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.
The Large Size Telescopes, LSTs, located at the center of the Cherenkov Telescope Array, CTA, will be sensitive
for low energy gamma-rays. The camera on the LST focal plane is optimized to detect low energy events based
on a high photon detection efficiency and high speed electronics. Also the trigger system is designed to detect
low energy showers as much as possible. In addition, the camera is required to work stably without maintenance
in a few tens of years. In this contribution we present the design of the camera for the first LST and the status
of its development and production.
WF-MAXI is a soft X-ray transient monitor proposed for the ISS/JEM. Unlike MAXI, it will always cover a large field of view (20 % of the entire sky) to detect short transients more efficiently. In addition to the various transient sources seen by MAXI, we hope to localize X-ray counterparts of gravitational wave events, expected to be directly detected by Advanced-LIGO, Virgo and KAGRA in late 2010's. The main instrument, the Soft X-ray Large Solid Angle Cameras (SLC) is sensitive in the 0.7-12 keV band with a localization accuracy of ~ 0:1°. The Hard X-ray Monitor (HXM) covers the same sky field in the 20 keV-1 MeV band.
WF-MAXI is a mission to detect and localize X-ray transients with short-term variability as gravitational-wave (GW) candidates including gamma-ray bursts, supernovae etc. We are planning on starting observations by WF-MAXI to be ready for the initial operation of the next generation GW telescopes (e.g., KAGRA, Advanced LIGO etc.). WF-MAXI consists of two main instruments, Soft X-ray Large Solid Angle Camera (SLC) and Hard X-ray Monitor (HXM) which totally cover 0.7 keV to 1 MeV band. HXM is a multi-channel array of crystal scintillators coupled with APDs observing photons in the hard X-ray band with an effective area of above 100 cm<sup>2</sup>. We have developed an analog application specific integrated circuit (ASIC) dedicated for the readout of 32-channel APDs' signals using 0.35 μm CMOS technology based on Open IP project and an analog amplifier was designed to achieve a low-noise readout. The developed ASIC showed a low-noise performance of 2080 e<sup>-</sup> + 2.3 e<sup>-</sup>/pF at root mean square and with a reverse-type APD coupled to a Ce:GAGG crystal a good FWHM energy resolution of 6.9% for 662 keV -rays.
Wide-Field MAXI (WF-MAXI) planned to be installed in Japanese Experiment Module “Kibo” Exposed Facility of the international space station (ISS). WF-MAXI consists of two types of cameras, Soft X-ray Large Solid Angle Camera (SLC) and Hard X-ray Monitor (HXM). HXM is multi-channel arrays of CsI scintillators coupled with avalanche photodiodes (APDs) which covers the energy range of 20 - 200 keV. SLC is arrays of CCD, which is evolved version of MAXI/SSC. Instead of slit and collimator in SSC, SLC is equipped with coded mask allowing its field of view to 20% of all sky at any given time, and its location determination accuracy to few arcminutes. In older to achieve larger effective area, the number of CCD chip and the size of each chip will be larger than that of SSC. We are planning to use 59 x 31 mm<sup>2</sup> CCD chip provided by Hamamatsu Photonics. Each camera will be quipped with 16 CCDs and total of 4 cameras will be installed in WF-MAXI. Since SLC utilize X-ray CCDs it must equip active cooling system for CCDs. Instead of using the peltier cooler, we use mechanical coolers that are also employed in Astro-H. In this way we can cool the CCDs down to -100C. ISS orbit around the earth in 90 minutes; therefore a point source moves 4 arcminutes per second. In order to achieve location determination accuracy, we need fast readout from CCD. The pulse heights are stacked into a single row along the vertical direction. Charge is transferred continuously, thus the spatial information along the vertical direction is lost and replaced with the precise arrival time information. Currently we are making experimental model of the camera body including the CCD and electronics for the CCDs. In this paper, we show the development status of SLC.
