Monitor of All-sky X-ray Image (MAXI) - 04.09.15

Overview | Description | Applications | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
The Monitor of All-sky X-ray Image (MAXI) investigation is designed to continuously monitor, through a systematic survey, X-ray sources and variabilities as the International Space Station (ISS) orbits Earth. Located at Equipment Exchange Unit (EER) site 1 on the Japanese Experiment Module - Exposed Facility (JEF), MAXI is comprised of a couple highly sensitive X-ray detectors, the Gas Slit Camera (GSC) and the Solid-state Slit Camera (SSC). Besides the goal of performing a complete sky survey, this research helps to address fundamental astrophysics questions and allows researchers to better understand the current state and evolution of our Universe.
Science Results for Everyone
Better than Superman? An X-ray monitor on the space station examined the entire sky for galactic transient phenomena and discovered new black hole candidates; reported more than 20 binary X-ray pulsar outbursts; detected X-ray flares from 12 stars in its first two years, providing a unified picture for star flaring; and observed for the first time the instant that a massive black hole swallowed a star. The investigation released a catalog for high Galactic-latitude sky sources and revealed the existence of a hypernova remnant estimated to be 3 million years old, believed to be the first in our galaxy.

The following content was provided by Masaru Matsuoka, Ph.D., and is maintained in a database by the ISS Program Science Office.
Information provided courtesy of the Japan Aerospace and Exploration Agency (JAXA).
Experiment Details


Principal Investigator(s)

  • Masaru Matsuoka, Ph.D., Institute of Physical and Chemical Research, Saitama, Japan

  • Co-Investigator(s)/Collaborator(s)
  • Atsumasa Yoshida, Ph.D., Aoyama Gakuin University, Kanagawa, Japan
  • Masashi Kimura, Osaka University, Osaka, Japan
  • Maki Ishikawa, SOKENDAI, Japan
  • Yujin E. Nakagawa, Institute of Physical and Chemical Research, Saitama, Japan
  • Ken Ebisawa, Japan Aerospace Exploration Agency, Kanagawa, Japan
  • Mutsumi Sugisaki, Institute of Physical and Chemical Research, Japan
  • Motoko Serino, Institute of Physical and Chemical Research, Saitama, Japan
  • Mikio Morii, Tokyo Institute of Technology, Tokyo, Japan
  • Doyuki Yamamoto, Institute of Physical and Chemical Research, Japan
  • Jyuri Sugimoto, Institute of Physical and Chemical Research, Japan
  • Toshihiro Takagi, Institute of Physical and Chemical Research, Japan
  • Hiroshi Tsunemi, Ph.D., Osaka University, Osaka, Japan
  • Eibun Yoshikawa, Institute of Physical and Chemical Research, Japan
  • Takuya Onodera, Nihon University, Japan
  • Shogun Sasaki, Osaka University, Japan
  • Hirotaka Uchida, Osaka University, Japan
  • Kosuke Fukushima, Nihon University, Japan
  • Ryuichi Usui, Tokyo Institute of Technology, Tokyo, Japan
  • Kazuhito Ishikawa, Tokyo Institute of Technology, Japan
  • Kenshun Yoshii, Tokyo Institute of Technology, Japan
  • Yutaro Tachibana, Tokyo Institute of Technology, Japan
  • Kazuhiko Suzuki, Nihon University, Japan
  • Nobuyuki Kawai, Ph.D., Tokyo Institute of Technology and Institute of Physical and Chemical Research, Tokyo, Japan
  • Motoki Nakajima, Nihon University, Chiba, Japan
  • Megumi Shidatsu, Kyoto University, Kyoto, Japan
  • Taiki Kawamuro, Kyoto University, Japan
  • Takaiku Hori, Kyoto University, Japan
  • Takanori Sakamoto, Aoyama Gakuin University, Japan
  • Yuki Nakano, Aoyama Gakuin University, Japan
  • Yuta Kawakubo, Aoyama Gakuin University, Japan
  • Hikaru Otsuki, Aoyama Gakuin University, Japan
  • Makoto Yamauchi, University of Miyazaki, Miyazaki, Japan
  • Yuji Ogawa, Miyazaki University, Japan
  • Shiro Ueno, JAXA, Japan
  • Hisamiki Yamada, Miyazaki University, Japan
  • Koshiro Yoshidome, Miyazaki University, Japan
  • Yoshitaka Moroka, Miyazaki University, Japan
  • Yoko Tsuboi, Chuo University, Tokyo, Japan
  • Masaya Higa, Chuo University, Japan
  • Atsushi Kawagoe, Chuo University, Japan
  • Kazuki Yamaoka, Nagoya University, Japan
  • Tatehiro Mihara, Institute of Physical and Chemical Research, Saitama, Japan
  • Hitoshi Negoro, Ph.D, Nihon University, Tokyo, Japan
  • Yoshihiro Ueda, Ph.D., Kyoto University, Kyota, Japan
  • Hiroshi Tomida, Japan Aerospace Exploration Agency, Tsukuba, Japan
  • Satoshi Nakahira, Aoyama Gakuin University, Kanagawa, Japan

  • Developer(s)
    Japan Aerospace Exploration Agency (JAXA), Tsukuba, Japan

    Sponsoring Space Agency
    Japan Aerospace Exploration Agency (JAXA)

    Sponsoring Organization
    Information Pending

    Research Benefits
    Information Pending

    ISS Expedition Duration
    March 2009 - Ongoing

    Expeditions Assigned

    Previous ISS Missions

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    Experiment Description

    Research Overview

    • The long-term time variability and random transient events are difficult to study with pointing telescopes, and require dedicated all sky mission. To research exotic phenomena systematically, the latest X-ray astronomical catalog is needed.
    • MAXI continues to detect X-ray transient phenomena and rapidly inform the world of its position and brightness. The observation results about 1000 X-ray sources are provided in every day. MAXI also provides the latest X-ray catalog.
    • MAXI will transmit an alert through the Internet when it detects any significant transient event, Other observatories or satellites can turn their telescopes toward the source to make follow-up observations.

