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SPDF

CDF Leap Second Table

The leap second table has been modified as a new second is added on 01-01-2017. Please update the CDF to the latest version: V3.6.4.0. This version, not only has the new leap second table and related code changes for it, but also contains the bug fixes and other enhancements. Users that create and access CDF files that may contain TT2000 data should have their CDF version upgraded.

For all data producers, including IDL, MATLAB, etc, users, you should upgrade to the latest release based on CDF V3.6.4.0 now.

For those users that only read the CDF files, you are strongly encouraged to upgrade the software/patch version now. If you want to delay upgrading the software/patch version at this moment, this is the new Leap Second Table that should be used. Make sure that one of the following environment variables is set:

  • CDF_LEAPSECONDSTABLE (for non-VMS system), or
  • CDF$LEAPSECONDSTABLE (for VMS systems)
It should point to the new leap second table.

If the CDF file was made with older CDF version and leap second table, it might be rejected by the CDF's sanity check if its data has any TT2000 time later than 1/1/2017. To read the file, you need to have to set another environment variable:

  • CDF_VALIDATE (for non-VMS system) or
  • CDF$VALIDATE (for VMS systems)
to "no".

In the distributed source or pre-built package, there is a command-line based tool program that can be used to check where the leap second table is and how it is being used. IDL and MATLAB also has a similar module.

  • For Linux/Unix/MacOSX/Windows: use the command line tool: cdfleapsecondsinfo. Run:

    cdfleapsecondsinfo -nodump

    it will show whether an external table or a hard-coded table in the library is used, and when the last leap second is added.

  • For IDL, use cdf_leapseconds_info module to get the leap second table information.

    info=CDF_LEAPSECONDS_INFO()

    The tags: USE_FILE, CDF_LEAPSECONDSTABLE and LASTUPDATED from the info structurfe will have the relevant information.

  • For MATLAB, use spdfcdfleapsecondsinfo module to get the leap second table information. Run:

    spdfcdfleapsecondsinfo('dump', false).

    If you have any question or need assistance, please contact us at gsfc-cdf-support@lists.nasa.gov .