Monitor of All-sky X-ray Image (MAXI) is mounted on the International Space Station (ISS). Since 2009 it has been scanning the whole sky in every 92 minutes with ISS rotation. Due to high particle background at high latitude regions the carbon anodes of three GSC cameras were broken. We limit the GSC operation to low-latitude region around equator. GSC is suffering a double high background from Gamma-ray altimeter of Soyuz spacecraft. MAXI issued the 37-month catalog with 500 sources above ~0.6 mCrab in 4-10 keV. MAXI issued 133 to Astronomers Telegram and 44 to Gammaray burst Coordinated Network so far. One GSC camera had a small gas leak by a micrometeorite. Since 2013 June, the 1.4 atm Xe pressure went down to 0.6 atm in 2014 May 23. By gradually reducing the high voltage we keep using the proportional counter. SSC with X-ray CCD has detected diffuse soft X-rays in the all-sky, such as Cygnus super bubble and north polar spur, as well as it found a fast soft X-ray nova MAXI J0158-744. Although we operate CCD with charge-injection, the energy resolution is degrading. In the 4.5 years of operation MAXI discovered 6 of 12 new black holes. The long-term behaviors of these sources can be classified into two types of the outbursts, 3 Fast Rise Exponential Decay (FRED) and 3 Fast Rise and Flat Top (FRFT). The cause of types is still unknown.
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.
We are now investigating and studying a small satellite mission HiZ-GUNDAM for future observation of gamma-ray bursts (GRBs). The mission concept is to probe “the end of dark ages and the dawn of formation of astronomical objects”, i.e. the physical condition of early universe beyond the redshift z > 7. We will consider two kinds of mission payloads, (1) wide field X-ray imaging detectors for GRB discovery, and (2) a near infrared telescope with 30 cm in diameter to select the high-z GRB candidates effectively. In this paper, we explain some requirements to promote the GRB cosmology based on the past observations, and also introduce the mission concept of HiZ-GUNDAM and basic development of X-ray imaging detectors.
The Cherenkov Telescope Array (CTA) project aims to implement the world’s largest next generation of Very High Energy gamma-ray Imaging Atmospheric Cherenkov Telescopes devoted to the observation from a few tens of GeV to more than 100 TeV. To view the whole sky, two CTA sites are foreseen, one for each hemisphere. The sensitivity at the lowest energy range will be dominated by four Large Size Telescopes, LSTs, located at the center of each array and designed to achieve observations of high red-shift objects with the threshold energy of 20 GeV. The LST is optimized also for transient low energy sources, such as Gamma Ray Bursts (GRB), which require fast repositioning of the telescope. The overall design and the development status of the first LST telescope will be discussed.
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 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
high-energy universe by performing high-resolution, high-throughput spectroscopy with moderate angular
resolution. ASTRO-H covers very wide energy range from 0.3 keV to 600 keV. ASTRO-H allows a combination
of wide band X-ray spectroscopy (5-80 keV) provided by multilayer coating, focusing hard X-ray
mirrors and hard X-ray imaging detectors, and high energy-resolution soft X-ray spectroscopy (0.3-12 keV)
provided by thin-foil X-ray optics and a micro-calorimeter array. The mission will also carry an X-ray CCD
camera as a focal plane detector for a soft X-ray telescope (0.4-12 keV) and a non-focusing soft gamma-ray
detector (40-600 keV) . The micro-calorimeter system is developed by an international collaboration led
by ISAS/JAXA and NASA. The simultaneous broad bandpass, coupled with high spectral resolution of
ΔE ~7 eV provided by the micro-calorimeter will enable a wide variety of important science themes to be
MAXI, the first astronomical payload on JEM-EF of ISS, began operation on August 3, 2009 for monitoring all-sky
X-ray images every ISS orbit (92 min). All instruments as well as two main X-ray slit cameras, the GSC and SSC,
worked well as expected for one month test operation. The MAXI has been operated since August, 2009 and monitored
more than 300 X-ray sources, which include Galactic black holes and black hole candidates (BH/BHC), transient X-ray
pulsars, X-ray novae, X-ray bursts, CVns, a considerable number of AGNs and so on. Automatic nova-alert and rapid
report system is starting up, while we have published more than 30 results publicly on GCN and ATel with manual
analysis. We are also releasing daily data more than 200 targets publicly.
