On-orbit performance of the X-ray telescopes and thermal wobbling of the Suzaku satellite

We present the in-flight performance of the X-ray telescopes (XRTs) onboard Suzaku. The imaging capability is significantly improved over the ASCA XRT, which had half-power diameters of 3′.6, to 1′.8-2′.3 for all four XRT-I modules. Contemporaneous fits of a power law to all the XIS spectra of the Crab Nebula taken at the two standard observing positions (XIS/HXD-default positions) gives a flux consistent with that obtained by Toor & Seward (1974) to within ∼2%. The pre-collimator on the top of each XRT module successfully reduces the intensity of the stray light from the 20′ and 50′-off directions down to the level of pre-flight expectations. We also present the thermal wobbling of the satellite. The wobbling causes the alignment error between the XRT-XIS system and the attitude and orbit control system. The wobbling of the alignment is as large as ∼ larcmin. In the currently processed data, the absolute coordinate also has systematic uncertainty of up to ∼ larcmin.