We describe the tools and the underlying methods and principles for generating the spectral response functions for the four imaging instruments that were flown on the Hitomi x-ray astronomy satellite [Soft X-ray Spectrometer, or SXS; Soft X-ray Imager, or SXI, and two Hard X-ray Imagers, or HXI]. In essence, the spectral response function is a temporally and spatially averaged effective area and line-spread-function. For model-fitting x-ray spectra from an instrument, the spectral response function encapsulates the end-to-end physics of the entire system from telescope to detector, and also includes satellite attitude drift, exposure corrections, and in the case of the HXIs, drift in the telescope/detector alignment system. Accuracy in the construction of the spectral response functions is, therefore, critical to maximize the science return from the data.
The Hitomi (ASTRO-H) mission is the sixth Japanese x-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E > 2 keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft x-rays to gamma rays. After a successful launch on February 17, 2016, the spacecraft lost its function on March 26, 2016, but the commissioning phase for about a month provided valuable information on the onboard instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month.
Astro-H is the x-ray/gamma-ray mission led by Japan with international participation, launched on February 17, 2016. Soon after launch, Astro-H was renamed Hitomi. The payload consists of four different instruments (SXS, SXI, HXI, and SGD) that operate simultaneously to cover the energy range from 0.3 keV up to 600 keV. On March 27, 2016, JAXA lost contact with the satellite and, on April 28, they announced the cessation of the efforts to restore mission operations. Hitomi collected about one month’s worth of data with its instruments. This paper presents the analysis software and the data processing pipeline created to calibrate and analyze the Hitomi science data, along with the plan for the archive. These activities have been a collaborative effort shared between scientists and software engineers working in several institutes in Japan and United States.
The Hitomi (ASTRO-H) mission is the sixth Japanese X-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E > 2 keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft X-rays to gamma-rays. After a successful launch on 2016 February 17, the spacecraft lost its function on 2016 March 26, but the commissioning phase for about a month provided valuable information on the on-board instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month.
Astro-H (Hitomi) is an X-ray/Gamma-ray mission led by Japan with international participation, launched on February 17, 2016. The payload consists of four different instruments (SXS, SXI, HXI and SGD) that operate simultaneously to cover the energy range from 0.3 keV up to 600 keV. This paper presents the analysis software and the data processing pipeline created to calibrate and analyze the Hitomi science data along with the plan for the archive and user support. These activities have been a collaborative effort shared between scientists and software engineers working in several institutes in Japan and USA.
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions developed by the Institute of Space and Astronautical Science (ISAS), with a planned launch in 2015. The ASTRO-H mission is equipped with a suite of sensitive instruments with the highest energy resolution ever achieved at E > 3 keV and a wide energy range spanning four decades in energy from soft X-rays to gamma-rays. The simultaneous broad band pass, coupled with the high spectral resolution of ΔE ≤ 7 eV of the micro-calorimeter, will enable a wide variety of important science themes to be pursued. ASTRO-H is expected to provide breakthrough results in scientific areas as diverse as the large-scale structure of the Universe and its evolution, the behavior of matter in the gravitational strong field regime, the physical conditions in sites of cosmic-ray acceleration, and the distribution of dark matter in galaxy clusters at different redshifts.
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated
by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the highenergy
universe via a suite of four instruments, covering a very wide energy range, from 0.3 keV to 600 keV.
These instruments include a high-resolution, high-throughput spectrometer sensitive over 0.3–12 keV with
high spectral resolution of ΔE ≦ 7 eV, enabled by a micro-calorimeter array located in the focal plane of
thin-foil X-ray optics; hard X-ray imaging spectrometers covering 5–80 keV, located in the focal plane of
multilayer-coated, focusing hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4–12 keV,
with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and a non-focusing Compton-camera
type soft gamma-ray detector, sensitive in the 40–600 keV band. The simultaneous broad bandpass, coupled
with high spectral resolution, will enable the pursuit of a wide variety of important science themes.
