X-ray spectra with best-fit models. (a) Black: XMM-Newton PN spectrum, red: Chandra spectrum. (b) Black: XMM-Newton MOS2 spectrum from 2000 July 29 observation and red: XMM-Newton MOS2 spectrum from 2000 July 30 observation. (c) XMM-Newton PN spectrum. (d) XMM-Newton PN spectrum. (e) Black: XMM-Newton PN spectrum and red: Chandra spectrum. (f) XMM-Newton PN spectrum. (g) Black: XMM-Newton PN spectrum, red: Chandra spectrum from 2001 observation, and green: Chandra spectrum from 2002 observation. (h) Black: Chandra spectrum. (i) Black: XMM-Newton PN spectrum from 2002 December observation and red: XMM-Newton PN spectrum from 2002 July observation. (j) Chandra spectrum. (k) Chandra spectrum. (l) Chandra spectrum. (m) Black: XMM-Newton PN spectrum from 2001 observation and red: XMM-Newton PN spectrum from 2004 observation. (n) XMM-Newton PN spectrum. (o) Chandra spectrum. (p) Black: Chandra spectrum from 2000 observation, red: Chandra spectrum from 2001 observation, and green: Chandra spectrum from 2003 observation. (q) Chandra spectrum. (r) Black: XMM-Newton PN spectrum and red: Chandra spectrum. (s) Black: XMM-Newton PN spectrum from 2004 July 11 observation, red: XMM-Newton PN spectrum from 2001 February 2 observation, green: XMM-Newton PN spectrum from 2004 July 14 observation, blue: XMM-Newton PN spectrum from 2004 July 22 observation. (t) Black: XMM-Newton PN spectrum from 2001 observation, red: XMM-Newton PN spectrum from 2004 August observation, green: XMM-Newton PN spectrum from 2008 observation, and blue: XMM-Newton PN spectrum from 2009 observation. (u) Chandra spectrum. (v) Black: XMM-Newton PN spectrum from 2002 observation, red: XMM-Newton PN spectrum from 2003 observation, green: XMM-Newton MOS1 spectrum from 2005 January observation, blue: Chandra spectrum. (w) XMM-Newton PN spectrum. (x) Chandra spectrum. (y) Chandra spectrum. (z) Black: XMM-Newton PN spectrum from 2007 observation, red: XMM-Newton PN spectrum from 2004 observation, and green: XMM-Newton PN spectrum from 2002 observation. (aa) Black: XMM-Newton PN spectrum from 2005 observation and red: XMM-Newton PN spectrum from 2001 observation. (ab) Black: Chandra spectrum from 2006 October 14 observation and red: Chandra spectrum from 2006 October 15 observation. (ac) XMM-Newton PN spectrum.