Ground-based x-ray calibration of the Astro-H soft x-ray telescopes

Abstract

The X-ray astronomy satellite Astro-H, planed to be launched in 2015, will have several instruments for covering a wide energy band from a few hundreds eV to 600 keV. There are four X-ray telescopes, and two of them are soft X-ray telescopes (SXTs) covering up to about 15 keV. One is for an X-ray micro-calorimeter detector (SXS) and the other is for an X-ray CCD detector (SXI). The design of the SXTs is a conical approximation of the Wolter Type-I optics, which is also adopted for the telescopes on the previous mission Suzaku launched in 2005. It consists 203 thin-foil reflectors coated with gold monolayer (2000Å) on the aluminum substrate (101.6 mm length) with the thickness of 0.15, 0.23 and 0.31 mm. These are nested confocally within the radius of 58 to 225 mm. The focal length of SXTs is 5.6 m. The weight is as light as ∼ 43 kg per telescope.We present the current status of the calibration activity of two SXTs (SXT-1 and SXT-2). The developments of two SXTs were completed by NASA's Goddard Space Flight Center (GSFC). First X-ray measurements with a diverging beam at the GSFC 100m beamline found an angular resolution at 8.0 keV to be 1.1 and 1.0 arcmin (HPD) for SXT-1 and SXT-2, respectively. The full characterization of the X-ray performance has been now continuously calibrated with the 30m X-ray beamline facility at the Institute of Space and Astronautical Science (ISAS) of Japan Aerospace eXploration Agency (JAXA) in Japan. We adopted a raster scan method with a narrow X-ray pencil beam with the divergence of ∼ 15". X-ray characterization of the two SXTs has been measured from May and December 2013, respectively.In the case of SXT-1, the on-axis effective area was approximately 580, 445, 370, 270, 185 and 90 cm 2 at energies of 1. 5, 4.5, 8.0, 9.4, 11.1 and 12.9 keV respectively. The effective area of SXT-2 is 2% larger than that of SXT-1 irrespective to X-ray energy. The on-axis angular resolution of SXT-1 was evaluated as 1.3 -1.5 arcmin (HPD) in the 1.5 -13 keV band. The resolution was slightly got worse at higher energies by ∼ 0.3 arcmin. Otherwise, the resolution of SXT-2 is 1.2 arcmin, almost irrespective to X-ray energy. The field of view (FOV) was ∼ 16 arcmin at 1.5 keV, decreasing with increasing X-ray energy, and became ∼ 8 arcmin at 13 keV. The FOV is defined here as the full-width at half-maximum (FWHM) of the vignetting curve.The X-ray performance of SXT-1 and SXT-2 meets the system requirements. Because all the parameters of the SXT-2 is slightly better that of SXT-1, we adopted the SXT-2 telescope for the SXS detector of the Astro-H primary instrument with the narrow FOV.

Detail plans and preparations for the science operations of the XRISM mission

“…As a result, there were no delays in the schedule of software preparation and no delay in the release of tools and the calibration database. The products were well calibrated using instrument-specific methods, [12][13][14][15][16][17][18][19][20][21] because all the algorithms were imported into the analysis software and the latest calibration information was quickly released in the database. 5 2d-Hitomi − : In order to achieve 2c-Hitomi + , there were many interactions among the software and calibration team, instrument teams, and operation teams, which were spread across multiple agencies.…”

The Hitomi (ASTRO-H) Soft X-ray Telescope (SXT): current status of calibration

“…In order to model the effective-area curve in the edge bands, the reflectivity of the SXT's gold surface with a precise energy pitch should be measured, on which we focus in this paper. Other issues are, and will be, separately addressed in our companion papers, such as Iizuka R. et al, 3 Sato T. et al, 10 Sato T. et al in this volume, 11 Kurashima S. et al in this volume, 7 Hayashi, T. et al in this volume, 1 and Okajima, T. et al in this volume. 9 The energy resolution of the focal plane detector SXS-XCS of the ASTRO-H SXT-S is as good as ∼5 eV at 6 keV, which corresponds to the resolution power of ∼ 1000.…”

Upgrade of the 30-m x-ray pencil beam line at the Institute of Space and Astronautical Science

“…However, we note that a wider beam has a larger divergent, which leads to the vignetting effect in the beam-irradiated area. Figure 8 shows images of SXT-I 11,12 (coupled with the soft xray imager of the ASTRO-H), and panels (a) and (b) which were acquired with the nominal focal length and the corrected focal length. The 2 × 2 mm 2 beam was used for the measurement of the nominal focal length, considering defocusing proportional to the beam size and measuring time.…”