IGS Analysis Center Workshop - IGS - NASA

within a few monthsThe IGS orbit products will be based, at least in the initial stages, on the weighted averagecombination method as outlined in the position paper and the second method, the orbital dynamicsmethod, will be used for preanalysis and evaluation using multi-day arcs. Individual Center orbitseries will continue to be archived and made available by IGS.The Analysis Center coordinator responsible for generation of the IGS combined orbit isencouraged to provide useful and timely feedback to contributing Centers as well as to stimulatefurther research at other Centers to encourage future improvements.3) IGS PROCESSING STANDARDSFirst task is to gather information on Analysis Center models, estimation strategy, coordinates, etc.CB (Blewitt and Zumberge) will develop an electronic questionnaire to be filled out by AnalysisCenters. Completed questionnaires will be made available to all Centers, IGN/IERS, and will beavailable cm the IGS Information system being implemented at the Central Bureau. This way thedifferences and changes of estimation strategies and how this relates to solution differences will besystematically documented.All Centers agreed in principle to adopt the same set of fiducial coordinates for purposes of orbit/EOP products. The proposed list of stations is as above, in Session 1.It is recommended that the January orbit test reprocessing (weeks 680 and 681) be completed bythe Centers which have not done so yet, or which want to reprocess it again with improved(changed) orbit estimation strategies. For this reprocessing, the IGS Mail message 263 will be thestandard for monument coordinates and antenna heights.4) INTEGRATION OF REGIONAL STATION CLUSTERSUsing the IGS (combined) orbits is the simplest form of distributed processing thus should beimplemented immediately to accommodate various regional processing.Distributed processing should imply only minimal computational increase for the IGS ‘AnalysisCenter. Reduced normals (’fiducial-free’) contribution from IGS Analysis Centers will benecessary in the future distributed processing and all Centers are encouraged to develop thiscapability as soon as possibleAdditional products, such as tropospheric calibration delays may also be useful for distributedprocessing also more research is needed for distributed processing strategies (e.g. the effect andmitigation of data overlaps (using data more than once)).101