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: email@example.com
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
in one day
102 X-ray nova ! sensitivity
Detection in one day
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
Galactic coordinates “movies” of the X-ray sky. Slit camera and Field of view
International Japanese Experiment
Space Station (ISS) Module (JEM)
collimator Forward view
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
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.
Alert and data publication
Proportional counter collimator
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
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)
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
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
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
Alert delay is less than 30 s after the MAXI scan.
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
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
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.