The X-Ray Telescope onboard Suzaku

Abstract

We present the design parameters, production process, and in-flight performance of the X-ray telescope (XRT) onboard Suzaku. The imaging capability is significantly improved over the ASCA XRT, which had half-power diameters of ${3\rlap {.}{}^{\mathrm {\prime }}6}$, to ${1\rlap {.}{}^{\mathrm {\prime }}8}$–${2\rlap {.}{}^{\mathrm {\prime }}3}$ for all four XRT-I modules. The optical axes are found to be distributed within a radius of ${1\rlap {.}{}^{\mathrm {\prime }}3}$, which makes the observation efficiency of all the XRTs more than 97% at the XIS-default observing position. The vignetting over the XIS field of view predicted via ray-tracing coincides with that measured for observations of the Crab Nebula to within $\sim 10\%$. Contemporaneous fits of a power law to all of 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 and Seward (1974, AJ, 79, 995) to within $\sim 2\%$. 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.

Studies of the moisture absorption of thin carbon fiber reinforced plastic substrates for x-ray mirrors

“…3 These telescopes have high angular resolution of several or sub arc seconds, but they require a large diameter to have a large effective area because the thick substrate causes a dead area in the mirror. On the other hand, mirrors with large effective areas are formed by nested thin substrates made of aluminum foil and are mounted on Japanese x-ray observatories, such as ASCA, 4 Suzaku, 5 and ASTRO-H. 6,7 These telescopes have higher collecting area to weight ratios than other x-ray telescope designs, but the angular resolution of the telescopes is limited to ∼1 arc min. This limitation is caused, in part, by the approximate conical shape of the Wolter-I optics (paraboloid and hyperboloid), the positional error between the two stage mirrors, and deformation of the substrate itself.…”

Next generation astronomical x-ray optics: high angular resolution, light weight, and low production cost

“…Suzaku [6] and NuSTAR [7] represent the state of the art oflightweight x-ray telescope making. They have angular resolutions of approximately 120 and 60 are-seconds, respectively.…”

Thin Shell, Segmented X-Ray Mirrors

“…Thus there was a premium on the effective areato-mass ratio of the X-ray mirrors, a situation for which foil mirrors provide the best solution. ASCA incorporated four identical coaligned foil mirrors, each with a mass of 10 kg [7]. Two mirrors illuminated imaging gas scintillation proportional counters, the other two illuminated the first CCD detectors ever used in an orbiting X-ray observatory.…”

“…To recover from this setback, a nearly identical Astro-E2 spacecraft was built. The foil mirrors are largely identical in design and construction to those of Astro-E [16]. The single major change was the addition of a stray light baffle, which was attached to the front of each mirror to largely eliminate the paths to the focal plane of radiation reflected only off the secondary reflector [17].…”