Now MAXI has continued steady operation since the beginning of 2010 although capability of a part of X-ray
detectors is going down from initial ability. We have obtained some remarkable results concerning BH/BHC, X-ray
pulsars and AGNs. As one of the results XTE J1752-223, an X-ray nova accompanying a black hole candidate, has
revealed an evolution of accretion disc and high energy plasma from the data for seven-month observations.
In this paper we report the operation status of MAXI on the ISS as well as early several astronomical results.
We are developing the CALorimetric Electron Telescope, CALET, mission for the Japanese Experiment Module
Exposed Facility, JEM-EF, of the International Space Station. Major scientific objectives are to search for the nearby
cosmic ray sources and dark matter by carrying out a precise measurement of the electrons in 1 GeV - 20 TeV and
gamma rays in 20 MeV - several 10 TeV. CALET has a unique capability to observe electrons and gamma rays over 1
TeV since the hadron rejection power can be larger than 10<sup>5</sup> and the energy resolution better than a few % over 100 GeV.
The detector consists of an imaging calorimeter with scintillating fibers and tungsten plates and a total absorption
calorimeter with BGO scintillators. CALET has also a capability to measure cosmic ray H, He and heavy ionsi up to
1000 TeV. It also will have a function to monitor solar activity and gamma ray transients. The phase A study has
started on a schedule of launch in 2013 by H-II Transfer Vehicle (HTV) for 5 year observation.
Monitor of All-sky X-ray Image (MAXI) is an X-ray all-sky monitor,
which will be delivered to the International Space Station (ISS)
by a space shuttle crew in early 2009,
to scan almost the entire sky once every 96 minutes for
a mission life of two to five years. The detection sensitivity will be
5 mCrab (5σlevel) for a one-day MAXI operation, 2 mCrab for one week,
and 1 mCrab for one month, reaching a source confusion limit of 0.2 mCrab in two years.
In this paper, brief descriptions are presented for the MAXI mission and payload, and
three operation phases, 1) the launch-to-docking phase, 2) the initial in-orbit calibration phase,
and 3) the routine operation phase. We also describes the MAXI data product and its release plan for public users.
MAXI (Monitor of All-sky X-ray Image) is a payload on board the International Space Station,
and will be launched on April 2009.
We report on the current development status on MAXI, in particular on the two types of X-ray camera (GSC and SSC),
and the simulation results of the MAXI observation.
SSC is a CCD camera.
The moderate energy resolution enables us to detect the various emission peak including 0.5 keV oxygen line.
The averaged energy resolution at the CCD temperature of -70 deg is 144.5 eV (FWHM) for 5.9 keV X-ray.
GSC includes proportional gas counters, which have large X-ray detection area (5350cm<sup>2</sup>).
The averaged position resolution of 1.1mm at 8 keV enable us to determined the celestial position of bright sources
within the accuracy of 0.1 degree.
The simulation study involving the results of performance test exhibits the high sensitivity of MAXI as designed.
MAXI is the first payload to be attached on JEM-EF (Kibo exposed facility) of ISS. It provides an all sky X-ray image
every ISS orbit. If MAXI scans the sky during one week, it could make a milli-Crab X-ray all sky map excluding bright
region around the sun. Thus, MAXI does not only inform X-ray novae and transients rapidly to world astronomers if
once they occur, but also observes long-term variability of Galactic and extra-Galactic X-ray sources. MAXI also
provides an X-ray source catalogue at that time with diffuse cosmic X-ray background.
MAXI consists of two kinds of detectors, position sensitive gas-proportional counters for 2-30 keV X-rays and CCD
cameras for 0.5-10 keV X-rays. All instruments of MAXI are now in final phase of pre-launching tests of their flight
modules. We are also carrying out performance tests for X-ray detectors and collimators. Data processing and analysis
software including alert system on ground are being developed by mission team.
In this paper we report an overview of final instruments of MAXI and capability of MAXI.
