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Träfflista för sökning "WFRF:(Lawrence S. S.) srt2:(1995-1999)"

Search: WFRF:(Lawrence S. S.) > (1995-1999)

  • Result 1-4 of 4
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1.
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2.
  • Erkens, U., et al. (author)
  • Monitoring of active galactic nuclei. VI. The quasar Mrk 876
  • 1995
  • In: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 296:1, s. 90-9898
  • Journal article (peer-reviewed)abstract
    • For pt. V see ibid., vol. 285, no. 3, p. 857-67 (1994). We present the results of a 6 month monitoring campaign of Mrk 876, a low luminosity quasar with M absap-24. High resolution spectroscopy and direct imaging in the Johnson filters B, V, R, I was carried out in the first half of 1990. Line and continuum light curves are presented. Mrk 876 showed a decrease of 17% in the continuum over the whole observing period whereas the line flux of Hbeta and Halpha stayed constant. This implies, that the radius of the broad line region is larger than 6 light months. Coadded spectra of Hbeta and Halpha are presented which confirm an extreme asymmetry of the line profiles to the red. With respect to much earlier spectra the line profiles changed considerably
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3.
  • Jakobsson, Andreas, et al. (author)
  • Two-Dimensional Capon Spectrum Analysis
  • 1999
  • Reports (other academic/artistic)abstract
    • We present a computationally efficient algorithm for computing the 2-D Capon spectral estimator. The implementation is based on the fact that the 2-D data covariance matrix will have a Toeplitz-Block-Toeplitz structure, with the result that the inverse covariance matrix can be expressed in closed form by using a special case of the Gohberg-Heinig formula that is a function of strictly the forward 2-D prediction matrix polynomials. Furthermore, we present a novel method, based on a 2-D lattice algorithm, to compute the needed forward prediction matrix polynomials and discuss the difference in the so-obtained 2-D spectral estimate as compared to the one obtained by using the prediction matrix polynomials given by the Whittle-Wiggins-Robinson algorithm. Numerical simulations illustrate the clear computational gain in comparison to both the well-known classical implementation and the method recently published by Liu et al.
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4.
  • Lagerkvist, C.-I., et al. (author)
  • Comet C/1996 R3
  • 1997
  • In: 1997IAUC.6564....1L.
  • Other publication (other academic/artistic)
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  • Result 1-4 of 4

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