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Monitor of All-Sky X-ray Image (MAXI)

MAXI in the clean room with all final covers installed

The Monitor of All-sky X-ray Image (MAXI) is the first experiment to be installed on the Japanese Experiment Module Exposed Facility (JEM-EF or Kibo-EF) on the International Space Station (ISS), and the first high energy astrophysical experiment placed on the space station. MAXI was launched with the Kibo Exposed Facility on the space shuttle Endeavour (STS-127) on July 15, 2009 and delivered to the ISS. MAXI started observations in August 2009 and was originally intended for a two year operations period, but has been extended several times to remain operational to the current time.

Mission Characteristics

Lifetime
August 2009– present
Special Features
  • All sky survey over each ISS orbit
  • Rapid detection of transients and variable sources

Payload

Gas Slit Cameras (GSC)

Energy Range
2–30 keV
Field of View
160° × 1.5°
Angular Resolution
1.5° (FWHM PSF)
<6′ position determination
Sensitivity
10 mCrab (1 orbit); 1 mCrab (1 week) (5 σ)
Energy Resolution
18% at 5.9 keV
Time Resolution
120 µs
12 xenon-filled proportional gas counters with slit collimators give the GSC a 1.5° x 160° wide field of view in each of the horizontal and zenithal directions. Sees 2% of all-sky at an instant, 90–98% of the sky every orbit (roughly 96 minutes)

Solid-state Slit Cameras (SSC)

Energy Range
0.5–10 keV
Field of View
90° × 1.5 °
Angular Resolution
1.5° (FWHM PSF); <6′ position determination
Sensitivity
20 mCrab (1 orbit), 2 mCrab (1 week) (5 σ)
Energy Resolution
<150 eV at 5.9 keV
Time Resolution
3–16 s (depending on readout method)
One dimensional position sensitive X-ray detector (CCDs). The collimating slit aperture providing a narrow field of view (1.5° by 90°) in the horizontal (ISS forward motion) and vertical (zenithal) directions. Sees 1.5% of the entire scan at an instant, and scans 70% of all-sky every orbit (96 minutes).

Science Highlights

  • Monitoring of a variety of variable and transient X-ray sources
  • Rapid locating of burst events such as novae, supernovae, and gamma-ray bursts found initially by other observatories, refining their sky locations more precisely.
  • Discovery of numerous X-ray transient sources including black hole candidates and new soft gamma-ray burst sources.
  • Transient event alerts: alerts to other observatories are distributed within 30 s of detection.

Archive

The HEASARC hosts event data, and calibration files for MAXI.

MAXI at RIKEN MAXI at DARTS MAXI at HEASARC MAXI bibliography

All Missions Time Ordered List Energy Ordered List