We propose a gamma-ray burst detector (GRB) detector combining the silicon
drift detector (SDD) array and scintillators with broadband X-ray and
gamma-ray coverage (0.5-1000 keV or more), high energy resolution (2-10%)
and high time resolution (~μs) in space. To realize such compact
high-performance detector without photomultiplier tubes, we constructed
proto-type model using KETEK SDD with a detection area of 1 cm<sup>2</sup> and BGO
crystal. Signals from both detectors are clearly separated by the double
integration method. The detector shows a very good performance. Obtained
FWHM energy resolution was 191 eV at 5.9 keV in the SDD, while 6.5% at
662 keV in the BGO at −30 degree C. Evaluation of the 7 channel SDD array and
development of analog ASIC for its readout are also presented.
Monitor of All-sky X-ray Image (MAXI) is an X-ray all-sky scanner, which will be attached on Exposed Facility of Japanese Experiment Module dubbed "Kibo" of International Space Station (ISS). MAXI will be launched by the Space Shuttle or the Japanese H-IIA Transfer Vehicle (HTV) in 2008. MAXI carries two types of X-ray cameras: Solid-state Slit Camera (SSC) for 0.5-10 keV and Gas Slit Camera (GSC) for 2-30 keV bands. Both have long narrow fields of view (FOV) made by a slit and orthogonally arranged collimator plates (slats). The FOV will sweep almost the whole sky once every 96 minutes by utilizing the orbital motion of ISS. Then the light curve of an X-ray point source become triangular shape in one transit. In this paper, we present the actual triangular response of the GSC collimator, obtained by our calibration. In fact they are deformed by gaps between the slats, leaning angle of the slats, and the effective width of the slats. We are measuring these sizes by shooting X-ray beams into the detector behind the collimator. We summarize the calibration and present the first compilation of the data to make the GSC collimator response, which will be useful for public users.
Monitor of All-sky X-ray Image(MAXI) is an X-ray all sky monitor, which will be attached to the Japanese Experiment Module (JEM) on the International Space Station (ISS) around the year 2008. MAXI carries two types of scientific instruments. The Gas Slit Camera(GSC) consists of twelve Xe filled one-dimensional position sensitive gas proportional counters sensitive to X-ray in 2-30 keV band. The Solid-state Slit Camera (SSC) is a set of X-ray CCD arrays sensitive to 0.5-10 keV photons. Both detectors are utilized in combination with a slit
and orthogonally arranged collimator plates to produce one-dimensional X-ray images along sky great circles. The instruments are now under fabrication and preflight testing. A detector response matrix (DRM) of GSC is also under development phase based on flight model calibration tests for counters and collimators. MAXI's
overall performance depends on not only hardware characteristics but on the fact that the field-of-view changes in time even during observations. To study this complicated situation, we are developing a software, DRM builder, and also a simulation software to evaluate "realistic" performance of GSC in ISS orbits.
Monitor of All-sky X-ray Image (MAXI) is an X-ray all-sky monitor,
which will be delivered to the International Space Station (ISS) in 2008, to scan almost the whole sky once every 96 minutes for a mission life of two years. The detection sensitivity will be 7~mCrab (5σ level) in one scan, and 1~mCrab for one-week accumulation. At previous SPIE meetings, we presented the development status
of the MAXI payload, in particular its X-ray detectors. In this paper, we present the whole picture of the MAXI system, including the downlink path and the MAXI ground system. We also examine the MAXI system components other than X-ray detectors from the point of view of the overall performance of the mission. The engineering model test of the MAXI X-ray slit collimator shows that we can achieve the position determination accuracy of <0.1 degrees, required for the ease of follow-up observations. Assessing the downlink paths, we currently estimates that the MAXI ground system receive more than 50% of the observational data in "real time" (with time delay of a few to ten seconds), and the rest of data with delay of 20 minutes to a few hours from detection, depending on the timing of downlink. The data will be processed in easily-utilised formats, and made open to public users through the Internet.
