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Browsing IIAP Publications by Title

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  • Determination of the choromospheric quiet network element area index and its variation during 2008 and 2011 
    Singh, J; Ravindra, B; Selvendran, R; Kumaravel, P; Priyal, M; Priya, T. G; Amareswari, K (Chinese Academy of Sciences, 2012-02)
    Generally it has been considered that the plages and sunspots are the main contributors to the solar irradiance. There are small scale structures on the sun with intermediate magnetic fields that could also contribute ...
  • Determination of the limb darkening of the solar disc in the visible and near ultraviolet 
    Bhattacharyya, J. C; Chandramohan, R; Sundareswaran, A; Charles, A (Indian National Science Academy, 1981)
  • Determination of the mean HI absorption of the intergalactic medium 
    Aghaee, A; Petitjean, P; Srianand, R; Stalin, C. S; Guimaraes, R (Indian Academy of Sciences, 2010-06)
    In recent years, the Lyman-α forest in quasar spectra has been used, together with N-body simulations, to determine the underlying matter distribution in the intergalactic medium (IGM). One of the key parameters to be ...
  • Determination of the size of the dust torus in H0507+164 through optical and infrared monitoring 
    Amit Kumar; Rakshit, S; Kshama, S. K; Stalin, C. S; Mathew, B; Hoenig, Sebastian; Gandhi, Poshak; Sagar, R; Pandge, M. B (Oxford University Press on behalf of the Royal Astronomical Society, 2018-04)
    The time delay between flux variations in different wavelength bands can be used to probe the inner regions of active galactic nuclei (AGNs). Here, we present the first measurements of the time delay between optical and ...
  • Determination of times of second and third contact from flash spectrum sequence 
    Bhatnagar, A. K (Indian Institute of Astrophysics, 1997)
    The predicted times of contact of a total solar eclipse have uncertainty of a few seconds due to (i) irregular profile of the lunar limb, (ii) difference between the geometrical and gravitational centres of the Moon's disc ...
  • Determining global parameters of the oscillations of solar-like stars 
    Mathur, S; Garcia, R. A; Regulo, C; Creevey, P. L; Ballot, J; Salabert, D; Arentoft, T; Quirion, P. O; Chaplin, W. J; Kjeldsen, H (EDP Sciences, 2010-02)
    Helioseismology has enabled us to better understand the solar interior, while also allowing us to better constrain solar models. But now is a tremendous epoch for asteroseismology as space missions dedicated to studying ...
  • Determining Interstellar Carbon Abundances from Strong-line Transitions 
    Sofia, U. J; Parvathi, V. S; Babu, B. R. S; Murthy, J (IOP Publishing, 2011-01)
    Carbon is arguably the most important element in the interstellar medium, yet its abundance in gas and dust is poorly understood due to a paucity of data. We explore the possibility of substantially increasing our knowledge ...
  • Determining the variations of Ca–K index and features using century-long equal-contrast images from Kodaikanal observatory 
    Singh, J; Priyal, M; Ravindra, B (IOP Publishing, 2021-02-20)
    In an earlier analysis of Ca–K spectroheliograms obtained at the Kodaikanal Observatory, the "Good" images were used to investigate variations in the chromosphere. However, the contrast of the images varied on a day-to-day ...
  • Deuteron photodisintegration with polarized photons at astrophysical energies 
    Ramachandran, G; Shilpashree, S. P (The American Physical Society, 2006-11)
    Following precise experimental studies at the Duke Free-Electron Laser Laboratory, we discuss the photodisintegration of deuterons with 100% linearly polarized photons using a model independent theoretical approach taking ...
  • Developing scanning-slit spectrograph for imaging the Sun 
    Pruthvi, H; Ramesh, K. B; Dhara, Sajal Kumar; Ravindra, B (SPIE--The International Society for Optical Engineering, 2016-08)
    For moderate resolution spectroscopy of the Sun, an imaging spectrograph is being developed at Indian Institute of Astrophysics. With this instrument images of the region of interest of the Sun can be obtained with low ...
  • Development of a code to analyze the solar white-light images from the Kodaikanal Observatory: detection of sunspots, computation of heliographic coordinates and area 
    Ragadeepika, P; Hiremath, K. M; Gurumath, S. R (Indian Academy of Sciences, 2016-03)
    Sunspots are the most conspicuous aspects of the Sun. They have a lower temperature, as compared to the surrounding photosphere; hence, sunspots appear as dark regions on a brighter background. Sunspots cyclically appear ...
  • Development of a Lunar Scintillometer as part of the national large optical telescope site survey 
    Surendran, A; Parihar, P. S; Banyal, R. K; Anusha Kalyaan (Springer, 2018-03)
    Ground layer turbulence is a very important site characterization parameter used to assess the quality of an astronomical site. The Lunar Scintillometer is a simple and effective site-testing device for measuring the ...
