MAXI Archive: Getting started


The MAXI science data are organized by sequence, where a sequence corresponds to an observation of one day in lenght. The sequences are located in the HEASARC MAXI data archive area in the /obs directory which is divided in 1000 days interval subdirectories named MJDdd000 (where dd000 correspond to the MJD of the start of the 1000 day). The sequences are located in the MJDddddd, where ddddd is the MJD day. The archive structure is therefore:

                MJD55000/  MJD56000/  MJD57000/  ...
                   MJD56000/ MJD56001/ MJD56002/ ....
                         auxil/     events/ 
                            gsc_med/ gsc_low/ ssc_med/

The directories gsc_med/ gsc_low/ ssc_med/ contains up to 768 event files where each is a specific region in the sky.

Archive access : Web, wget, download script and special maxi download script

At the HEASARC the MAXI archive can be accessed using the web interfaces Browse , the wget protocol, the download script or a special maxi script.

  • Access via Web : The archive access via the Web makes use of database table to search for the science data. The database table is maximaster which records high-level information for each MAXI region. One day observation contains up to 768 regions for the gsc_med/ gsc_low/ ssc_med/. This table can be queried for position, time and other parameters, and from the result page it is possible to select and retrieve the data files.
  • Wget : If you have wget installed, and the observation id is already known, the data can be retrieved via 'wget'. For example using the https protocol, if the user wants to retrieve the sequence 'MJD57002' observed in Dec 11 2014, she/he can retrive the entire sequence (see Example 1) or data for a single instrument (see Example 2)
    Example 1
     wget -q -nH --cut-dirs=5 -r -l0 -c -N -np -R 'index*' -erobots=off --retr-symlinks 
    Example 2
       wget -q -nH --cut-dirs=5 -r -l0 -c -N -np -R 'index*' -erobots=off --retr-symlinks 
  • download_wget : donwload_wget is a PERL script that uses the wget protocol, similarly to the example above, but simplify the command and allow for more flexility. You can retrive the download_wget and place it in your local machine
    Example: To download a specific sequence type: 
    > To get help type : > help
  • mxdownload_wget script : The script, also distributed with HEASoft MAXI package, allows to collect data for a given position in the sky within a time interval.
  • Example 1 :  Download all instruments data obtained between Sep 30 and Oct 1 of 2016 at the 
                 sky position R.A. 55.5 Dec 15.0. The chatter is set low. 
  --coordinates 55.5,15.0 --dates 2016-09-30,2016-10-01 --instruments all --chatter 2  
    Example 2 : List but do not download all files relevant to the time interval 
                Jan 1-2 2010 at the sky position R.A. 83.633083 Dec. 22.0145 
 -coordinates 83.633083, 22.0145 -date_from 2010-01-01 -date_to 2010-01-02 --dryrun