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Browsing by Author "Sreekumar, P"

Browsing by Author "Sreekumar, P"

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  • Beyond AstroSat: astronomy missions under review 
    Sreekumar, P; Koteswara Rao, V (Indian Academy of Science, 2021-10)
    India has an expanding program in using space as a platform for research. Astrophysics research from satellites increasingly complement ground-based observations with unique wavelength coverage, more frequent temporal ...
  • C1XS results—first measurement of enhanced sodium on the lunar surface 
    Athiray, P. S; Narendranath, S; Sreekumar, P; Grande, M (Elsevier B.V, 2014-12)
    We describe the first unambiguous evidence of enhanced sodium on the lunar surface revealed by the Chandrayaan-1 X-ray Spectrometer (C1XS). The C1XS onboard the Chandrayaan-1 spacecraft was designed to map the surface ...
  • Diffuse gamma ray emission : Implications on cosmic ray origin 
    Sreekumar, P (Astronomical Society of India, 2002)
    The Compton Gamma Ray Observatory (CGRO) produced the first full sky survery in gamma rays resulting in significantly improved data on the spectral and spatial distribution of diffuse gamma-rays from our galaxy. The intense ...
  • Dissecting star formation in the "Atoms-for-Peace" galaxy UVIT observations of the post-merger galaxy NGC7252 
    George, K; Joseph, P; Cote, P; Ghosh, S. K; Hutchings, J. B; Mohan, Rekhesh; Postma, J; Sankarasubramanian, K; Sreekumar, P; Stalin, C. S; Subramaniam, A; Tandon, S. N (EDP Sciences, 2018-06)
    Context. The tidal tails of post-merger galaxies exhibit ongoing star formation far from their disks. The study of such systems can be useful for our understanding of gas condensation in diverse environments. Aims. The ...
  • Does black hole spin play a key role in the FSRQ/BL Lac dichotomy? 
    Bhattacharya, D; Sreekumar, P; Mukhopadhyay, B; Tomar, I (IOP Publishing, 2016-04)
    Blazars are characterized by large intensity and spectral v ariations across the electromagnetic spectrum It is believed that jets emerging from them are almo st aligned with the line-of-sight. The major- ity of ...
  • Elemental abundances in the solar corona as measured by the X-ray solar monitor onboard Chandrayaan-1 
    Narendranath, S; Sreekumar, P; Alha, L; Sankarasubramanian, K; Huovelin, J; Athiray, P. S (Springer, 2014-05)
    The X-ray Solar Monitor (XSM) on the Indian lunar mission Chandrayaan-1 was flown to complement lunar elemental abundance studies by the X-ray fluorescence experiment C1XS. XSM measured the ≈ 1.8 – 20 keV solar X-ray ...
  • Experimental validation of XRF inversion code for Chandrayaan-1 
    Athiray, P. S; Sudhakar, M; Tiwari, M. K; Narendranath, S; Lodha, G. S; Deb, S. K; Sreekumar, P; Dash, S. K (Elsevier B.V., 2013-12)
    We have developed an algorithm (x2abundance) to derive the lunar surface chemistry from X-ray fluorescence (XRF) data for the Chandrayaan-1 X-ray Spectrometer (C1XS) experiment. The algorithm converts the observed XRF line ...
  • Full Stokes polarimetry using dual-frequency liquid crystals 
    Nagaraju, K; Phanindra, D. V. S; Krishna Prasad, S; Shankar Rao, D. S; Sreekumar, P (SPIE-The International Society for Optical Engineering, 2018-07-06)
    In a dual-frequency liquid crystal (DFLC), when the frequency of the applied voltage is more than a critical value (fc), the dielectric anisotropy of the material changes from positive to negative. This causes the director ...
  • The Gamma Ray Burst experiment on the Indian SROSS C-2 satellite 
    Sinha, S; Sreekumar, P; Kasturirangan, K (Astronomical Society of India, 2001)
    The SROSS C-2 satellite launched by the ASLV carried aloft a CsI gamma ray burst detector. To date, 51 GRB events have been detected unambiguously with 22 being common with BATSE. The experiment with its 2 ms time resolution, ...
