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DTRF2008, a realization of the ITRSThe DTRF2008 (Seitz et al., 2012a) is a realization of the International Terrestrial Reference System ITRS. The DTRF2008 consists of station positions and velocities of global distributed observing stations of the space geodetic observation techniques VLBI, SLR, GPS and DORIS. The DTRF2008 was released in May 2010 and includes the observation data of the techniques up to and including 2008. The observation data are processed and submitted by the corresponding international services.
These services are: IGS (International GNSS Service) -> igscb.jpl.nasa.gov IVS (International VLBI Service) -> ivscc.gsfc.nasa.gov ILRS (International Laser Ranging Service) -> ilrs.gsfc.nasa.gov IDS (International DORIS Service) -> ids-doris.org
The DTRF2008 is an independent ITRS realization, which is computed on the basis of the same input data as the ITRF2008 (IGN, Paris) -> itrf.ensg.ign.fr/ITRF_solutions/2008/. The both realizations differ with respect to their computation strategies: while the ITRF2008 is based on the combination of solutions, the DTRF2008 is computed by the combination of normal equations (see Computation of global reference frames).
The DTRF2008 comprises the coordinates of 559 GPS-, 106 VLBI-, 122 SLR- and 132 DORIS-stations (see the figure). The reference epoch is 1.1.2005 UTC. The Earth Orientation Parameters (EOP) - that means the coordinates of the terrestrial and the celestial pole, UT1-UTC and the Length of Day (LOD) - were simultaneously estimated with the station coordinates. The EOP time series cover the period of 1983 to 2008. The station names are the official IERS indications: cdp numbers or 4-character IDs and DOMES numbers (http://itrf.ensg.ign.fr/doc_ITRF/iers_sta_list.txt). The solution is available in different file formats (SINEX and SSC) under ftp://www.dgfi.badw.de/pub/DTRF2008/ A detailed description of the solution is given by Seitz et al. (2012a). Seitz et al. (2010) gives a compact description of the solution in German. A very short description is also given in the SINEX files. The results of a comparison of DTRF2008 and ITRF2008 is given by Seitz et al. 2012(b). More information as well as residual time series of the station positions can be made available by request (contact: manuela.seitz @ dgfi.badw.de).
DTRF2008 and the IERS Conventions The DTRF2008 is based on the IERS Conventions 2003 (IERS TN 32). The input data are processed abiding these standards. The datum of DTRF2008 is also realized according to the Conventions. The Conventions, however, do not yet include a description of the strategy of combining normal equations. This approach is described inter alia by Angermann et al. (2009), Seitz (2009) and Seitz et al. (2012a).
ReferencesAngermann D., Seitz M., Drewes H.: Analysis of the DORIS Contributions to ITRF2008. Advances in Space Research 46, 1633-1647, doi:10.1016/.j.asr.2010.07.018, Elsevier, 2010 Seitz M., Angermann D., Bloßfeld M., Drewes H., Gerstl M.: The 2008 DGFI Realization of the ITRS: DTRF2008. J Geod, Volume 86, Issue 12, pp 1097-1123, DOI: 10.1007/s00190-012-0567-2, 2012 Seitz M., Angermann D., Drewes H.: Accuracy Assessment of ITRS 2008 Realization of DGFI: DTRF2008. Proceedings of the IAG Symposium REFAG2010, Springer (accepted), 2012(b) Seitz, M., D. Angermann, M. Bloßfeld, M. Gerstl, R. Heinkelmann, R. Kelm, H. Müller, Die Berechnung des Internationalen Terrestrischen Referenzrahmens ITRF 2008 am DGFI, zfv Zeitschrift für Geodäsie, Geoinformation und Landmanagement, 135, no. 2, 73-79, 2010. Seitz M.: Kombination geodätischer Raumbeobachtungsverfahren zur Realisierung eines terrestrischen Referenzsystems, Reihe C 630, Deutsche Geodätische Kommission, München, 2009, ISBN 978-3-7696-5042-6
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