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Browsing by Author "Sankarasubramanian, K"

Browsing by Author "Sankarasubramanian, K"

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  • On the performance of a dual-beam polarimeter at Kodaikanal tower telescope 
    Nagaraju, K; Sankarasubramanian, K; Rangarajan, K. E; Ramesh, K. B; Singh, J; Devendran, P; Hariharan (Astronomical Society of India, 2008-09)
    Calibration and characterization of a dual-beam polarimeter installed at Kodaikanal Tower Telescope (KTT) for spectropolarimetric observations are presented in this paper. It was found that a slit width of 48 μ is optimum ...
  • On the Weakening of the Chromospheric Magnetic Field in Active Regions 
    Nagaraju, K; Sankarasubramanian, K; Rangarajan, K. E (The American Astronomical Society, 2008-05)
    Simultaneous measurement of line-of-sight (LOS) magnetic and velocity fields at the photosphere and chromosphere are presented. The Fe i line at λ6569 and Hα at λ6563 are used for deriving the physical parameters at ...
  • Onboard Automated CME Detection Algorithm for the Visible Emission Line Coronagraph on ADITYA-L1 
    Ritesh Patel; Amareswari, K; Pant, v; Banerjee, D; Sankarasubramanian, K; Amit Kumar (Springer, 2018-07)
    ADITYA-L1 is India’s first space mission to study the Sun from the Lagrange 1 position. The Visible Emission Line Coronagraph (VELC) is one of seven payloads on the ADITYA-L1 mission, which is scheduled to be launched ...
  • Photometry of Solar Corona to Study the Coronal Structures 
    Chakraborty, P; Sankarasubramanian, K; Majumder, S; Rajesh Nayak, K; Sridharan, R; Jana, A. D; Rajalakshmi, G; Suresh, D; Asgekar, A; Geetha, K. P; Rajesh, C. K (Indian Institute of Astrophysics, Bangalore, 1997)
    White light images of the solar corona were taken on KODAK 2415 films using 3-inch (f/11.5) telescopes fitted with SLR cameras. Observations were made from 4 different sites spread over the totality belt by four different ...
  • Polarization signatures of Mars dust and clouds: prospects for future spacecraft observations 
    Jaiswal, Bhavesh; Mahapatra, G; Nandi, Anuj; Sudhakar, M; Sankarasubramanian, K; Sheel, V (Elsevier B. V, 2021-07)
    The study of polarized sunlight scattered from planetary atmospheres provides diagnostic tools that can help explore the possible composition and size distribution of clouds and aerosol particles. Previous studies have ...
  • Polarized line formation in spherically symmetric atmospheres with velocity fields 
    Megha, A; Sampoorna, M; Nagendra, K. N; Anusha, L. S; Sankarasubramanian, K (IOP Publishing, 2019-07-01)
    The plane–parallel approximation of the stellar atmospheres cannot be applied to model the formation of optically thick lines formed in extended atmospheres. To a good approximation these atmospheres can be represented by ...
  • Polarized line formation in spherically symmetric expanding atmospheres 
    Megha, A; Sampoorna, M; Nagendra, K. N; Anusha, L. S; Sankarasubramanian, K (Astronomical Society of the Pacific, 2019-07)
    We consider the problem of polarized line formation in the spherically symmetric expanding atmospheres. The velocity fields in line forming regions produce Doppler shift, aberration of photons and also gives rise to ...
  • Proposed visible emission line space solar coronagraph 
    Singh, J; Prasad, B. R; Venkatakrishnan, P; Sankarasubramanian, K; Banerjee, D; Bayanna, R; Mathew, S; Murthy, J; Subramaniam, P; Ramesh, R; Kathiravan, S; Nagabhushana, S; Mahesh, P. K; Manoharan, P. K; Uddin, W; Sriram, S; Amit Kumar; Srivastava, N; Koteswara Rao; Nagendra, C. L; Chakraborty, P; Sriram, K. V; Venkateswaran, R; Krishnamurthy, T; Sreekumar, P; Sarma, K. S; Murthy, R; Navalgund, K. H; Samudraiah, D. R. M; Narayan Babu, P; Patra, A (Indian Academy of Sciences, 2011-01-25)
    The outer atmosphere of the sun – called the corona – has been observed during total solar eclipse for short periods (typically < 6 min), from as early as the eighteenth century. In the recent past, space-based instruments ...
  • Relation between solar flares and halo coronal mass ejections 
    Koteswara Rao, V; Rama Gopal, K; Ramakrishna Reddy, R; Amareswari, K; Sankarasubramanian, K (Indian Academy of Sciences, 2019-02)
    Solar flares and coronal mass ejections (CMEs) are two very important active events from Sun. Inspite of several theoretical and statistical analyses, the relation between solar flares and CMEs is so far not well ...
  • Solar G-band observations at Merak, Leh/Ladakh 
    Vasantharaju, N; Dorjey, N; Ravindra, B; Prabhu, K; Rangarajan, K. E; Prabhu Ramkumar, B; Sankarasubramanian, K (Indian Institute of Astrophysics, 2012)
