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Browsing by Author "Nagaraju, K"

Browsing by Author "Nagaraju, K"

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  • High-resolution, high-sensitivity, ground-based solar spectropolarimetry with a new fast imaging polarimeter: I .Prototype characterization 
    Iglesias, F. A; Feller, A; Nagaraju, K; Solanki, S. K (EDP Sciences, 2016-06)
    Remote sensing of weak and small-scale solar magnetic fields is of utmost relevance when attempting to respond to a number of important open questions in solar physics. This requires the acquisition of spectropolarimetric ...
  • Hα full line spectropolarimetry as diagnostics of chromospheric magnetic field 
    Nagaraju, K; Sankarasubramanian, K; Rangarajan, K. E (Indian Academy of Sciences, 2020-12)
    Analysis of spectropolarimetric observations of two circular sunspots located close to disk centre in Hα (6562.8 Å) and Fe i (6569.22 Å) is presented in this paper. The corresponding active region numbers areNOAA 10940 and ...
  • An Image Auto Guider System for Kodaikanal Tower Tunnel Telescope 
    Mathur, Harsh; Thulasidharen, K. C; Hemanth, P; Nagaraju, K; Rajalingam, M (World Scientific Publishing, 2023-02)
    The Kodaikanal Tower Tunnel Telescope (KTT) is a three-mirror Coelostat-based Solar telescope. An inherent variable image drift is present in the KTT which is detrimental to observations particularly to slit-based spectroscopic ...
  • Magnetic and velocity properties of G-band bright points around a pore 
    Rangarajan, K. E; Sankarasubramanian, K; Nagaraju, K (Astronomical Society of the Pacific, 2009-06)
    Physical properties of G-band bright points (GBPs) surrounding a pore are studied using observations spanning from photosphere to chromosphere. The magnetic field strengths obtained in these bright points are of the order ...
  • 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 Variability of the Solar Mean Magnetic Field: Contributions from Various Magnetic Features on the Surface of the Sun 
    Souvik Bose; Nagaraju, K (IOP Publishing, 2018-07-20)
    The solar mean magnetic field (SMMF) is referred to as the disk-averaged line-of-sight (LOS) magnetic field that also reflects the polarity imbalance of the magnetic field on the Sun. The origin of the SMMF has been debated ...
  • 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 ...
  • Properties of shock waves in the quiet-Sun chromosphere 
    Mathur, Harsh; Joshi, Jayant; Nagaraju, K; van der Voort, Luc Rouppe; Bose, Souvik (EDP Sciences, 2022-12)
    Context. Short-lived (100 s or less), sub-arcsec to a couple of arcsec sized features of enhanced brightenings in the narrowband images at the H2V and K2V positions of the Ca ii H&K lines in the quiet Sun are known as ...
  • Smear correction of highly variable, frame-transfer CCD images with application to polarimetry 
    Iglesias, F. A; Feller, A; Nagaraju, K (Optical Society of America, 2015-07-01)
    Image smear, produced by the shutterless operation of frame-transfer CCD detectors, can be detrimental for many imaging applications. Existing algorithms used to numerically remove smear do not contemplate cases where ...
  • Solar mean magnetic field of the chromosphere 
    Vishnu, M; Nagaraju, K; Mathur, Harsh (Indian Academy of Sciences, 2023-12)
    The Solar Mean Magnetic Field (SMMF) is the mean value of the line-of-sight (LOS) component of the solar vector magnetic field averaged over the visible hemisphere of the Sun. So far, the studies on SMMF have mostly been ...
  • Solar spectropolarimetry of Ca II 8542 Å line: polarimeter development, calibration, and preliminary observations 
    Hemanth, P; Nagaraju, K; Ravindra, B; Ramesh, K. B (SPIE-The International Society for Optical Engineering, 2018-11)
    Chromospheric magnetic fields are of paramount importance in understanding the dynamics of energetic events in the solar atmosphere. At the Kodaikanal Solar Observatory, several polarimeters were developed in the past to ...
  • 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 ...
  • Spectral Lines in FUV and EUV for Diagnosing Coronal Magnetic Field 
    Raveena, Khan; Nagaraju, K (Springer Nature, 2022-07)
    The diagnostic capabilities of spectral lines in the far-ultraviolet (FUV) and extremeultraviolet (EUV) wavelength ranges are explored in terms of their Hanle and Zeeman sensitivity to probe the vector magnetic fields in ...
  • Spectropolarimeter on board the Aditya-L1: polarization modulation and demodulation 
    Nagaraju, K; Prasad, B. R; Hegde, Bhavana S; Venkata Suresh, Narra; Utkarsha, D; Kumar, Amit; Singh, J; Kumar, Varun (Optical Society of America, 2021-09-10)
    One of the major science goals of the Visible Emission Line Coronagraph (VELC) payload aboard the Aditya-L1 mission is to map the coronal magnetic field topology and quantitative estimation of longitudinal magnetic field ...
  • Spectropolarimetry of Active Regions on the Sun 
    Nagaraju, K (Indian Institute of Astrophysics, 2008-06)
  • 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. ...
  • Spectroscopic Observation of Oscillations in the Corona During the Total Solar Eclipse of 22 July 2009 
    Singh, J; Hasan, S. S; Gupta, G. R; Nagaraju, K; Banerjee, D (Springer, 2011-05)
    We performed high resolution spectroscopy of the solar corona during the total solar eclipse of 22 July 2009 in two emission lines: the green line at 5303 Å due to Fe xiv and the red line at 6374 Å due to Fe x, simultaneously ...

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