XMM-Newton Data Extraction

Figure 1: Lightcurves from the EPIC-pn (blue line) and RXTE-PCA (red line).

Our observation covered most of XMM-Newton's orbit 108, on 2000 June 11/12, and was quasi-simultaneous with the Rossi X-ray Timing Explorer (RXTE). Here, we mainly report on data from the European Photon Imaging pn-camera onboard XMM-Newton (EPIC, Strüder et al., 2001, Turner et al., 2001), which was operated in its small window mode and the medium thick filter. The EPIC MOS-1 and MOS-2 cameras were operated in the timing mode and the full-frame mode, respectively. Due to remaining calibration uncertainties of these cameras, we concentrate on the results from the EPIC-pn in this paper, and use the MOS-2 data only to check the instrument independency of our results. The data analysis was performed with version 5.3 of the XMM-Newton Science Analysis System (SAS) and with version 11.2.0 of XSPEC (Arnaud, 1996).

The source spectra and lightcurves were obtained from a circle with $40''$ radius centered on the source. We extracted spectra from single and double events separately, i.e., from events where all electrons produced by an X-ray photon are detected in a single EPIC-pn pixel or in two adjacent EPIC-pn pixels, respectively. As the energy-dependent distribution differs for single and for double events, modeling the data from both types of events separately allows us to check for the possible presence of pile-up in our data. Background data were extracted from a circle of the same area as the source data, but on a different position of the EPIC-pn to avoid the possible contamination of the background spectrum by out of time events, i.e., by photons registered during the read-out cycle of the EPIC pn. Since the background increases during the final part of the observation as XMM-Newton approaches the Earth's radiation belts, the last 20ksec of our observation are unusable. Furthermore, the telemetry gap due to the incomplete ground station coverage of XMM-Newton's orbit during the early phase of the mission is still present in our data (this situation has changed since then). The total EPIC-pn exposure time after the background screening is 112ksec (with a ``live-time'' of 65ksec).

The blue line in Figure 1 shows the 2-10keV EPIC-pn lightcurve of MCG$-$6-30-15 for our observation. Since the source is strongly variable, in this paper we analyze data from both the overall observation, and from 10ksec long data segments.