  • Development of a Speckle Interferometer and the Measurement of Fried's Parameter (ro) at the Telescope Site 
    Saha, S. K; Sudheendra, G; Chandra, A. U; Chinnappan, V (Kluwer Academic Publishers, 1999)
    A new optical speckle interferometer for use at the 2.34 meter Vainu Bappu Telescope (VBT), at Vainu Bappu Observatory (VBO), Kavalur, India, has been designed and developed. Provisions have been made for observation both ...
  • 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 an active-optics system for 27-inch thin mirror 
    Saxena, A. K; Lancelot, J. P; Samson, J. P (SPIE-The International Society for Optical Engineering, 1993-12)
    India is planning to build a large Optical/Infrared Telescope of 4 to 5 M in size. This telescope will adopt most of the features of the New Technology Telescope including active and adoptive optics corrections for achieving ...
  • Development of Data Acquisition Methods for an FPGA-Based Photon Counting Detector 
    Ambily, S; Mayuresh, Sarpotdar; Mathew, J; Sreejith, A. G; Nirmal, K; Prakash, A; Safonova, M; Murthy, J (World Scientific Publishing Co., 2017-03)
    MCP-based detectors are widely used in the ultraviolet (UV) region due to their low noise levels, high sensitivity and good spatial and temporal resolution. We have developed a compact near-UV (NUV) detector for highaltitude ...
  • The development of HISPEC for Keck and MODHIS for TMT: science cases and predicted sensitivities 
    Konopacky, Quinn M; Baker, Ashley D; Mawet, Dimitri; Fitzgerald, Michael P; Jovanovic, Nemanja; Beichman, Charles; Ruane, Garreth; Bertz, Rob; Terada, Hiroshi; Dekany, Richard; Lingvay, Larry; Kassis, Marc; Anderson, David; Tamura, Motohide; Benneke, Bjorn; Beatty, Thomas; Do, Tuan; Nishiyama, Shogo; Plavchan, Peter; Wang, Jason; Wang, Ji; Burgasser, Adam; Ruffio, Jean-Baptiste; Zhang, Huihao; Brown, Aaron; Fucik, Jason; Gibbs, Aidan; Gibson, Rose; Halverson, Sam; Johnson, Christopher; Karkar, Sonia; Kotani, Takayuki; Kress, Evan; Leifer, Stephanie; Magnone, Kenneth; Maire, Jerome; Pahuja, Rishi; Porter, Michael; Roberts, Mitsuko; Sappey, Ben; Thorne, Jim; Wang, Eric; Artigau, Etienne; Blake, Geoffrey A; Canalizo, Gabriela; Chen, Guo; Doppmann, Greg; Doyon, Rene; Dressing, Courtney; Fang, Min; Greene, Thomas; Herczeg, Greg; Hillenbrand, Lynne; Howard, Andrew; Kane, Stephen; Kataria, Tiffany; Kempton, Eliza; Knutson, Heather; Lafrenière, David; Liu, Chao; Metchev, Stanimir; Millar-Blanchaer, Max; Narita, Norio; Pandey, G; Rajaguru, S. P; Robertson, Paul; Salyk, Colette; Sato, Bun’ei; Schlawin, Evertt; Sengupta, S; Sivarani, T; Skidmore, Warren; Vasisht, Gautam; Yasui, Chikako; Zhang, Hui (SPIE-The International Society for Optical Engineering, 2023-10)
    HISPEC is a new, high-resolution near-infrared spectrograph being designed for the W.M. Keck II telescope. By offering single-shot, R 100,000 spectroscopy between 0.98 – 2.5 µm, HISPEC will enable spectroscopy of transiting ...
  • 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 ...
  • Development of Polishing Procedure for Producing Highly Specularly Reflecting Surface for Sun Shield Panels of INSAT II TS VHRR Radiant Cooler 
    Saxena, A. K (Indian Institute of Astrophysics, Bangalore, 1991)
    VIRR Radient Cooler used for cooling of infrared detector of VHRR instrument onboard INDIAN NATIONAL SATELLITE [INSAT II] is being developed at Thermal Systems Division of ISAC/ISRO, Bangalore. This development work is ...
  • Development of sunshield panels for passive radiant cooler on board meteorological instruments of ISRO 
    Madhu Prasad; Akkimaradi, B. S; Santram; Selvan, T; Subramanya; Rastogi, S. C; Badrinarayana, K; Bhandari, D. R; Sugumar, M; Mallesh, B; Rajam, K. S; Indira Rajgopalan; Grips, V. K. W; Balaraju, J. N; Saxena, A. K; Ismail Jabilullah, R; Viswanathan, M; Shanbhog, G (2009)
    Radiant cooler is used to cool the infrared and water vapour detectors of meteorological payload. It consists of patch (cold stage) on which detector is mounted, intermediate cooling stage radiator, vacuum housing to enclose ...

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