************************************************************************ IERS Message No. 121 November 21, 2007 ************************************************************************ Information on the updates to the IERS Conventions The IERS Conventions Center provides the following information on the updates to the IERS Conventions. Chapter 9 "Troposheric model" of the IERS Conventions has been updated on 28 June 2007, see http://tai.bipm.org/iers/convupdt/convupdt_c9.html . This is a completely new version, with main contributions from J. Boehm, G. Hulley, A. Niell, E. Pavlis. For optical techniques, it describes a new model for the zenith delay and a new mapping function, both adopted by the ILRS as of 1 January 2007. For radio techniques, the VMF1 is now the recommended mapping function, which necessitates input coefficients determined from a numeric weather model. For users not aiming at the highest accuracy, the GMF, which uses standard input coefficients, is provided. Additional recent updates include Chapter 5: 2007/02/16: Revised section 5.8.3 to make the references for the planetary fundamental arguments clear. 2007/10/23: New section 5.4.6 on Free Core Nutation has been added, with subroutine provided by S. Lambert. Additional minor corrections in the text have been made to make the chapter's terminology consistent with the current IAU Recommendations. Chapter 7: 2007/06/20 and 2007/10/23: The Solid Earth tides subroutine dehanttideinel.f has been updated. See the IERS Message No. 87, March 16, 2006, http://www.iers.org/products/2/1262/orig/message_087.txt for more information on the Conventions updates web site. Gerard Petit and Brian Luzum IERS Conventions Center ************************************************************************ IERS Messages are edited and distributed by the IERS Central Bureau. To subscribe or unsubscribe, please write to . Archives: http://www.iers.org/iers/publications/messages/ ************************************************************************