Thread: Shifting Reference Time

Started: 2023-01-18 19:35:04
Last activity: 2023-01-26 17:53:03
Topics: SAC Help
アングライニノビア
2023-01-18 19:35:04
Good Afternoon
My SAC data is in UT and I need to change it to GMT+4.
At first, I used the chnhdr+wh command, but it only changed the header, as
its name suggests, but when I plotted the data, the X axis started from
-14400, 4*3600.
Is there any other way to shift the time reference of SAC data, so that
when I plot it the data will start from 0 s?
I really appreciate any help you can provide

  • George Helffrich
    2023-01-26 17:53:03
    Dear Novia Anggraini -

    Use the SYNCHRONIZE command in SAC to make your traces start with 0.

    SAC expects time to be in GMT, so you probably don’t want to change the zero time in the file to a different time zone. If for some reason you do need to change the time reference, see the ALLT option of the CHNHDR command.

    SYNCHRONIZE probably will do what you want.

    On 26 Jan 2023, at 17:00, アングライニノビア (via IRIS) <sac-help-bounce<at>lists.ds.iris.edu> wrote:

    Good Afternoon
    My SAC data is in UT and I need to change it to GMT+4.
    At first, I used the chnhdr+wh command, but it only changed the header, as its name suggests, but when I plotted the data, the X axis started from -14400, 4*3600.
    Is there any other way to shift the time reference of SAC data, so that when I plot it the data will start from 0 s?
    I really appreciate any help you can provide

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    George Helffrich
    george<at>elsi.jp


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