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 proposed by the X-ray group of the Institute of Physical and Chemical Research, RIKEN, in 1996 to the National Space Development Agency of Japan, NASDA (now part of JAXA), and approved in 1997.

The main objectives of MAXI are early detection of X-ray transient events, and monitoring the intensity fluctuation of known X-ray sources over long periods by scanning the all sky in soft and hard X-ray.
To achive these goals, MAXI comprises of :

  • two semi-circular arc-shaped X-ray slit cameras with wide FOVs. In the 92 minutes it takes the ISS to orbit the earch, MAXI gets a 360 deg image of the entire sky.
  • two kinds of X-ray detectors, collecting events from the slit cameras: a gas proportional counters, the Gas Slit Camera (GSC; 2-30 keV), and a X-ray CCD, Solid-state Slit Camera (SSC; 0.5-12 keV).
The Kibo Exposed Facility and MAXI were launched by the space shuttle STS-127 Endeavour on July 15 2009 and delivered to the ISS. MAXI started observations in August 2009 with an orginal two years operation subsequently extended. Currently JAXA have approved operation till March 2021.

The data processing and operations are conducted jointly by JAXA, RIKEN, Osaka University, Tokyo Institute of Technology, Aoyama Gakuin University, Nihon University, Kyoto University, Miyazaki University and Chuo University. The MAXI archive is hosted at the DARTS/ISAS and a copy is also present at the HEASARC.

Latest News

19 Dec 2022

MAXI data version 2.7 is now available All MAXI data have been reprocessed and now online at DARTS and HEASARC . The reprocessing includes standardization of the FITS headers, changes in the content for some of the files and a consist handling of data gaps.

13 Apr 2021

MAXI 7 Year GSC Source Catalog The MAXI GSC 7 Year High and Low Galactic Latitude Source Catalog (3MAXI) is now available. The catalog lists both high and low galactic latitude X-ray sources detected by the MAXI Gas Slit Camera (GSC) in its first 7 years of operations.

20 Aug 2020

MAXI SSC All-Sky Images The MAXI SSC All-Sky two year maps (17-Aug-2009–27-Aug-2011) are now available at the HEASARC. The README file contains details of the spectral range and other useful details about the maps.

25 Sep 2019

The MAXI CALDB has been updated for the GSC and SSC instruments.

25 Oct 2018

MAXI archive opens at HEASARC
The MAXI archive has been hosted at the DARTS/ISAS and a copy is now also available from the HEASARC. The two archives are syncronized weekly. The archive is populated with the outputs of the data processing that occurs in Japan. Together with the archive opening, the MAXI software package has been released with HEASoft 6.25 and the calibration data are now also available within CALDB

23 Oct 2018

First release of the MAXI software package within HEAsoft 6.25 . The MAXI software package includes routine to allow the analysis of the data in the MAXI archive.