The NeXT mission has been proposed to study high-energy non-thermal phenomena in the universe. The high-energy response of the super mirror will enable us to perform the first sensitive imaging observations up to 80 keV. The focal plane detector, which combines a fully depleted X-ray CCD and a pixelated CdTe detector, will provide spectra and images in the wide energy range from 0.5 keV to 80 keV. In the soft gamma-ray band upto ~1 MeV, a narrow field-of-view Compton gamma-ray telescope utilizing several tens of layers of thin Si or CdTe detector will provide precise spectra with much higher sensitivity than present instruments. The continuum sensitivity will reach several x 10<sup>-8</sup> photons/s/keV/cm<sup>2</sup> in the hard X-ray region and a few x 10<sup>-7</sup> photons/s/keV/cm<sup>2</sup> in the soft gamma-ray region.
The current status is reported of the development of Monitor of All-sky X-ray Image and the measurement of its observational response. MAXI is a scanning X-ray camera to be attached to the Japanese Experiment Module of the International Space Station in 2008. MAXI is mainly composed of two kinds of instruments, GSC which is sensitive to the 2 - 30 keV photons, and SSC to the 0.5 - 10 keV ones. As an X-ray all-sky monitor, MAXI has an unprecedented sensitivity of 7 mCrab in one orbit scan, and 1 mCrab in one week. Using the engineering mode of the proportional counter and of the collimator for GSC, the observational response of GSC is extensively measured. The acceptable performances are obtained as a whole for both the collimator and the counter. The engineering models of the other part of MAXI are also constructed and the measurement of their performance is ongoing.
MAXI is an X-ray all-sky monitor which will be mounted on the Japanese Experimental Module (JEM) of the International Space Station (ISS) in 2008. The Gas Slit Camera (GSC) consists of 12 one-dimensional position sensitive proportional counters and the sensitivity will be as high as 1 mCrab for a one-week accumulation in the 2-30 keV band. In order to calibrate the detectors and electronic systems thoroughly before the launch, a fast and
versatile Ground Support Electronic (GSE) system is necessary. We have developed a new GSE based on VME I/O boards for a Linux workstation. These boards carry reconfigurable FPGAs of 100,000 gates, together with 16 Mbytes of SDRAM. As a demonstration application of using this GSE, we have tested the positional response of a GSC engineering counter. We present a schematic view of the GSE highlighting the functional design, together with a future vision of the ground testing of the GSC flight counters and digital associated processor.
The Wide-field X-ray Monitor (WXM) is one of the scientific
instruments carried on the High Energy Transient Explorer 2 (HETE-2)
satellite launched in October 2000. The WXM consists of three elements: (1) four identical Xe-filled one-dimensional position-sensitive proportional counters, two in the spacecraft X-direction and two in the Y-direction, (2) two sets of one-dimensional coded apertures orthogonally mounted above the counters in the X and Y-direction, and (3) the main electronics that processes analog signals from the counters. The WXM counters are sensitive to X-rays between 2 keV and 25 keV within a field-of-view of about 1.5 sr with a total detector area of about 350 cm<sup>2</sup>. The combination of the apertures and the counters provides GRB locations with accuracy ~10 arcmin. The counters and electronics are developed and fabricated by RIKEN, and the apertures and on-board software are designed and provided by Los Alamos National Laboratory. The WXM plays a major roll in the GRB localization and its spectroscopy in the energy range between 2 keV and 25 keV. During the first year of observations, a number of steady X-ray sources as well as high-energy transients were detected with the WXM. Observing Crab nebula and Sco X-1, we have calibrated the detector alignment between the WXM and the optical camera system with 2 arcmin accuracy. As of 29 July 2002, nineteen GRBs have been localized with the WXM in the 18 months of stable operations. Twelve of them were reported to the GCN within a delay of 10 hours, and 4 optical transients were identified by ground based telescopes. The energy response of the detectors has also been calibrated using the Crab spectrum. We report the in-orbit performance of the WXM instrument during the first 18 months.