    Monitor of All-sky X-ray Image (MAXI) is an X-ray all-sky monitor, to scan almost the entire sky once every 96 minutes for a mission life of more than two years. MAXI on ISS has been observing the X-ray sky from Aug 2009. The detection sensitivity will be about 20 mCrab(5 sigma level) for one-orbit MAXI operation, 2–3 mCrab for one day, and 1 mCrab for one week, reaching a source confusion limit of 0.2 mCrab in one-year observation. The systematic survey of the X-ray variabilities to study the nature of active celestial objects is an important objective of MAXI. So far, MAXI has detected many X-ray transient phenomena and rapidly informed the world of its sky positions and X-ray brightness. In principle. The astronomical data obtained with MAXI is now available at the MAXI web site.

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    Space Applications
    Many X-ray sources are transients that escape detection because most telescopes have narrow fields of view. MAXI’s wide view and rapid notifications, up to 1,000 a day, help alert other observatories so they can capture data about these sources in a  broad range of spectra.


    Earth Applications
    Astronomical data from MAXI, and from facilities alerted by MAXI, help scientists in studying the origins of matter and energy in the universe.

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    Operational Requirements
    Since the continuous monitoring of the X-ray sky is important, MAXI is conducting the observation in 24x7. Continuous power and thermal control is required. To catch the transient phenomenon quickly, real time data transfer important. It is also important to minimize the data loss in order to make a complete sky survey.

    Operational Protocols
    The X-ray camera of MAXI must stop the observation during the sun is in the field of view or ISS is in the dense cosmic-particle regions (e.g. South Atlantic anomaly). It is necessary to properly control the X-ray cameras. It is important to predict the attitude and position of ISS precisely. The data broadcasted on ISS is also utilized for the camera control.

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    Results/More Information

    Information Pending

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    Results Publications

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    Ground Based Results Publications

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    ISS Patents

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    Related Publications

      Katayama H, Tomida H, Matsuoka M, Tsunemi H, Miyata E, Kamiyama D, Nemes N.  Development of the x-ray CCD cameras for the MAXI mission. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 2005; a541: 350-356. DOI: 10.1016/j.nima.2005.01.075.

      Sugizaki M, Mihara T, Serino M, Yamamoto T, Matsuoka M, Kohama M, Tomida H, Ueno S, Kawai N, Morii M, Sugimori K, Nakahira S, Yamaoka K, Yoshida A, Nakajima M, Negoro H, Eguchi S, Isobe N, Ueda Y, Tsunemi H.  In-orbit performance of MAXI Gas Slit Camera (GSC) on ISS. Publications of the Astronomical Society of Japan. 2011 November 25; 63(sp3): s635-s644. DOI: 10.1093/pasj/63.sp3.S635.

      Ueno S, Tomida H, Isobe N, Katayama H, Kawasaki K, Yokota T, Kuramata N, Matsuoka M, Mihara T, Sakurai I, Nakajima M, Kohama M, Tsunemi H, Miyata E, Kawai N, Kataoka J, Serino Y, Yamamoto Y, Yoshida A, Negoro H.  Development status and performance estimation of MAXI. UV and Gamma-Ray Space Telescope Systems; 2004 October 11 197-208.

      Mihara T, Kawai N, Yoshida A, Sakurai I, Kamae T, Matsuoka M, Shirasaki Y, Sugizaki M, Yuan W, Tanaka I.  Performance of the GSC engineering-counter for MAXI/ISS. X-Ray and Gamma-Ray Instrumentation for Astronomy XII; 2002 January 31 173-186.

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    Related Websites
    The MAXI Experiment
    The information on this web page was duplicated from information provided by JAXA. Please visit the Japan Aerospace Exploration Agency's Kibo Experiments to learn more about this payload and others.
    MAXI (Japanese)

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    image Pictured above is the Monitor of All-sky X-ray Image (MAXI) that is mounted externally on the Japanese Experiment Module (JEM) onboard the ISS. (Image provided by JAXA.)
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    image The "First Light" all-sky X-ray image obtained with the Gas Slit Camera (GSC) of MAXI over one ISS orbit. Image courtesy of Japan Aerospace Exploration Agency (JAXA).
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    image NASA Image: S127E009561 - View of MAXI attached to the Japanese Experiment Module - Exposed Facility (JEF). Photo was taken during STS-127 / Expedition 20 Joint Operations.
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    image On March 28, 2011, NASA's Swift detected intense X-ray flares thought to be caused by a black hole devouring a star. In one model, illustrated here, a sun-like star on an eccentric orbit plunges too close to its galaxy's central black hole. About half of the star's mass feeds an accretion disk around the black hole, which in turn powers a particle jet that beams radiation toward Earth.
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