Astronomy & Astrophysics

Table 1: Best fit parameters of EPIC spectrum models with their errors at the 90% confidence levels ( $\Delta \chi ^2=2.71$ ; corresponding to $\sigma =1.64$ for Gaussian statistics). For PN, MOS1, MOS2, the effective exposures after suppression of time intervals with high levels of flaring background are 33.2, 37.7, and 38.1 ks, and there are in the source extraction region 1264, 408, 408 counts, respectively ( $\sim$ $20\%$ of these counts come from the background).