We are developing Monitor of All Sky X-ray Image (MAXI) which will be mounted on the Japanese Experiment Module of the International Space Station. MAXI is an all-sky X-ray monitor which scans the sky in every 90 minutes. The sensitivity will be as high as 7 mCrab (5 (sigma) level) in one scan and 1 mCrab in one-week accumulation. The GSC (Gas Slit Camera) instrument consists of twelve one-dimensional position sensitive proportional counters using the Xe++CO<SUB>2</SUB> gas and the carbon fiber anodes of 10micrometers diameter. The window size is 272 x 190 mm. The position is obtained by the charge division method. It is used to identify the source in the long rectangular field-of-view (1.5 x 80 degrees). Three cameras will be set to cover the 1.5 x 160 degrees arc. The position resolution is essentially important, which becomes better in the higher gas gain. We have tested gas mixtures of Xe+CO<SUB>2</SUB>with CO<SUB>2</SUB> equals 0.2\%, 0.5\%, 1\%, 3%. The CO<SUB>2</SUB> equals 0.5\% showed the most uniform gas gain, but has a little after pulses. We chose the Xe (99%) + CO<SUB>2</SUB> (1%) combination for the flight counters. It can achieve the uniform gas gain in the cell and negligible after-pulse in high operating voltage. The engineering model of the counter (EM1) was build. We have tested the position resolution and the energy resolution across the counter. The position resolution and the energy resolution depend on the X-ray energy. On the basis of these results, together with the collimator response, we performed a realistic simulation.
The position dependency of gas amplification in the proportional counter (PC) is investigated. We have been developing one-dimensional position sensitive PCs for MAXI/GSC and HETE/WXM and found that anomalous gas amplification occurs in a high bias voltage, even while the PC is still operated in the proportional region. This effect depends on the position where the X-ray is absorbed. Therefore it appears as a hard tail, a soft tail, or a broad peak in the traditional PC, depending on the shape of the gain curve across the cell. It degrades the apparent energy resolution. Especially, a position sensitive proportional counter (PSPC) is operated with rather high bias voltage to give higher positional resolution. We encounter the difficulty to achieve good position and energy resolutions at the same time. In this work, we have examined the anomalous gas amplification for various gas mixtures of Xe + CO<SUB>2</SUB>, Ar + CO<SUB>2</SUB> and Ar + CH<SUB>4</SUB>, for gas gain up to approximately 20000, and for energies from 6 to 17 keV to understand the phenomena.
Monitor of the All-sky X-ray Image (MAXI) is the first payload for the Japanese Experiment Module (JEM) on the International Space Station (ISS). It is designed for monitoring all-sky in the X-ray band. Its angular resolution and scanning period are about 1 arc-degree and 100 minutes, respectively. MAXI employs two types of X-ray camera. One is Gas Slit Camera (GSC), the detectors of which are one dimensional position sensitive proportional counters. Another is Solid-state Slit Camera (SSC). We mainly report on SSC. We employ a pair of SSCs, each of which consists of 16 CCD chips. Each CCD chips has 1024 X 1024 pixels, and the pixel size is 24 X 24 micrometer. The CCDs are to be operated at -60 degrees Celsius using Peltier coolers. Optical light is blocked by aluminum coat on the CCDs instead of fragile aluminized film. SSC achieves an energy resolution of 152 eV in FWHM at 5.9 keV. The energy range is 0.5 - 10 keV.
Monitor of All-sky X-ray Image (MAXI) is the first astrophysical payload which will be mounted on the Japanese Experiment Module Exposed Facility of International Space Station in 2004. It is designed for monitoring all-sky in the x-ray band by scanning with slat collimators and slit apertures. Its angular resolution and scanning period are approximately 1 arc degree and 90 minutes, respectively. MAXI employs two types of X-ray camera. One is Gas slit Camera (GSC), the detectors of which are 1D position sensitive proportional counters. Its position resolution is approximately 1.0 mm along carbon anode wires. GSC covers the 2.0 - 30 keV energy band. We have found an interesting feature in the energy response: monochromatic X-rays are detected with a peculiar hard tail in the spectra. The physical mechanism causing the hard tail is still unclear. The other camera is Solid-state Slit Camera (SSC). We employ a pair of SSCs, each of which consists of sixteen CCD chips. Each CCD has 1024 X 1024 pixels, and each pixel is 24 X 24 micrometers. The CCDs are to be operated at -60 degree using Peltier coolers. SSC covers an energy range of 0.5 - 10.0 keV. The test counters and test chips are evaluated in NASDA, Riken, and Osaka-University. The continuous Ethernet down link will enable us to alert the astronomers in all over the world to the appearance of X-ray transients, novae, bursts, flares etc. In this paper we will report on the current status of the MAXI mission.