    G-band observations are important for the study of dynamics of magnetic features in the solar photosphere and they are carried out using large telescopes, larger than 30 cm. We installed a 40 cm DFM telescope at one of ...
  • Solar polarimetry: techniques and applications 
    Sankarasubramanian, K (Indian Institute of Astrophysics, Bangalore, 2000-08)
  • The Solar Ultra-Violet Imaging Telescope (SUIT) Onboard Intelligence for Flare Observations 
    Varma, Manoj; Padinhatteri, Sreejith; Sinha, Sakya; Tyagi, Anurag; Burse, Mahesh; Yadav, Reena; Kumar, Ghanshyam; Ramaprakash, Anamparambu; Tripathi, Durgesh; Sankarasubramanian, K; Nagaraju, K; Vadodariya, Koushal; Tadepalli, Srikar; Deogaonkar, Rushikesh; Olekar, Manjunath; Azaruddin, Mohamed; Unnikrishnan, Amrita (Springer, 2023-02)
    Aditya-L1 is India’s first observatory-class solar space mission to study the Sun from the Lagrange L1 point. The Solar Ultra-Violet Imaging Telescope (SUIT) is one of the payloads onboard Aditya-L1. SUIT is an off-axis ...
  • The Solar Ultraviolet Imaging Telescope: detector characterization and readout electronics testing 
    Varma, Manoj; Tyagi, Anurag; Joshi, Bhushan; Yadav, Reena; Chordia, Pravin; Kumar, Ghanshyam; Sinha, Sakya; Burse, Mahesh; Padinhatteri, Sreejith; Deogaonkar, Rushikesh; Ramaprakash, A. N; Ghosh, Avyarthana; Tripathi, Durgesh; Sarkar, Janmejoy; Sankarasubramanian, K; Nagaraju, K; Vadodariya, Koushal; Kesharwani, Ravi; Khan, Aafaque; Olekar, Manjunath; Azaruddin, Mohamed (Oxford University Press on behalf of the Royal Astronomical Society, 2023-01)
    The Solar Ultraviolet Imaging Telescope (SUIT) is one of the payloads onboard the Aditya-L1 mission. It will perform full disc imaging of the Sun in the near-ultraviolet (UV) wavelength range of 200–400 nm. This provides ...
  • SoLEXS - A low energy X-ray spectrometer for solar coronal studies 
    Sankarasubramanian, K; Ramadevi, M. C; Bug, M; Umapath, C. N; Seetha, S; Sreekumar, P; Kumar (Astronomical Society of India, 2011)
    A Solar Low-energy X-ray Spectrometer (SoLEXS), a high spectral resolution (≤ 250 eV at 5.9 keV) instrument with soft X-ray energy coverage (≤ 1.5 keV), is being proposed as an additional payload on-board Aditya-1. The ...
  • Spectropolarimetry of an active region at the photosphere and chromosphere 
    Nagaraju, K; Sankarasubramanian, K; Rangarajan, K. E (Astronomical Society of the Pacific, 2009-06)
    Initial results on the simultaneous spectropolarimetric observations of an active region at the photosphere and chromosphere are presented. For this purpose, the Fe I line at λ6569 and the H I at λ6563 (Hα) are used. ...
  • Spectropolarimetry with the NLST 
    Sankarasubramanian, K; Hasan, S. S; Rangarajan, K. E (Springer, 2010)
    India’s National Large Solar Telescope (NLST) will provide opportunities to observe the Sun with high spatial, spectral, and polarimetric resolution. The large aperture also enables high-cadence spectropolarimetry with ...
  • Transit of Venus on 2012 June 06: stray light estimation and restoration of Ca-K images of Twin Telescope from Kodaikanal Observatory 
    Prabhu, K; Rangarajan, K. E; Ravindra, B; Sankarasubramanian, K; Selvendran, R; Kumaravel, P (Astronomical Society of India, 2013-09)
    Observations of the transit of Venus were made from the Kodaikanal Observatory on 2012 June 06 in Ca-K wavelengths. Only half of the event was visible from India. We utilized this unique opportunity to compute the contribution ...
  • UVIT observations of the star-forming ring in NGC 7252: Evidence of possible AGN feedback suppressing central star formation 
    George, K; Joseph, P; Mondal, Chayan; Devaraj, A; Subramaniam, A; Stalin, C. S; Cote, P; Ghosh, S. K; Hutchings, J. B; Mohan, Rekhesh; Postma, J; Sankarasubramanian, K; Sreekumar, P; Tandon, S. N (EDP Sciences, 2018-05)
    Context. Some post-merger galaxies are known to undergo a starburst phase that quickly depletes the gas reservoir and turns it into a red-sequence galaxy, though the details are still unclear. Aims. Here we explore the ...
  • X - ray spectrometers on - board Aditya - L1 for solar flare studies 
    Sankarasubramanian, K; Sudhakar, M; Sudhakar, M; Nandi, Anuj; Ramadevi, M. C; Adoni, A. A; Kushwaha, A; Agarwal, Anil; Dey, A; Joshi, B; Singh, Brajpal||Girish, V; Tomar, I; Majhi, K. K; Kumar; Olekar, Manjunath; Bug, M; Pala, Manohar; Thakur, Mukund Kumar; Badagandi, Rajeev R; Ravishankar, B. T; Garg, Sarthak; Sitaramamurthy, N; Sridhara, N; Umapathy, C. N; Gupta, Vinod Kumar; Agrawal, Vivek Kumar; Yougandar, B (Current Science Association, 2017-04)
    Aditya-L1 mission will carry two high-spectral resolution X-ray spectrometers to study solar flares. The soft X-ray spectrometer will cover the energy range from 1 to 30 keV, while the hard X-ray spectrometer will cover ...

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