Observatory, vol. II 
    Kassis, Marc F; Allen, Steve; Alvarez, Carlos; Banyal, R. K; Bertz, Robert; Beichman, Charles; Brown, Aaron; Brown, Matthew; Cabak, Gerald; Bundy, Kevin; Cetre, Sylvain; Chin, Jason; Chun, Mark; Deich, Will; Dekany, Richard; Delorme, Jacques; Devenot, Mark; Doppmann, Greg; Fitzgerald, Michael P; Fucik, Jason R; Hill, Grant; Hinz, Philip; Holden, Bradford P; Howard, Andrew; Gao, Maodong; Gibson, Steve; Gomez, Percy; Gottschalk, Colby; Gillingham, Peter R; Jones, Tucker; Jovanovic, Nemanja; Kirby, Evan; Konopacky, Quinn; Krishnan, Shanti; Kupke, Renate; Larkin, James E.; Leife, Stephanie D; Lewis, Hilton A; Lilley, Scott; Lu, Jessica; Lyk, James E; MacDonald, Nick; Marin, Eduardo; Matuszewski, Matt; Mawet, Dimitri; McGurk, Rosalie; A Millar-Blanchaer, Maxwell; Nash, Reston B; Nance, Craig; Neill, James D; M. O'Meara, John; Peretz, Eliad; Poppett, Claire L; Mather, John C; Radovan, Matthew V; Roberts, Mitsuko K; Ragland, Sam; Rider, Kodi; Rockosi, Constance M; Sandfor, Dale; Shen, Boqiang; Steidel, Charles C; Simha, Sunil; Skemer, Andy; Stelter, Deno; Surendran, Avinash; Thorne, James; McCarney, Ben; Lanclos, Kyle; Baker, Ashley; Rubenzah, Ryan; Roy, Arpita; Halverson, Sam; Edelstein, Jerry; Martin, Christopher; Savage, Maureen; Sandford, Dale; Sallum, Stephanie; Walawender, Josh; Wizinowich, Peter; Westfall, Kyle B; Vahala, Kerry J; Wright, Shelley; Wold, Truman; Yeh, Sherry (SPIE-The International Society for Optical Engineering, 2022-08)
    Since the start of science operations in 1993, the twin 10-meter W. M. Keck Observatory (WMKO) telescopes have continued to maximize their scientific impact and to produce transformative discoveries that keep the observing ...
  • Installation of solar chromospheric telescope at the Indian Astronomical Observatory, Merak 
    Ravindra, B; Prabhu, K; Thulasidharen, K. C; Rajalingam, M; Sagayanathan, K; Kamath, P. U; Dorjey, N; Angchuk, D; Kemkar, P. M. M; Dorjai, T; Banyal, R. K (Indian Academy of Sciences, 2018-10)
    We report the observations of the solar chromosphere from a newly commissioned solar telescope at the incursion site near Pangong Tso lake in Merak (Leh/Ladakh). This new Hα telescope at the Merak site is identical to the ...
  • Intensity profile of light scattered from a rough surface 
    Chatterjee, S; Vani, V. C; Banyal, R. K (Optical Society of America, 2013-08-20)
    We present in this paper, approximate analytical expressions for the intensity of light scattered by a rough surface, whose elevation ξ x; y in the z-direction is a zero mean stationary Gaussian random variable. With ...

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