XRISM (X-ray Imaging and Spectroscopy Mission) is an X-ray astronomy satellite developed in collaboration with JAXA, NASA and ESA. It successfully launched on Sept. 7, 2023. Two complementary X-ray telescopes, Resolve and Xtend are on-board XRISM. Resolve uses the pixelized X-ray micro calorimeter developed by NASA/GSFC and has very high energy resolution of 5 eV. On the other hand, Xtend uses an X-ray CCD camera as its focal plane detector which has high spatial resolution and a wide field of view. We evaluated the performance of the X-ray Mirror Assembly (XMA) for Xtend using data observed during the commissioning and PV phases of XRISM. To verify the imaging performance, the Point Spread Functions (PSF) generated from the observations of NGC 4151 and PDS 456 were compared with the ground-calibration results. The results show that the imaging performance of Xtend-XMA is not significantly different from that of the ground calibration, and that it meet the requirement. The effective area was verified by comparing the results of simultaneous observations of 3C 273 by XRISM and four X-ray astronomy satellites (Chandra, XMM-Newton, NuSTAR, and Swift). The results of the fitting of the X-ray spectrum of Xtend show no significant difference from the results of other satellites, suggesting the effective area used for fitting is correct. The on-axis position on the detector was estimated from the intensity of the Abell 2029 observations at four off-axis angles. The on-axis is about 40 arcsec away from the aim point, and the decrease in effective area at the aim point is less than 1%. Stray light observations of the Crab Nebula at 60 arcmin off-axis were obtained at two different satellite roll angles. The stray light intensity obtained at each roll angle was significantly different, verifying the dependence of the stray light on the roll angle.
XRISM (X-Ray Imaging and Spectroscopy Mission) is an astronomical satellite with the capability of highresolution spectroscopy with the X-ray microcalorimeter, Resolve, and wide field-of-view imaging with the CCD camera, Xtend. The Xtend consists of the mirror assembly (XMA: X-ray Mirror Assembly) and detector (SXI: Soft X-ray Imager). The components of SXI include CCDs, analog and digital electronics, and a mechanical cooler. After the successful launch on September 6th, 2023 (UT) and subsequent critical operations, the mission instruments were turned on and set up. The CCDs have been kept at the designed operating temperature of −110°C after the electronics and cooling system were successfully set up. During the initial operation phase, which continued for more than a month after the critical operations, we verified the observation procedure, stability of the cooling system, all the observation options with different imaging areas and/or timing resolutions, and operations for protection against South Atlantic Anomaly. We optimized the operation procedure and observation parameters including the cooler settings, imaging areas for the specific modes with higher timing resolutions, and event selection algorithm. We summarize our policy and procedure of the initial operations for SXI. We also report on a couple of issues we faced during the initial operations and lessons learned from them.
HiZ-GUNDAM is a future satellite mission whose mission concept was approved by ISAS/JAXA, and it is one of the future satellite candidates of JAXA’s competitive medium-class mission. HiZ-GUNDAM will lead time-domain astronomy in 2030s, and its key sciences are (1) exploration of the early universe with high-redshift gamma-ray bursts, and (2) contribution to the multi-messenger astronomy. Two mission payloads are aboard HiZ-GUNDAM to realize these two scientific issues. The wide field X-ray monitors which consist of Lobster Eye optics array and focal imaging sensor, monitor ~0.5 steradian field of view in 0.5–4 keV energy range. The near infrared telescope with an aperture size of 30 cm in diameter performs simultaneous 5-band photometric observation in 0.5–2.5 μm wavelength with Koester’s prism for X-ray transients discovered by Wide Field X-ray Monitor. In this paper, we introduce the mission overview of HiZ-GUNDAM while the information contained herein may change in future studies.
The X-Ray Imaging and Spectroscopy Mission (XRISM) project at JAXA officially started in 2018. Following the development of onboard components, the proto-flight test was conducted from 2021 to 2023 at JAXA Tsukuba Space Center. The spacecraft was launched from JAXA Tanegashima Space Center on September 7, 2023 (JST), and onboard components, including the science instruments, were activated during the in-orbit commissioning phase. Following the previous report in 2020, we report the spacecraft ground tests, the launch operation, in-orbit operations, and the status and plan of initial and subsequent guest observations.
