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    IERS Message: New release of the IAU SOFA software library
    From: Richard B. Langley
    Date: 2021 Feb 24, 13:00 -0800
    This message might be of interest to some NavList members.
    -- Richard Langley
    | Richard B. Langley                            E-mail: lang@unb.ca         |
    | Geodetic Research Laboratory                  Web: http://gge.unb.ca      |
    | Dept. of Geodesy and Geomatics Engineering    Phone:    +1 506 453-5142   |
    | University of New Brunswick                                               |
    | Fredericton, N.B., Canada  E3B 5A3                                        |
    |        Fredericton?  Where's that?  See: http://www.fredericton.ca/       |
    From: central_bureau@iers.org 
    Sent: February 24, 2021 12:52 PM
    To: messages@iers.org
    Subject: IERS Message No. 423: New release of the IAU SOFA software library
    ⚠External message: Use caution.
    IERS Message No. 423                                   February 24, 2021
    New release of the IAU SOFA software library
    The 17th Release of the SOFA (Standards of Fundamental Astronomy)
    Software Library was made available on 2021 January 25th at 14:00 UTC.
    This was a major release which implemented extra defensive precautions
    when computing refraction at low altitudes and the application of polar
    motion handling was changed to rigorous. Documentation was expanded,
    including a new cookbook for the SOFA Vector Matrix Library, and
    typographical and other minor corrections were applied. Changes were
    also made to the test programs for both distributions.
    A minor release (17a) for both the Fortran and ANSI C versions of
    Release 17 of the SOFA software library was made on 2021 February 24 at
    12:00 UTC. The change relates to the handling of leap seconds during the
    period 1960 and 1971. Between the introduction of UTC at the start of
    1960 and the first leap second at the end of 1971, there were a series
    of small offsets and rate changes with respect to TAI. The SOFA routine
    D2DTF takes these into account, but a shortcoming in the algorithm meant
    that under certain conditions a leap second could be flagged even though
    none had occurred. Such cases are extremely rare, and moreover, depended
    to some extent on compiler behaviour, affecting rounding.
    See the SOFA website at http://www.iausofa.org for the latest downloads
    and details of all changes.
    SOFA operates under the auspices of the International Astronomical Union
    (IAU) to provide algorithms and software for use in astronomical
    computing. The initiative is managed by an international panel, the SOFA
    Board, appointed through IAU Division A. The Board obtains the latest
    IAU-approved models and theories from the fundamental-astronomy
    community, implements them as computer code and checks them for
    accuracy. SOFA works closely with all the Commissions of the Division
    and with the International Earth Rotation and Reference Systems Service
    IERS Messages are edited and distributed by the IERS Central Bureau.
    If not stated otherwise, the IERS is only the distributor of the message
    and is not responsible for its content.
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