The Swift gamma-ray burst explorer was launched on Nov. 20, 2004 from Cape Canaveral, Florida. The first
instrument onboard became fully operational less than a month later. Since that time the Burst Alert Telescope
(BAT) on Swift has detected more than one hundred gamma-ray bursts (GRBs), most of which have also been
observed within two minutes by the Swift narrow-field instruments: the X-Ray Telescope (XRT) and the Ultra-
Violet and Optical Telescope (UVOT). Swift trigger notices are distributed worldwide within seconds of the
trigger through the Gamma-ray burst Coordinates Network (GCN) and a substantial fraction of GRBs have
been followed up by ground and space-based telescopes, ranging in wavelength from radio to TeV. Results have
included the first rapid localization of a short GRB and further validation of the theory that short and long
bursts have different origins; detailed observations of the power-law decay of burst afterglows leading to an
improved understanding of the fireball and afterglow models; and detection of the most distant GRB ever found.
Swift is also a sensitive X-ray observatory with capabilities to monitor galactic and extragalactic transients on a
daily basis, carry out the first all-sky hard X-ray survey since HEAO-1, and study in detail the spectra of X-ray
As technological and scientific path-finder towards future observatory missions, a balloon-born hard X-ray imaging observation experiment InFOCμS has been developed. The payload has flown four times since 2000. In its 2004 Fall flight campaign InFOCμS successfully achieved first scientific observations of multiple astronomical objects from galactic compacts to cluster of galaxies. Significant signal has been detected from bright galactic objects while analysis of extragalactic objects is underway. InFOCμS plans additional and upgraded telescope-detector system as early as 2006. High energy telescope for nuclear gamma-ray line observations is under planning.
InFOCμS is a new generation balloon-borne hard X-ray telescope with focusing optics and spectroscopy in a collaboration between NASA's GSFC and Nagoya University. We had a successful 22.5-hour flight from Fort Sumner, NM on September 16-17, 2004. The InFOCμS hard X-ray telescope consists of a depth-graded platinum-carbon multilayer mirror and a CdZnTe detector, which is a pixellated solid-state device capable of imaging spectroscopy. In this paper, we present the performance of the InFOCμS CdZnTe detector. The detector is configured with a 12 × 12 segmented array of detector pixels. The pixels are 2 mm square, and are placed on 2.1 mm centers. The averaged energy resolution is 4.4 keV at 60 keV and its standard deviation is 0.36 keV over 128 pixels. It has a <sup>241</sup>Am tagged source to monitor the energy gain of each detector pixel during the flight. The gain was stable within a few percent during observations. The detector is also surrounded by a 3-cm thick CsI anti-coincidence shield to reduce background from particles and photons not incident along the mirror focal direction. Owing to the active shield, 97.3% of the background was rejected as vetoed events. The observed background rate is 2.9 × 10<sup>-4</sup> cts sec<sup>-1</sup> cm<sup>-2</sup> keV<sup>-1</sup> (20-50 keV). We achieved sensitivity as great as 5 × 10-6 cts sec<sup>-1</sup> cm<sup>-2</sup> keV<sup>-1</sup> with 8-hour observations (in 20-50 keV and three sigma detection) in this flight. We also present our plan for the future InFOCμS flights as well as their sensitivity we would expect.
Hard X-ray focusing observation is important to reveal non-thermal
emission mechanism and origin in active galaxies and clusters of
galaxies. We have carried out the hard X-ray observation throughout
the ¥infocus program, which is an international balloon-borne
experiment in collaboration with NASA/GSFC and Nagoya University.
