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Date and Time of the Query: 2019-08-22 T08:20:45 PDT
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For refcode 1996ApJ...467..622K:
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Copyright by American Astronomical Society. Reproduced by permission
1996ApJ...467..622K FAR-ULTRAVIOLET OBSERVATIONS OF NGC 3516 USING THE HOPKINS ULTRAVIOLET TELESCOPE G. A. KRISS, B. R. ESPEY, J. H. KROLIK, Z. TSVETANOV, W. ZHENG, AND A. F. DAVIDSEN Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 Received 1996 January 4; accepted 1996 March 7 ABSTRACT We observed the Seyfert 1 galaxy NGC 3516 twice during the flight of Astro-2 using the Hopkins Ultraviolet Telescope aboard the Space Shuttle Endeavour in March 1995. Simultaneous X-ray observations were performed with the Advanced Satellite for Cosmology and Astrophysics. Our far- ultraviolet spectra cover the spectral range 820-1840 A, with a resolution of 2-4 A. No significant variations were found between the two observations. The total spectrum shows a red continuum, f_{nu}_ ~ {nu}^- 1.89^, with an observed flux of 2.2 x 10^-14^ ergs cm^-2^ s^-1^ A^-1^ at 1450 A, slightly above the historical mean. Intrinsic absorption in Ly{beta}_ is visible as well as absorption from O VI {lambda}{lambda}1032, 1038, N V {lambda}{lambda}1239, 1243, Si IV {lambda}{lambda}1394,1403, and C IV {lambda}{lambda}1548,1551. The UV absorption lines are far weaker than is usual for NGC 3516 and also lie closer to the emission-line redshift rather than showing the blueshift typical of these lines when they are strong. The neutral hydrogen absorption, however, is blueshifted by 400 km s^-1^ relative to the systemic velocity, and it is opaque at the Lyman limit. The sharpness of the cutoff indicates a low effective Doppler parameter, b < 20 km s^-1^. For b = 10 km s^-1^, the derived intrinsic column density is 3.5 x 10^17^ cm^-2^. As in NGC 4151, a single warm absorber cannot produce the strong absorption visible over the wide range of observed ionization states. Matching both the UV and X-ray absorption simultaneously requires absorbers spanning a range of 10^3^ in both ionization parameter and column density. Subject headings: galaxies: active galaxies: individual (NGC 3516) galaxies: nuclei galaxies: Seyfert - ultraviolet: galaxies
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