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Q 0002+051
V = 16.2; z = 1.899; exp = 2700 s; coverage = 3655.7-6079.0 A
Spectra of this QSO, also known as UM 18 and PHL 957, were previously studied by Young, Sargent, & Boksenberg (1982, YSB), Lanzetta, Turnshek, & Wolfe (1987, LTW), and Steidel & Sargent (1992, SS92). An additional Mg II absorber at z = 0.2980 has been discovered by [Steidel, Dickinson, and Persson 1994 (SDP); Steidel, private communication], but was not observed because it was not covered by the HIRES format. The C IV doublet at z = 1.7444 reported by YSB has been observed, but is not published here.
z=0.591485 |DATA & VOIGT PROFILES| |EWs & AOD COLUMNS| |VP PARAMETERS|
This system was discovered by SDP (Steidel, private communication). The absorption profile is found to be a single VP component. However, both transitions of the doublet exhibit an asymmetry in the blue wing that is difficult to understand unless the absorbing gas is extremely quiescent. The Fe II 2344 transition and the Ca II 3934, 3969 doublet were not covered by the HIRES format. The Mn II triplet and all other Fe II transitions showed no absorption to the EW(rest) limits given in Table 3.6.
z=0.851394 |DATA & VOIGT PROFILES| |EWs & AOD COLUMNS| |VP PARAMETERS|This system was first reported by SS92, and turns out to be one of the most kinematically intriguing absorption profiles of the entire sample, with a total velocity spread of roughly 475 km/s. It is difficult to understand this profile in terms of gas gravitationally bound to a single galactic halo. The overall profile was found to have four kinematically distinct features and was fitted with a total of 12 VP components. The Ca II 3934, 3969 doublet was not covered by the HIRES format. The Mn II triplet showed no absorption to the EW(rest) limits given in Table 3.7.
Special Note on Sky Subtraction and Zero PointOnly a single exposure on this QSO was obtained so that removing cosmic rays, especially from the sky, was very problematic. A first-pass QSO spectrum was extracted with no sky subtraction, so that cosmic rays in the sky would not contaminate the resulting spectrum. Then, a second--pass extraction was performed with sky subtraction, in order to obtain the sky spectrum itself. This sky spectrum was then smoothed and the cosmic rays filtered out. This smoothed sky spectrum was then subtracted from the first-pass QSO spectrum. There was a small zero point discrepancy between the "corrected" first-pass and the second-pass QSO spectra. A zero-point offset as a function of wavelength was computed by taking the difference of the first- and second-pass spectra and this offset was used to restore the zero point to the first-pass spectrum, to yield the final spectrum presented here. In the case of the z = 0.8514 system, zero flux in the saturated line cores of the Mg II transitions was recovered.
Post Thesis WorkFOS/HST data have been investigated.
See Churchill et al. (2000a)
See Churchill et al. (2000b)
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