Xtend is one of the two telescopes onboard the X-ray imaging and spectroscopy mission (XRISM), which was launched on September 7th, 2023. Xtend comprises the Soft X-ray Imager (SXI), an X-ray CCD camera, and the X-ray Mirror Assembly (XMA), a thin-foil-nested conically approximated Wolter-I optics. A large field of view of 38′ × 38′ over the energy range from 0.4 to 13 keV is realized by the combination of the SXI and XMA with a focal length of 5.6 m. The SXI employs four P-channel, back-illuminated type CCDs with a thick depletion layer of 200 μm. The four CCD chips are arranged in a 2×2 grid and cooled down to −110°C with a single-stage Stirling cooler. Before the launch of XRISM, we conducted a month-long spacecraft thermal vacuum test. The performance verification of the SXI was successfully carried out in a course of multiple thermal cycles of the spacecraft. About a month after the launch of XRISM, the SXI was carefully activated and the soundness of its functionality was checked by a step-by-step process. Commissioning observations followed the initial operation. We here present pre- and post-launch results verifying the Xtend performance. All the in-orbit performances are consistent with those measured on ground and satisfy the mission requirement. Extensive calibration studies are ongoing.
The solar neutron and gamma-ray spectroscopy (SONGS) mission is a 3U CubeSat dedicated for detecting neutrons and gamma-rays associated with intense solar flares. Solar neutron observations have not been in progress because ground-based observations are affected by attenuation in the Earth's atmosphere, and there is no dedicated mission in space at present. Hence, we are now developing in collaboration between science and engineering people at universities, and preparing for launch around 2024 during the next solar maximum. The SONGS carries a novel radiation detector which consists of multi-layered plastic scintillator bars and GAGG(Ce) scintillator array so that it can determine energies for both neutrons and gamma-rays. In total 704 signals from silicon photo-multipliers (SiPMs) are processed by 45 ASICs with very low power consumption, and realized within limited resources. In this presentation, we will describe scientific motivation, mission and instrument overview, and results from the bread-board model (BBM).
Xtend is a soft x-ray imaging telescope developed for the x-ray imaging and spectroscopy mission (XRISM). XRISM is scheduled to be launched in the Japanese fiscal year 2022. Xtend consists of the soft x-ray imager (SXI), an x-ray CCD camera, and the x-ray mirror assembly (XMA), a thin-foil-nested conically approximated Wolter-I optics. The SXI uses the P-channel, back-illuminated type CCD with an imaging area size of 31mm on a side. The four CCD chips are arranged in a 2×2 grid and can be cooled down to −120 °C with a single-stage Stirling cooler. The XMA nests thin aluminum foils coated with gold in a confocal way with an outer diameter of 45 cm. A pre-collimator is installed in front of the x-ray mirror for the reduction of the stray light. Combining the SXI and XMA with a focal length of 5.6m, a field of view of 38′ × 38′ over the energy range from 0.4 to 13 keV is realized. We have completed the fabrication of the flight model of both SXI and XMA. The performance verification has been successfully conducted in a series of sub-system level tests. We also carried out on-ground calibration measurements and the data analysis is ongoing.
Understanding and reducing in-orbit instrumental backgrounds are essential to achieving high sensitivity in hard x-ray astronomical observations. The observational data of the Hard X-ray Imager (HXI) onboard the Hitomi satellite provide useful information on the background components due to its multilayer configuration with different atomic numbers: the HXI consists of a stack of four layers of Si (Z = 14) detectors and one layer of cadmium telluride (CdTe) (Z = 48, 52) detector surrounded by well-type Bi4Ge3O12 active shields. Based on the observational data, the backgrounds of the top Si layer, the three underlying Si layers, and the CdTe layer are inferred to be dominated by different components, namely, low-energy electrons, albedo neutrons, and proton-induced radioactivation, respectively. Monte Carlo simulations of the in-orbit background of the HXI reproduce the observed background spectrum of each layer well, thereby quantitatively verifying the above hypothesis. In addition, we suggest the inclusion of an electron shield to reduce the background.
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