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Paper: FUSE Observations of the He II Lyman alpha Forest towards HS 1700+6416
Volume: 348, Astrophysics in the Far Ultraviolet: Five Years of Discovery with FUSE
Page: 41
Authors: Reimers, D.; Fechner, C.; Kriss, G.; Shull, J.M.; Baade, R.; Moos, H.W.; Songaila, A.; Simcoe, R.
Abstract: We present FUSE observations of the He II Lyα forest in the redshift range 2.3 < z < 2.7 towards HS 1700+6416. Between October 2002 and February 2003, the brightness of the QSO increased by a factor 2. Therefore, with an exposure time of 203 ks during orbital night, the quality of the resulting spectrum is comparable to the HE 2347-4342 data. This second line of sight with a resolved He II Lyman alpha forest reveals a similar variation of several orders of magnitude of the column density ratio η = N(He II)/N(H I) and confirms the results of previous studies. The well-known metal line spectrum of HS 1700+6416 permits to examine the influence of metal line absorption on the He II column densities.
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