Thread: (CMPAZ) SAC header problem

Started: 2021-03-24 08:31:19
Last activity: 2021-03-25 17:05:27
Topics: SAC Help
Hitesh Majhi
2021-03-24 08:31:19
How header CMPAZ is different from BAZ and AZ ? If CMPAZ header is missing from sac file then how to calculate it and input this obtain value?
  • Arthur Snoke
    2021-03-25 17:05:27
    On 3/25/21 12:43 PM, Hitesh Majhi (via IRIS) wrote:
    How header CMPAZ is different from BAZ and AZ ? If CMPAZ header is missing from sac file then how to calculate it and input this obtain value?
    These terms are defined in the manual file Sac Data File format:
    http://ds.iris.edu/files/sac-manual/manual/file_format.html

    CMPAZ is Component azimuth (degrees clockwise from north).  If it is missing,
    either SAC does not know about the station latitude and longitude or the
    orientation of the component for that record is unknown (to SAC).

    AZ and BAZ are defined using the locations of the station and event.  One needs
    both locations.

    A technique I use to find information about a term (like CMPAZ) is to go to the
    SAC manual page on the IRIS server at http://ds.iris.edu/files/sac-manual/ and
    then click on the PDF SAC Manual
    (http://ds.iris.edu/files/sac-manual/sac_manual.pdf).  I recently discovered
    that in CHROME (but not in SAFARI). there is a prompt asking if one wanted to
    open the file in Acrobat.  I suggest doing it, as one gets much more information
    for searching, etc., in Acrobat.  I then do a "find" for the term.  I am going
    into this detail because I realized a while ago that when I made the PDF manual,
    I accidentally left out the SAC Data File Format file, and have not gotten
    around to updating the manual on the IRIS server. That fie is in the HTML
    version, but as it is relevant to the question asked I included the link.

    I found a typo when I did my search today.  Please share any other typos, etc.
    and I will include them when I correct the manual on the IRIS server.

    Arthur

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