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					                                                                                                             Monitor of All-sky X-ray Image
                                                                                                    MAXI mission on ISS
                                                                    Tatehiro Mihara, Mitsuhiro Kohama, Motoki Nakajima (RIKEN),
                                                                    Masaru Matsuoka, Shiro Ueno, Hiroshi Tomida, Naoki Isobe, Haruyoshi Katayama, Mikio Morii (JAXA),
                                                                    Hiroshi Tsunemi, Emi Miyata (Osaka U),    Nobuyuki Kawai, Jun Kataoka (Tokyo Tech U),
                                                                    Atsumasa Yoshida, Kazutaka Yamaoka (Aoyama U), Hitoshi Negoro (Nihon U)

                                                              MAXI website: http://www-maxi.tksc.jaxa.jp/                                                                          E-mail: mihara@crab.riken.jp
      Abstract
 The Monitor of All-sky X-ray Image (MAXI) is a highly sensitive all-sky monitor which will be attached to the Japanese Experiment Module of the
International Space Station in 2008. MAXI utilizes scanning X-ray slit-cameras which consist of two kinds of instruments. The Gas Slit Camera
(GSC) is the proportional counter with Xe and is sensitive to 2 - 30 keV. The Solid-state Slit Camera (SSC) is the CCD sensitive to 0.5 - 10 keV.
The slit cameras have long field of views, and scan almost the whole sky in one orbit of ISS. As an X-ray all-sky monitor, MAXI will have an
unprecedented sensitivity of 7 mCrab in one orbit scan, and 1 mCrab in one week. MAXI can monitor extragalactic objects as well as the galactic
objects. MAXI will make a dynamic catalog of more than 1000 X-ray sources in time scales from hours to years. The alert of bursts and novae
will be promptly informed to the world through the internet. The flight detectors were already built, and the assembling and calibration of the
detectors and collimators are in progress.
                                                                                                                                            Observational Targets                                     Long-term High-sensitivity X-ray monitoring
                                                                                                                                                                                                                                             105
                                                                                                                                                                                                                                                                                   Spectrum
                                                                                                                                                                                                                                                                                   in one day
                                                                                                                                                                                                                                             104
                                                                                                                Intensity [mCrab]




                                                                                                                                                                                                                         Intensity [mCrab]
                                                                                                                                                                                               Current
                                                                                                                                                                                               sensitivity                                   103

                                                                                                                                                                                                                                                                                                                           Current
                                                                                                                                                                                                                                             102                X-ray nova !                                               sensitivity
                                                                                                                                                                                                                                                                                                  1orbit
                                                                                                                                                                                                                                             101
                                                                                                                                                                                                                                                      Detection in one day
                                                                                                                                                                                                                                                                                                  1week
                                                                                                                                                                                           MAXI                                               1                                                                    MAXI
                                                                 Simulated MAXI observation.
                                                                                                                                                                                                                                                     0                    100                    200               sensitivity
                                                                 X-ray sources are picked up                                                                                               sensitivity
                                                                 from this MAXI map and light                                                           Distance [light-yr]                                                                                      Time [ days ]             (Tanaka et al.)
                                                                 curves for all the sources are                                         Previous ASMs targeted bright galactic objects.                       MAXI can discover a distant X-ray nova and trace its light
                                                                 obtained. MAXI monitors flux                                           MAXI can observe beyond our galaxy.                                  curve, which cannot be observed with previous ASMs.
                                                                 changes of more than 1000
                                                                 X-ray sources in time
                                                                                                                                                                                                             Much more bursts will be detected. A bright nova will be
                                                                                                                                                                                                             monitored from the rising phase to the decaying end.
                                                                 scales from 96 minutes to
                                                                 years. MAXI takes
                                                                                                                                                MAXI instruments
                                         Galactic coordinates    “movies” of the X-ray sky.                                                                                                                                                  Slit camera and Field of view
                    International                           Japanese Experiment
                 Space Station (ISS)                           Module (JEM)
                                                             Pressurized
                                                                                                                                                                                                                                                                                                          Zenithal view
                                                                                         Robot arm
                                                             Module                                                                                                                                                                                      slit
          forward

