Subject: IAU SOFA initiative

From: [email-masked] (Pat Wallace)
Date: 8 Dec 1995 08:30:48 -0600

The IAU's Working Group on Astronomical Standards (WGAS) is inviting
applications for positions on the Board of Review for its Standards
Of Fundamental Astronomy initiative (SOFA).

SOFA will provide:

  * A set of basic software which implement commonly-used formulae
    and standard models in fundamental astronomy.

  * Lists of constants and astronomical quantities, all accessible
    electronically.

The SOFA management arrangements include a Maintenance Committee for
Constants and Best Estimates, a Board of Review for Procedures (the
subject of this invitation) and a Relativity Subgroup.  Further details
are given in the Appendix, below.

The SOFA Board of Review will decide which standard algorithms should be
provided and in what form.  The key algorithms - for example procedures
for generating precession and nutation matrices - will have a canonical
status and their production will require great care and circumspection.
The rate at which new procedures are added to SOFA will consequently be
quite modest, just a few per year.

The Review Board will face many interesting questions.  What functions
should be included?  Should practical software be provided, or is
specimen code preferable?  How many variants should be provided
(e.g. different precession models)?  How hard a line on programming
style should be taken?  What languages will be accepted?  What degree
of granularity and orthogonality will be best?  What will be the
approach to error checking?  Who will write the software?  Who will
provide support?  Who will assess the software?  Will SOFA include
information about proprietary software?

If you would like to serve as a member of the SOFA Reviewing Board (and
can obtain support from your institution to participate), or if you would
be prepared to act as a reviewer, please contact me before 1996 February 1.

Patrick Wallace,
Starlink Project,
Rutherford Appleton Laboratory,
Chilton, Didcot, Oxon OX11 0QX
United Kingdom

tel +44 1235 445372
fax +44 1235 445848
Email [email-masked]

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APPENDIX

At the 1994 General Assembly, the IAU passed Resolution B11, proposed
by Division 1's Working Group on Astronomical Standards (in which
Commissions 4, 5, 8, 19, 24 & 31 participate) during Joint Discussion 14.
The full wording of the resolution is:

     "The XXIInd General Assembly of the International Astronomical Union

     CONSIDERING that the interchangeability of observational data,
     whether processed or not, requires the widespread use of a common
     set of constants and algorithms that implement standard models used
     in fundamental astronomy,

     RECOMMENDS that

     1) the IAU Working Group on Astronomical Standards continue
        permanently and assume the responsibility for establishing and
        maintaining a set of constants, algorithms, and procedures,

     2) the IAU WGAS identify single center at a suitable institution,
        under a worldwide reviewing board, to organize, maintain, and
        distribute electronically the set of constants, algorithms,
        and procedures, and

     3) the Center, and the IAU WGAS coordinate their activities with
        the IERS and the IAG."

The SOFA service, which implements this resolution, will comprise:

  * A set of basic software which implement commonly-used formulae
    and standard models in fundamental astronomy.

  * Lists of constants and astronomical quantities, all accessible
    electronically.

The supporting management structures that are being established are as
follows:

  * The MAINTENANCE COMMITTEE, which will

    Establish a revision mechanism.

    Continuously revise the "best estimates" of various quantities.

    Discuss possible revisions of astronomical constants (especially
    the precession constant).

    Assess possibilities for coordination with other fundamental-
    astronomy and geodesy activities (e.g. IERS, IAG).

  * The REVIEWING BOARD, which will comprise about 8 members plus a
    panel of reviewers, initially will

    Invite bids for the IAU/SOFA Center.

    Assess the bids and nominate a Center.

    Start reviewing algorithms, procedures and software.

  * The SUBGROUP ON RELATIVISTIC ISSUES, which will

    Discuss the definitions of units and certain astronomical
    constants within the framework of General Relativity.

  * The DISTRIBUTION CENTER, which will

    Operate the service, principally through various electronic
    channels.

The terms of office of the various bodies will formally be from one
IAU General Assembly to the next.  The current Chairs are:

  D.D.McCarthy (USA, USNO)        Maintainance Committee
  P.T.Wallace  (UK, Starlink)     Board of Review
  V.A.Brumberg (Russia, IAA)      Subgroup on Relativity

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