Suzaku, the fifth in a series of Japanese X-ray astronomy satellites following the highly successful Hakucho,
Tenma, Ginga and ASCA satellites, was launched on July 10th, 2005. The X-ray telescope (XRT-I0 through
I3) together with the focal plane detector XIS (XIS 0 through 3 corresponding with the number of XRT-I) has
features of low background and large effective area covering an energy range from 0.2 to 12 keV. The XRTs were
manufactured mostly by a hand, so that their response function is well known very complex. In order to improve
the accuracy of the function, we have been developing a Monte-Carlo technique that simulates the X-ray event
reflected at the XRT with one photon by one photon (ray-tracing). The imaging capability, the point spread
function (PSF) or the encircled energy function (EEF), is the most complex in the response function, that varies
from telescope to telescope and ranges from 1.′8 to 2.′3 in half power diameters (HPD). We found that their
variations are primarily due to the difference of their focal length. We then tuned the focal length and found
that the PSF or EEF was better reproduced when the variations of -50 −+50 mm are given to the focal length
of 4750 mm.
We report a new type X-ray imaging polarimeter: a multilayer-coated CCD. When the X-rays are detected by the CCD,
with the incident angle of 45 deg, through the coated multi-layer, the transmissions of the P and S polarized photons are
different from each other and we can get an image with a selected position angle of the polarization.
By the simulation of the transmission of the multi-layer, we designed an optimal number of the layer-pair and their
thickness. The target wave length is 135Å, because the Mo/Si multi-layer has a good performance in this energy range.
If the dead layer of the back-side CCD is 1000Å, nine layer-pairs make the largest difference between the P and S
We deposited the Mo/Si multi-layer directly on a back-side CCD. The CCD was exposed to the polarized photons from
synchrotron radiation with 45 deg incident angle. The detected intensity is measured as a function of the photon energy
and of the rotation angle around the photon beam. The detection of the polarization is confirmed. However the
measured performance is lower than expected. Some possibilities of the cause are discussed.
We present X-ray characteristics of X-ray telescopes (XRTs) onboard the Astro-E2 satellite. It is scheduled to be launched in February 2005. We have been performed X-ray characterization measurements of XRTs at Institute of Space and Astronautical Science (ISAS) since January 2003. We adopted a raster scan method with a narrow X-ray pencil beam. Angular resolution of the Quadrants composed of the Astro-E2 XRT was evaluated to be 1'.6-2'.2 (HPD; Half Power Diameter), irrespective of the X-ray energy, while those of the Astro-E XRT was 2'.0-2'.2. The effective area of a telescope is approximately 450, 330, 250, and 170 [cm2] at energies of 1.49, 4.51, 8.04, and 9.44 keV, respectively. The field of view (FOV) of the XRTs which is defined as Full Width Half Maximum (FWHM) of the vignetting function is ≈18' at 4.51 keV. We summarize these characters of the XRTs.
We report a ground-based X-ray calibration of the Astro-E2 X-ray
telescope at the PANTER test facility. Astro-E2, to be launched in
February 2005, has five X-Ray Telescopes (XRTs). Four of them focus on
the X-Ray Imaging Spectrometers (XIS) while the other on the X-Ray
Spectrometer (XRS). They are designed with a conical approximation of
Wolter-I type optics, nested with thin foil mirrors to enhance their
throughput. A calibration test of the first Astro-E2 flight XRT for
XIS was carried out at the PANTER facility in August 2003. This
facility has an 130 meter long diverging beam from X-ray generator to
XRT. Owing to the small X-ray spot size of about 2 mm dia., we verified that the focal position of each quadrant unit converged within 10 arcsec. The energy band around Au-M edge structures was
scanned with a graphite crystal. The edge energy (Au M5) is consistent with that listed in Henke et al. 1997. Owing to the large area coverage of the PSPC detector which is a spare of the ROSAT satellite, off-axis images including stray lights at large off-axis angle (up to 6 degree) were obtained with a large field of view. We also compared the results with those measured with the parallel pencil beam at ISAS which is in detail reported in our companion paper by Itoh A. et al..
Astro-E2, to be launched in early 2005, will carry five X-ray Telescopes (XRT). The design of the XRT is the same as the previous original mission Astro-E, that is a conical approximation of Wolter Type-I optics, where about 170 thin-foil reflectors are nested confocally. Some modifications from Astro-E are adopted within the severe constraints due to the policy of "re-build" instruments. One of the major changes is the addition of pre-collimators for the stray light protection. Several modifications on the fabrication processes are also made. The replication glass mandrels are screened carefully, which is expected to reduce the figure error of replicated reflectors. We thus expect better performance than Astro-E especially in imaging capability. In order to qualify the performance of the Astro-E2 XRT, we have started ground calibration program of XRT at 30 meter X-ray beam facility of the Institute of Space and Astronautical Science (ISAS). We have found positive improvements on the telescope performance from the Astro-E, which probably arise from the applied modifications. The on-axis half-power diameter (HPD) has been evaluated to be 1.6-1.7 arcmin, which is improved from the Astro-E (2.0 ~ 2.1 arcmin HPD). The on-axis effective areas of quadrants are larger than the average of Astro-E by about 5%. The on-axis effective areas of the XRT for X-ray Imaging Spectrometers (XIS) are approximately 460, 340, 260, and 190 cm2 at energies of 1.49, 4.51, 8.04, and 9.44 keV, respectively. The present paper describes the recent results of
the performance of the first flight assembly of the Astro-E2 XRT.