                                                                                                                                                                                                   collimator                                                      Forward view
                                   Japanese
                                  Experiment
                                    Module
                                                                              Exposed facility
                                                                                                                                                   Solid-state Slit
                                                                                                                       Gas Slit Camera (GSC)       Camera (SSC)
        altitude: 330 ~ 480 km                               MAXI                                                                                                                                                           One-dim. detector
        inclination: 51.6 deg.                                                                                            Weight 500 kg, Size 1.8 ×1.2×0.8m                                           X-ray from the sources goes through the slit and is
        orbital period: 96 minutes
                                                                                                                                                                                                     detected by the one-dimensional detector. The X-ray
                   Solid-state Slit Camera (SSC)                                                                                                  Gas Slit Camera (GSC)                              position in the detector corresponds to the location of the
                                                                                            ΔE=145eV
                                                                                                                                                                                   48cm
                                                                                                                                                                                                     source in the F.O.V. The collimator defines the long F.O.V.
            20cm                                                                                                                                                                                     Thus the source position (α,δ) is obtained. MAXI has two
                                                                                                                                                                                                     kinds of slit cameras: GSC and SSC. Six GSC and two
                                                                                                                                                                                                     SSC can cover two F.O.V.s: forward and zenithal. The
                                                                                                                                                                                                     F.O.V.s scan almost the whole sky with 96 minutes
                                                                                                                                                                                                     rotation of ISS.
                                                                                                                                                 36cm
                                                                                                                                                                                                                                             Alert and data publication
                                                                                                                                            Proportional counter              collimator
                                                                                                                                                                                                                                                                                                   MAXI operation
                                                                                                                                                                                                                                                     Low-rate data 1553B
                SSC camera and CCD                              Spectra obtained with SSC                                            GSC utilizes gas proportional counters sensitive to 2 - 30
                                                                                                                                    keV. The one-dimensional X-ray position is given by the                                                                                                                 Database
 SSC utilizes X-ray CCDs sensitive to 0.5 - 10 keV. One stage                                                                                                                                                                                        Mid-rate data Ethernet
                                                                                                                                    charge division method of the carbon fiber anodes with                                                                      Alert
Peltier cooler is attached under each chip. Pixel size is 24×
                                                                                                                                    10μm diameter. The 12 counters makes very large 5000
24μm, and pixel number is 1024×1024. The 16 CCD × 2                                                                                                                                                                                                               request
                                                                                                                                    cm2 area. Metorex (Oxford) manufactures large-area                                                                                                                             Data-
cameras makes 200 cm2. Hamamatsu CCD has a deep                                                                                                                                                                                                                    data
                                                                                                                                                                                                                                                                                                                   base
                                                                                                                                    sealed Xe counters with space quality.                                                                   observers
depletion layer and a good energy resolution.
                                                                                                                                                                                                          Real time contact will be established in 12~17 hours
                                  MAXI data sheets                                                                                             MAXI status and schedule                                  per day. The data is automatically processed in JAXA
        Covering fraction         160 deg (long) ×1.5 deg (FWHM) × 2 .FO.V.
        of the sky                F.O.V. 2 %                                                                           • 2004.3. Critical Design Review (CDR) was passed. The                            Tsukuba space center. When a burst or a nova is
                                  Scans 90~98% with 96 minutes rotation of ISS.
                                                                                                                       fabrication of flight counters and parts and their calibration                    detected, an alert is issued within 30 s to observers in all
        Position resolution       Point spread function: 1.5 deg (FWHM)
GSC




                                  Localization accuracy: 6 arcminutes.                                                 have started.                                                                     over the world. The MAXI data goes public within 1 day.
        Energy band, resolution   2~30 keV, 18%@5.9 keV.                                                               • 2006.4. The first assembly of the whole payload.
        Timing accuracy           120μsec to GPS time.
        Detection limit (5σ)      7 mCrab (1orbit), 1 mCrab (1week).
                                                                                                                       • 2008 Launch by H-IIA rocket.                                                                                                                           now
                                                                                                                                                                                                                         2000                 2001    2002       2003   2004     2005     2006    2007      2008     2009     2010   2011
        Covering fraction         90 deg (long) ×1.5 deg (FWHM) × 2 .FO.V.
        of the sky                F.O.V. 1.3 %                                                                         ○GSC                                                                                                Basic design                    Detailed design      Fabrication and assembly                   MAXI operation
                                  Scans 70% with 96 minutes rotation of ISS.                                            • Counters: 15 counters were already made out of 12
                                                                                                                                                                                                         MAXI schedule
SSC




        Position resolution       Point spread function: 1.5 deg (FWHM)                                                 flight and 4 spare counters. The calibration of five of them
                                  Localization accuracy: 6 arcminutes.
        Energy band, resolution   0.5~10keV, < 150 eV@5.9 keV.
                                                                                                                        were finished.                                                                                                               PDR                  CDR           1st assembly         H-IIA / HTV launch

        Timing resolution         3~16sec depending on the readout mode of CCDs.                                        • Collimators: Test of EM model was finished. PFM is in                                                                                   GSC fabri. & calibration
                                                                                                                                                                                                                                                                                                       Payload test
        Detection limit (5σ)      20 mCrab (1orbit), 2 mCrab (1week)                                                    fabrication.                                                                                                                              SSC fabri. & calibration
        Real time data            Real time contact will be in more than 50% of the observation time.                                                                                                                                                                                            software
                                                                                                                       ○SSC
Alert




                                  Alert delay is less than 30 s after the MAXI scan.
                                                                                                                                                                                                                                                         RXTE                                                                 Lobster-ISS
        Stored data               Off-contact data are stored in the data recorder and are down-linked in the
                                  next contact.                                                                         • Cameras: Test of EM camera was finished. PFM                                                                                     Chandra
                                                                                                                                                                                                         Missions




                                                                                                                                                                                                                                                          XMM-Newton
                                  Alert delay is 20 minutes ~3 hours.                                                   camera is being designed and manufactured. Temperature                                                                                                   INTEGRAL
        Alert                     Bursts and novae are alerted to the users through the internet.
                                                                                                                        control is being improved.                                                                                                                                                     Swift
User




        Data                      Images, spectra, and light curves of any X-ray sources and sky-areas can                                                                                                                                                                                             ASTRO-E2
                                  be obtained through web browsers in the internet.                                     • CCD chips: Fabrication and screening were finished. 48                                                                                                                                       GLAST

                                                                                                                        flight chips are ready.

				
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posted:5/21/2013
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