/ftp/cats/aliases/B/BGK2008



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J/MNRAS/388/849     NGC253 XMM observations                  (Barnard+, 2008)
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	tablea1.dat tablea2.dat
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Query from: http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=J/MNRAS/388/849
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Beginning of ReadMe : J/MNRAS/388/849 NGC253 XMM observations (Barnard+, 2008) ================================================================================ A multi-coloured survey of NGC253 with XMM-Newton: testing the methods used for creating luminosity functions from low-count data. Barnard R., Greening L.S., Kolb U. <Mon. Not. R. Astron. Soc., 388, 849-862 (2008)> =2008MNRAS.388..849B ================================================================================ ADC_Keywords: Galaxies, nearby ; X-ray sources Keywords: galaxies: individual: NGC 253 - X-rays: binaries - X-rays: general Abstract: NGC 253 is a local, starbursting spiral galaxy with strong X-ray emission from hot gas, as well as many point sources. We have conducted a spectral survey of the X-ray population of NGC 253 using a deep XMM-Newton observation. NGC 253 only accounts for  20 per cent of the XMM-Newton EPIC field of view, allowing us to identify  100 X-ray sources that are unlikely to be associated with NGC 253. Hence, we were able to make a direct estimate of contamination from, for example, foreground stars and background galaxies. X-ray luminosity functions (XLFs) of galaxy populations are often used to characterize their properties. There are several methods for estimating the luminosities of X-ray sources with few photons. We have obtained spectral fits for the brightest 140 sources in the 2003 XMM-Newton observation of NGC 253, and compare the best-fitting luminosities of those 69 non-nuclear sources associated with NGC 253 with luminosities derived using other methods. We find the luminosities obtained from these various methods to vary systematically by a factor of up to 3 for the same data; this is largely due to differences in absorption. We therefore conclude that assuming Galactic absorption is probably unwise; rather, one should measure the absorption for the population. Description: XMM-Newton observations are susceptible to periods of high background levels, caused by increased flux of solar particles. We screened the data from each of the EPIC cameras (MOS1, MOS2 and pn), to remove flaring intervals. This process resulted in  46ks of good time for the PN and  69ks for the MOS cameras.

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