The telescope is conical approximation of Wolter-I optics with 8 m
focal length and 40 cm diameter. It consists of 255 nested thin (0.17
mm thickness) reflectors with incidence angles of 0.10° to
0.36°. Reflectors are coated with depth-graded platinum-carbon (Pt/C) multilayers, so-called supermirrors, with periodic length of 2.6 to 13 nm and bi-layer number of 28 to 79, depending on incidence angles. We are now continuously fabricating advanced next hard X-ray telescope for the second ¥infocus flight in 2004. Compared with the first telescope, the following improvements have been made on the second one. Supermirror reflectors have wider sensitivity in energy band of 20-60 keV adopting optimum supermirror design for balloon
observation, and smaller interfacial roughness owing to complete
replication technique. For upgrading of the image quality, we then
adopted stiffer reflector substrate, selected replication mandrel with
better shape, and the modified telescope housing with higher alignment
accuracy for reflectors. The performance of the new hard X-ray
telescope was measured in X-ray beamline facility in ISAS/JAXA and
synchrotron radiation facility SPring-8. The effective area and image
quality are obtained to be 45 cm<sup>2</sup> at 30 keV and 23 cm<sup>2</sup> at 40 keV, and 2.5 arcmin in half power diameter, respectively. In this paper we report our development of the upgraded hard X-ray telescope for the second balloon flight experiment.
In addition to providing the initial gamma-ray burst trigger and location, the Swift Burst Alert Telescope (BAT) will also perform an all-sky hard x-ray survey based on serendipitous pointings resulting from the study of gamma-ray bursts. BAT was designed with a very wide field-of-view (FOV) so that it can observe roughly 1/7 of the sky at any time. Since gamma-ray bursts are uniformly distributed over the sky, the final BAT survey coverage is expected to be nearly uniform. BAT's large effective area and long sky exposures will produce a 15 - 150 keV survey with up to 30 times better sensitivity than any previous hard x-ray survey (e.g. HEAO A4). Since the sensitivity of deep exposures in this energy range is systematics limited, the ultimate survey sensitivity depends on the relative sizes of the statistical and systematic errors in the data. Many careful calibration experiments were performed at NASA/Goddard Space Flight Center to better understand the BAT instrument's response to 15-150 keV gamma-rays incident from any direction within the FOV. Using radioactive sources of gamma-rays with known locations and energies, the Swift team can identify potential systematic errors in the telescope's performance and estimate the actual Swift hard x-ray survey sensitivity in flight. These calibration results will be discussed and a preliminary parameterization of the BAT instrument response will be presented. While the details of the individual BAT CZT detector response will be presented elsewhere in these proceedings, this talk will focus on the translation of the calibration experimental data into overall hard x-ray survey sensitivity.
The properties of 32k CdZnTe detectors have been studied in the
pre-flight calibration of Burst Alert Telescope (BAT) on-board the
Swift Gamma-ray Burst Explorer (scheduled for launch in January 2004).
After corrections of the linearity and the gain, the energy resolution
of summed spectrum is 7.0 keV (FWHM) at 122~keV. In order to construct
response matrices for the BAT instrument, we extracted
mobility-lifetime (μτ) products for electrons and holes in the
CdZnTe. Based on a new method applied to <sup>57</sup>Co spectra taken at different bias voltages, μτ for electrons ranges from
5.0x10<sup>-4</sup> to 1.0x10<sup>-2</sup>cm<sup>2</sup>V<sup>-1</sup>, while μτ for holes ranges from 1.0x10<sup>-5</sup> to
1.7x10<sup>-4</sup>cm<sup>2</sup>V<sup>-1</sup>. We show that the distortion of the spectrum and the peak efficiency of the BAT instrument are well reproduced by the μτ database constructed in the calibration.
The CZT detector on the Infocus hard X-ray telescope is a pixellated
solid-state device capable of imaging spectroscopy by measuring the
position and energy of each incoming photon. The detector sits at the
focal point of an 8m focal length multilayered grazing incidence
X-ray mirror which has significant effective area between 20-40 keV.
