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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal><span lang=FR>Dear IGS, thanx for this opportunity.<o:p></o:p></span></p><p class=MsoNormal><span lang=FR><o:p> </o:p></span></p><p class=MsoNormal><span lang=FR><o:p> </o:p></span></p><p class=MsoNormal><span lang=FR>Dear Colleagues<span class=apple-converted-space> </span></span><o:p></o:p></p><p class=MsoNormal><span lang=FR> </span><o:p></o:p></p><p class=MsoNormal><span lang=FR>As you know the IAG Scientific Assembly will soon take place from 2021 June 28<sup>th</sup> to July 2<sup>nd</sup>.<span class=apple-converted-space> </span></span><o:p></o:p></p><p class=MsoNormal><span lang=FR>The website of the event is available at<span class=apple-converted-space> </span><span class=MsoHyperlink><span style='color:#0563C1'><a href="http://www.iag2021.com/en/web/index/"><span style='color:#954F72'>http://www.iag2021.com/en/web/index/</span></a></span></span><span class=apple-converted-space> </span>.</span><o:p></o:p></p><p class=MsoNormal><span lang=FR>The abstract submission deadline approaches quickly. It is April 30<sup>th</sup>.</span><o:p></o:p></p><p class=MsoNormal><span lang=FR>We, the session conveners of Session 1.5, would like to draw your attention to the session "Comparison and combination of space geodesy techniques for improving consistency between TRF, CRF and EOPs". The full session description is displayed below.</span><o:p></o:p></p><p class=MsoNormal><span lang=FR> </span><o:p></o:p></p><p class=MsoNormal><span lang=FR>We are looking forward receiving your abstracts and apologize for multiple postings.</span><o:p></o:p></p><p class=MsoNormal><span lang=FR> </span><o:p></o:p></p><p class=MsoNormal><span lang=FR>Best regards,</span><o:p></o:p></p><p class=MsoNormal><span lang=FR> </span><o:p></o:p></p><p class=MsoNormal><span lang=FR>Robert Heinkelmann, Chengli Huang, Zinovy Malkin and Manuela Seitz</span><o:p></o:p></p><p class=MsoNormal><span lang=FR>******</span><o:p></o:p></p><p class=MsoNormal><b>Symposium 1, Session 5</b><o:p></o:p></p><p class=MsoNormal><b>Comparison and combination of space geodesy techniques for improving consistency between TRF, CRF and EOPs</b><o:p></o:p></p><p class=MsoNormal>The international terrestrial and celestial reference frames, ITRF and ICRF, respectively, as well as the link between them expressed by the Earth Orientation Parameters (EOP) are key products of geodesy and astrometry. Many scientific and practical applications rely on the consistency of ITRF, ICRF, and EOP, and the requirements to all the components of this triad with respect to accuracy, precision and consistency grow steadily. Today, ITRF and ICRF are computed separately, but are linked by cross-alignments or by fixing parameters. While the ITRF and consistently estimated EOP series are derived from a combination of the four space geodetic techniques VLBI, SLR, GNSS and DORIS, the ICRF and the related EOP series are derived from VLBI observations only. To reach a high consistency between the products, the homogeneity of geophysical and astronomical models, of geodetic datum, and of parameterization is necessary. The topics discussed in this session will include the comparison and combination of EOP and TRF solutions derived by different techniques, as well as comparison of VLBI-only and multi-technique CRF realizations including assessing and understanding the systematic differences between them, and their impact on EOP estimates. A further important discussion topic will be issues<span class=apple-converted-space> </span>currently preventing the realization of the terrestrial and celestial reference systems at the mm/μas level of<span class=apple-converted-space> </span>accuracy, such as deficiencies of the station network including station instabilities, technological (precision) limitations of existing techniques, incompleteness of the theory and models, not fully understood and agreed-upon details of the processing strategy, and others. The session solicits contributions to all these topics.<o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal>This session solicits contributions focusing on the following aspects:<o:p></o:p></p><p class=MsoNormal style='text-indent:-18.0pt'><span style='font-family:Symbol'>·</span><span style='font-size:7.0pt'> <span class=apple-converted-space> </span></span>Comparison and combination of EOP solutions by different techniques.<o:p></o:p></p><p class=MsoNormal style='text-indent:-18.0pt'><span style='font-family:Symbol'>·</span><span style='font-size:7.0pt'> <span class=apple-converted-space> </span></span>Comparison and combination of TRF solutions derived by different techniques.<o:p></o:p></p><p class=MsoNormal style='text-indent:-18.0pt'><span style='font-family:Symbol'>·</span><span style='font-size:7.0pt'> <span class=apple-converted-space> </span></span>Comparison of VLBI-based and combined multi-technique CRF realizations.<o:p></o:p></p><p class=MsoNormal style='text-indent:-18.0pt'><span style='font-family:Symbol'>·</span><span style='font-size:7.0pt'> <span class=apple-converted-space> </span></span>Unification of astronomical and geophysical modeling.<o:p></o:p></p><p class=MsoNormal><b> </b><o:p></o:p></p><p class=MsoNormal><b>Keywords:<span class=apple-converted-space> </span></b>Terrestrial Reference Frame (TRF), Celestial Reference Frame (CRF), Earth Orientation Parameters (EOPs), space geodetic techniques, VLBI, multi-technique CRF realization.<o:p></o:p></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman",serif'><o:p> </o:p></span></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Dr. Robert Heinkelmann<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Dept.1: Geodesy<o:p></o:p></p><p class=MsoNormal>Sect.1: Space Geodetic Techniques<o:p></o:p></p><p class=MsoNormal>Tel.: +49 (0)331/288-1144<o:p></o:p></p><p class=MsoNormal>Fax: +49 (0)331/288-1111<o:p></o:p></p><p class=MsoNormal>E-Mail: heinkelmann@gfz-potsdam.de<o:p></o:p></p><p class=MsoNormal>____________________________________<o:p></o:p></p><p class=MsoNormal>Helmholtz Centre Potsdam<o:p></o:p></p><p class=MsoNormal>German Research Centre for Geosciences GFZ<o:p></o:p></p><p class=MsoNormal><span lang=DE>Stiftung des öff. Rechts Land Brandenburg<o:p></o:p></span></p><p class=MsoNormal><span lang=DE>Telegrafenberg, 14473 Potsdam<o:p></o:p></span></p><p class=MsoNormal><span lang=DE><o:p> </o:p></span></p><p class=MsoNormal><span lang=DE>IERS Analysis Coordinator<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>