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   README.POLAR_B

   Author: Winston Teitler.

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   Documentation for the files of POLAR magnetic field B.

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 1) The files of POLAR B contain the magnetic field B in the GSM
    coordinate system.


    The data is at spin period time resolution, i.e., 1 data point every
    6 seconds (approximately).



 2) The time period covered by the data is:

        2001/01/01 - 2002/03/17



    Important Note:

    No calibration values for the magnetometer are presently available
    for the time period covered by the data.  Because of this,
    calibrations from 1 or 2 or 3 years previous on the same date have
    been used, when they are available.  Thus, the data contained in
    these files has not been certified by the magnetometer PI, and
    should not be regarded as definitive.





 3) The files of POLAR B are located on the ftp server

        polar2.ssl.berkeley.edu



    You need to log into this server via "anonymous ftp".

    If you are not allowed access to this site, please e-mail your IPO
    address, with a request to be added to the access list, to

        Jack Vernetti

        jackv@ssl.berkeley.edu

    so it can be added to the list of those allowed access.



    After logging into the server, you must go to the directory

        pub/polar/POLAR_B



    There are 2 sub-directories of this directory:

     1) ASCII

     2) CDF

    You must go to the sub-directory that corresponds to the data format
    you want (ASCII or CDF, respectively).  The data in both
    sub-directories is the same, the only difference is in the format.





 4) Underneath the ASCII sub-directory there are separate
    sub-directories for the data, by month.



    The name of each monthly sub-directory contains the number of the
    year, the number of the month, and the first 3 letters of the name
    of the month.

    The monthly sub-directories, then, are:

        2001_01_Jan, 2001_02_Feb, ..., 2002_03_Mar



    Within each monthly subdirectory, there are 3 files for each day;
    each file contains 1 component of the B vector.

    For example, the files for 2001/10/31 are:

        B_ASCII20011031.POLAR_B_A_12_GSM_X

        B_ASCII20011031.POLAR_B_A_12_GSM_Y

        B_ASCII20011031.POLAR_B_A_12_GSM_Z



    The ASCII files are plain text files.



    Each file contains a few comment lines at the beginning (7 lines)
    and at the end (3 lines).

    The comment lines are either empty lines, lines containing only
    "white space" (blanks and/or tabs), or lines that start with the
    "percent" character (%).



    Each line of data contains 3 columns:


     1) Data point index number.

        This is an integer.


     2) Time tag.

        This is a real number.

        Time tags indicate seconds elapsed since 0 hours UT of the day
        of the data file.


     3) Component of B.

        This is a real number.

        The components of B (X, Y, and Z respectively) are in units of
        nT.



    The ASCII files take up approximately 1.5 MB per day, or 45 MB per
    month; for a total of about 650 MB for the whole time interval.





 5) Underneath the CDF sub-directory there are separate sub-directories
    for the data, by month.



    The name of each monthly sub-directory contains the number of the
    year, the number of the month, and the first 3 letters of the name
    of the month.

    The monthly sub-directories, then, are:

        2001_01_Jan, 2001_02_Feb, ..., 2002_03_Mar



    Within each monthly subdirectory, there is 1 file for each day.

    For example, the file for 2001/10/31 is:

        B_CDF20011031.POLAR_B_A_12_GSM_X.cdf

    Note that, despite the "GSM_X" as part of the file name, each file
    contains the complete B vector (all 3 components), and of course
    the time tag as well.



    The CDF files are binary files.  Appropriate software is required to
    read them.



    The time tags and the units of the components of B are the same as
    for the ASCII files.



    The CDF files take up approximately 0.3 MB per day, or 9 MB per
    month; for a total of about 130 MB for the whole time interval.