  • In-orbit Calibrations of the Ultraviolet Imaging Telescope 
    Tandon, S. N; Subramaniam, A; Girish, V; Postma, J; Sankarasubramanian, K; Sriram, S; Stalin, C. S; Mondal, Chayan; Sahu, S; Joseph, P; Hutchings, J; Ghosh, S. K; Barve, Indrajit V; George, K; Kamath, P. U; Kathiravan, S; Kumar, A; Lancelot, J. P; Leahy, D; Mahesh, P. K; Mohan, Rekhesh; Nagabhushana, S; Pati, A. K; Kameswara Rao, N; Sreedhar, Yuvraj Harsha; Sreekumar, P (IOP Publishing, 2017-09)
    The Ultra-Violet Imaging Telescope (UVIT) is one of the payloads in ASTROSAT, the first Indian Space Observatory. The UVIT instrument has two 375 mm telescopes: one for the far-ultraviolet (FUV) channel (1300–1800 Å), ...
  • In-orbit performance of UVIT and first results 
    Tandon, S. N; Hutchings, J. B; Ghosh, S. K; Subramaniam, A; George, K|; Girish, V; Kamath, P. U; Kathiravan, S; Kumar, A; Lancelot, J.P; Mahesh, P. K; Mohan, Rekhesh; Murthy, J; Nagabhushana, S; Pati, A. K; Postma, J; Kameswara Rao, N; Sankarasubramanian, K; Sreekumar, P; Sriram, S; Stalin, C. S; Sutaria, F. K; Sreedhar, Yuvraj Harsha; Barve, Indrajit V; Mondal, Chayan; Snehalata Sahu (Indian Academy of Sciences, 2017-06)
    The performance of the ultraviolet telescope (UVIT) on-board AstroSat is reported. The performance in orbit is also compared with estimates made from the calibrations done on the ground. The sensitivity is found to be ...
  • In-orbit performance of UVIT over the past 5 years 
    Ghosh, S. K; Joseph, P; Kumar, A; Postma, J; Stalin, C. S; Subramaniam, A; Tandon, S. N; Barve, Indrajit V; Devaraj, A; George, K; Girish, V; Hutchings, J. B; Kamath, P. U; Kathiravan, S; Lancelot, J. P; Leahy, D; Mahesh, P. K; Mohan, R; Nagabhushana, S; Pati, A. K; Kameswara Rao, N; Sankarasubramanian, K; Sreekumar, P; Sriram, S (Indian Academy of Sciences, 2021-10)
    Over the last 5 years, UVIT has completed observations of more than 500 proposals with ∼800 unique pointings. In addition, regular planned monitoring observations have been made and from their analysis various key parameters ...
  • Indian Institute of Astrophysics Academic Report: 2013-14 
    Sreekumar, P (Indian Institute of Astrophysics, 2014)
  • Indian Institute of Astrophysics Annual Report: 2014-15 
    Sreekumar, P (Indian Institute of Astrophysics, 2015)
  • Indian Institute of Astrophysics Annual Report: 2015-16 
    Sreekumar, P (Indian Institute of Astrophysics, 2016)
  • Indian Institute of Astrophysics Annual Report: 2016-17 
    Sreekumar, P (Indian Institute of Astrophysics, 2017)
  • Indian Institute of Astrophysics Annual Report: 2017-18 
    Sreekumar, P (Indian Institute of Astrophysics, 2018)
  • Indian Institute of Astrophysics Annual Report: 2018-19 
    Sreekumar, P (Indian Institute of Astrophysics, 2019)
  • Multilayer Mirror Based High-Resolution Solar Soft X-Ray Spectrometer 
    Panini, S. S; Narendranath, S; Sreekumar, P; Sankarasubramanian, K (Frontiers Media S.A, 2021-07)
    Soft X-ray spectroscopy of the Sun is an important tool to understand the coronal dynamics and composition. The solar coronal X-ray spectrum below 1 keV is the least explored with high-resolution spectroscopy. Recent ...
  • Multilayer mirror-based soft x-ray polarimeter for astronomical observations 
    Panini, S. S; Sreekumar, P; Marshall, H. L; Narendranath, S; Nayak, M; Athiray, P. S (SPIE-The International Society for Optical Engineering, 2018-01)
    A simple design of a soft x-ray polarimeter using multilayer mirrors is presented. A multilayer mirror acts as a linear polarization analyzer for x-rays at incidence angles close to the Brewster angle. The instrument ...

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