The Wide-field X-ray Monitor is one of the scientific instruments carried on the High Energy Transient Explorer 2 (HETE-2) satellite planned to be launched in May, 2000 (on the present schedule in February, 2000). HETE-2 is an international mission of a small satellite dedicated to provide broad band observations and accurate localizations of gamma-ray bursts (GRBs). The first HETE satellite was lost due to a Pegasus XL rocket mishap on November 4, 1996. The HETE-2 has been developed on basically the same concept except that the UV cameras were replaced with the Soft X-ray Camera. A unique feature of this mission is its capability of determination and transmission of GRB coordinates in near real time through a network of primary and secondary ground stations.
The hard x-ray detector (HXD) is one of the three experiments of the Astro-E mission, the fifth Japanese X-ray Satellite devoted to studies of high energy phenomena in the universe in the x-ray to soft gamma-ray region. Prepared for launch at the beginning of 200 via the newly developed M-V launch vehicle of the Institute of Space and Astronomical Science, the Astro-E is to be thrown in to a near-circular orbit of 550 km altitude, with an inclination of 31 degrees. The flight model has been finished assembled this year, and we carried out various tests to verify the performance. We acquired the background spectrum at sea level, and confirmed that our system is operating effectively in reducing the background level. The HXD will observe photons in the energy range of 10-600 keV, and the calculations based on the preflight calibration suggest that the HXD will have the highest sensitivity ever achieved in this energy range. We also verified that our electronic system will maintain its performance against charged particle events expected in orbit.
Monitor of All-Sky X-ray Image (MAXI) is the first astrophysical payload for the Japanese Experiment Module (JEM) on the International Space Station. It is designed for monitoring all sky in the x-ray band. Two kinds of x-ray detectors, the gas slit camera and the solid-state slit camera, are employed. The former is the gas proportional counter with 1D position sensitivity and the latter is the x-ray CCD. We have designed and constructed the engineering models of both detectors. We have also developed an x-ray irradiation facility in the Tsukuba Space Center of National Space Development Agency of Japan. We report the status of the mission and introduce the x-ray irradiation facility.
The Hard x-ray Detector (HXD) is one of three instruments on the fifth Japanese x-ray astronomy satellite, Astro-E, scheduled for launch in 2000. The sensitivity of the Astro-E HXD will be higher by more than one order of magnitude than that of nay previous instrument between 10 keV and several 100 keV. The electronic system is designed to handle many independent data channels from the HXD within the limitation of size and power consumption required in Astro-E. In this paper, we will present the design and the preliminary performance of the processing electronic system.
NASDA (National Space Development Agency of Japan) has selected MAXI as an early payload of the JEM (Japanese experiment module) Exposed Facility (EF) on the space station. MAXI is designed for all sky x-ray monitoring, and is the first astrophysical payload of four sets of equipment selected for JEM. MAXI will monitor the activities of about 1000 - 2000 x-ray sources. In the present design, MAXI is a slit scanning camera system which consists of two kinds of x-ray detectors; one with one-dimensional position sensitive proportional counters and the other with an x-ray CCD array employed for one-dimensional imaging. MAXI will be able to detect one milli-Crab x-ray sources in a few-day observations. The whole sky will be covered completely in every orbit of the space station. MAXI will be capable of monitoring variability of galactic and extragalactic sources on timescales of days with a sensitivity improvement of a factor of 5 or more over previous missions. NASDA and RIKEN have jointly begun the design and construction of MAXI. The payload will be ready for launch in 2003. In this paper we present the scientific objectives of MAXI, a basic design and some simulation results, after introducing the present status of JEM.
