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During the summer of 1984 five TI‐4100 global positioning system (GPS) receivers were used to measure an eight‐station network in Alaska and Canada, previously measured with mobile very long baseline interferometry (VLBI) systems, with baselines ranging from 300 km to almost 2700 km. The observations have been processed in the network mode with the Bernese GPS software using orbit improvement techniques. The comparisons of the GPS and VLBI solutions, established through a seven‐parameter Helmert transformation, show an agreement of the order of 0.1 ppm for all solutions. No significant scale factor between GPS and VLBI coordinates could be detected. These results demonstrate for the first time the power of orbit improvement in conjunction with network processing of GPS phase observations.

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Using artificial satellites as transfer objects the project “Coupled Quasar-Satellite-Star Positioning” represents an independent method for linking quasar and stellar reference frames. Optical observations of close approaches between reference stars and satellites yield satellite positions in the stellar reference frame. On the other hand high precision satellite orbits in the International Earth Rotation Service (IERS) terrestrial reference frame are obtained from laser or radiometric observations. Using IERS earth rotation parameters and adopted transformation models the satellite and eventually the star positions can be expressed in the IERS quasar celestial reference frame. In this paper we describe the CQSSP project and assess its capability for providing an accurate tie between tho two metioned celestial reference frames.