************************************************************************ IERS Message No. 142 February 16, 2009 ************************************************************************ Information on the updates to the IERS Conventions The IERS Conventions Center provides the following information on the updates to the IERS Conventions since IERS Message No. 139 (December 05, 2008). Chapter 7 "Displacement of reference points" has been updated on 10 February 2009, see http://tai.bipm.org/iers/convupdt/convupdt_c7.html: The section 7.2 "Models for the displacement of reference points of instruments" has been updated. It now contains models for a reference temperature (provided by J. Boehm), the thermal expansion of VLBI antennas (provided by A. Nothnagel) and GNSS antenna phase center offsets and variations (provided by R. Schmid). Each sub-section is intended to be a short presentation with links to other sites providing more complete information. The subroutine hardisp.f that computes the displacement due to ocean tidal loading has been updated by D. Agnew, following reports of a sign error in the long-period tides. The number of harmonics used and the internal precision have also been increased. Numerous typos have been corrected and other stylistic corrections introduced to the chapter, following remarks by R. Schmid. Chapter 9 "Models for propagation delays" has been updated on 12 February 2009, see http://tai.bipm.org/iers/convupdt/convupdt_c9.html . It now includes a new section "Ionospheric models for radio techniques", written by M. Hernandez Pajares with contributions by U. Hugentobler, F. Mercier and others. The title of the chapter has been changed accordingly (past title was "Tropospheric model"). 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/ ************************************************************************