The wide-field x-ray monitor (WXM) is one of the three scientific instruents onboard high energy transient experiment (HETE) satellite, which was launched in 1996. The primary objective of HETE is to carry out the first multi- wavelength study of gamma-ray bursts with UV, x-ray, and gamma-ray instruments mounted on a single, compact spacecraft. WXM has been designed to undertake comprehensive x-ray spectra observations and quickly determine small error boxes of GRB locations within a large field of view of about 1.5 steradian. It is based on the principle of coded aperture imaging. It has four identical one-dimensional position sensitive proportional counters (PSPCs), one pair in each of two orthogonal directions. Each PSPC is filled with 1.4 atm Xe (97%) and CO2 (3%), equipped with three resistive carbon anodes of 10 micrometer diameter, and sensitive to x-rays between 2 and 25 keV. It provides position resolution of about 1.0 mm (FWHM), and energy resolution of about 17% (FWHM) at 8 keV.
We propose MAXI (monitor of all-sky x-ray image), an x-ray all sky monitor on the exposed facility (EF) of the Japanese Experiment Module (JEM) on the International Space Station. The construction of the EF of JEM is scheduled in 2001. In the present design, MAXI consists of two slit scanning camera systems: one with one-dimensional position sensitive proportional counters, and the other with an x-ray CCD array employed for one-dimensional imaging with fast readout. We plan to monitor broad categories of x-ray sources, both galactic and extragalactic. In particular, we attempt to monitor dim sources (approximately several mCrab flux) on timescales of days to months.
Astro-E is the x-ray satellite to be launched in the year 2000 by Inst. of Space & Astronautical Science. This report deals with the design and expected performance of the hard x-ray detector (HXD), one of the 3 experiments aboard Astro- E. The HXD is a combination of GSO/BGO well-type phoswich counters and silicon PIN diodes: the two combined will cover a wide energy band of 10 - 700 keV. The detector is characterized by its low background of approximately 10<SUP>-5</SUP>/s/cm<SUP>2</SUP>/keV and its sensitivity higher than any past missions between a few 10 keV and several 100 keV. Combined with the other 2 experiments, a micro-calorimeter array (XRS) and 4 CCD arrays (XIS), both with x-ray mirrors, the mission will cover the soft and hard x-ray range at a highest sensitivity.
The ASTRO-E satellite is scheduled for launch in 2000 by the Institute of Space and Astronautical Science (ISAS). In this paper the design and performance of the hard x ray detector (HXD) developed for ASTRO-E are described. The HXD is a combination of YAP/BGO phoswich scintillators and silicon PIN diodes covering a wide energy band of 10 - 700 keV. The detector background is reduced down to several times 10<SUP>-6</SUP>c/s/cm<SUP>2</SUP>/keV, and the sensitivity of the HXD is more than one order of magnitude higher than any other past missions in the range of a few 10 keV to several 100 keV. Thus ASTRO-E HXD is expected to achieve an extreme high performance for detecting cosmic hard x rays and low-energy gamma rays. Astrophysics to be explored with the HXT are expected to be extremely widespread and rich.
The X-ray detection system used to calibrate the Advanced X-ray Astrophysics Facility (AXAF) mirrors will include gas flow and sealed proportional counters. To meet the ultimate 1 percent goal of the calibration project, the transmission and uniformity of the windows must be well known for the soft X-ray wavelengths involved. Various window materials for use with proportional counters are examined for transmission at X-ray wavelengths in the range of 0.1 to 5.9 keV. These include the usual window materials (polypropylene and beryllium), as well as materials only recently employed for detector applications (polyimide and diamond). The transmission uniformity of beryllium at 1.49 keV is examined with a microchannel plate detector, producing a 'shadowgraph' of the window material illuminated with soft X-rays. This technique allows us to investigate nonuniformities on a spatial scale of about .2 mm.