DGFI as one of the ITRS Combination Centres of International Earth Rotation and Reference System Service (IERS) has completed the computation of the International Terrestrial Reference Frame 2008 (ITRF2008D). ITRF2008D is an independent solution, based on the same input data as ITRF2008, which is computed by the IERS Combination Centre at IGN, Paris, and provided by the IERS Product Centre at IGN in May 2010. The difference between both solutions is the combination strategy: while a combination of solutions is performed at IGN, DGFI computation is based on the combination of normal equations.

The ITRF2008D is a global terrestrial reference frame containing the station coordinates of 559 GPS, 106 VLBI, 122 SLR and 132 DORIS stations. The reference epoch for station positions is 2005-01-01, 0:00 UTC. Earth orientation parameters (EOP), i.e., coordinates of the terrestrial and the celestial pole, UT1-UTC and length of day (LOD), are simultaneously solved with the station coordinates. The time series of EOP covers the period from 1983 until the end of 2008. The solution is available in different file formats at ftp.dgfi.badw.de/pub/ITRF2008D. A short description of the solution is given in the local SINEX file.

On 17 March 2010 ESA's satellite GOCE celebrated its first birthday. GOCE was launched on 17 March 2009, 15:21 CET, from Plestsk, Russia. The aim of GOCE is to determine the Earth's stationary gravity field with unprecedented accuracy up to a spatial resolution of about 100 km. In order to do so, GOCE is in a very low orbit, about 260 km altitude, and carries a gravity gradiometer that allows the measurement of the second spatial derivatives of the gravitational potential. Since Autumn 2009, GOCE delivers scientific data and DGFI is involved in the calibration of the gradiometer data in collaboration with IAPG (TUM). When enough GOCE data are available, we want to use these, among others, for regional gravity field determination and combination with satellite altimeter data for improved modelling of the mean dynamic ocean topography.

For further information on GOCE see: www.esa.int/SPECIALS/GOCE/index.html

To estimate the impact of the Chile earthquake in the Reference Frame for the Americas (SIRGAS), the SIRGAS Analysis Centre at DGFI estimated daily station positions between February 21 and March 6, 2010, for selected continuously operating SIRGAS stations. Results show that the GPS station CONZ (Concepción, Chile) initially moved 2,9 m in the south-west direction (on 27-02-2010). In the week following the first earthquake, post-seismic movements of more than 10 cm were detected. Additional GPS stations located between latitudes 30°S to 40°S from the Pacific to the Atlantic coast also present larger displacements. [More]

The free oscillations of the Earth caused by the displacement from the position of rest will be excited by earthquakes with a magnitude larger than 6.5 on the momentum scale. After the huge Offshore Maule earthquake in Chile on Februar 27, 2010 with magnitude 8.8 on the momentum scale the free oscillations were excited.

The frequency domain of free oscillations is between 0.3 mHz, i.e. a period of 54 minutes and 20mHz i.e. a period of 50 seconds. [More]