The detector has an energy resolution of 4.0 keV at 32 keV, and the
Infocus telescope has an angular resolution of 2.2 arcminute and a
field of view of about 10 arcminutes. Infocus flew on a balloon
mission in July 2001 and observed Cygnus X-1. We present results from
laboratory testing of the detector to measure the uniformity of
response across the detector, to determine the spectral resolution,
and to perform a simple noise decomposition. We also present a hard
X-ray spectrum and image of Cygnus X-1, and measurements of the hard
X-ray CZT background obtained with the SWIN detector on Infocus.
The development of hard X-ray focusing optics is widely recognized as
one of key technologies for future X-ray observatory missions such as
NeXT(Japan), Constellation-X(US) and possibly XEUS(Europe). We have developed hard X-ray telescope employing depth-graded multilayers, so-called supermirrors. Its benefit is to reflect hard X-rays by Bragg reflection at incidence angles larger than the critical angle of total external reflection. We are now continuously fabricating platinum-carbon(Pt/C) supermirror reflectors for hard X-ray observations. In this paper we focus on our development of the
hard X-ray telescope for the first balloon flight observation
(InFOCuS) and its results. InFOCuS is an international balloon-borne hard X-ray observation experiment initiated by NASA/GSFC. InFOCuS hard X-ray telescope have been jointly developed by Nagoya University and GSFC. The telescope is conical approximation of Wolter-I optics with 8m focal length and 40cm diameter. It consists of 255 nested ultra-thin reflector pairs with incidence angles of 0.10 to 0.36deg. Reflectors are coated with Pt/C supermirrors with periodic length of 2.9 to 10nm and bi-layer number of 25 to 60, depending on incidence angles. The effective area and imaging quality are expected as 100 cm<sup>2</sup> at 30 keV and 2 arcmin in half power diameter, respectively. The InFOCuS experiment was launched on July 5, 2001, from National Scientific Balloon Facility in Texas, USA. We successfully observed Cyg X-1, chosen for a calibration target, in 20-40keV energy band. We are planning to carry out next flight for scientific observations as soon as additional telescopes, detectors, and upgraded gondola system are implemented.
Mass production of replicated thin aluminum x-ray reflecting foils for the InFOC(mu) S (International Focusing Optics Collaboration for Micro-Crab Sensitivity) balloon payload is complete, and the full mirror has been assembled. InFOC(mu) S is an 8-meter focal length hard x-ray telescope scheduled for first launch in July 2001 and will be the first instrument to focus and image x-rays at high energies (20-40 keV) using multilayer-based reflectors. The individual reflecting elements are replicated thin aluminum foils, in a conical approximation Wolter-I system similar to those built for ASCA and ASTRO-E. These previous imaging systems achieved half-power-diameters of 3.5 and 1.7-2.1 arcminutes respectively. The InFOC(mu) S mirror is expected to have angular resolution similar to the ASTRO-E mirror. The reflecting foils for InFOC(mu) S, however, utilize a vertically graded Pt/C multilayer to provide broad-band high-energy focusing. We present the results of our pre-flight characterization of the full mirror, including imaging and sensitivity evaluations. If possible, we will include imaging results from the first flight of a multilayer-based high-energy focusing telescope.
We have been developing the high throughput hard X-ray telescope, using reflectors coated with the depth graded multilayer known as supermirror, which is considered to be a key technology for future satellite hard X-ray imaging missions. InFOC(mu) $S, the International Focusing Optics Collaboration for (mu) -Crab Sensitivity is the project of the balloon observation of a cosmic hard X-ray source with this type of hard X-ray telescope and CdZnTe pixel detector as a focal plane imager. For the fist InFOC(mu) S balloon experiment, we developed the hard X-ray telescope with outermost diameter of 40cm, focal length of 8m and energy band pass of 20-40 keV, for which Pt/C multilayer was used. From the pre-flight X-ray calibration, we confirmed its energy band and imaging capability of 2 arcmin HPD and 10 arcmin FOV of FWHM, and a effective area of 50 cm<SUP>2</SUP> for 20-40 keV X-ray. We report the current status of our balloon borne experiment and performance of our hard X-ray telescope.