SCALE AND RATE : weighted average of the following VLBI and SLR solutions

• VLBI: GIUB, GSFC, SHA
• SLR: CGS, CRL, CSR, DGFI, JCET

ORIGIN (translations and rates) : weighted average of SLR solutions (CGS, CRL, CSR, DGFI, JCET)

ORIENTATION : insured upon a selection of ITRF sites with high geodetic quality

• Rotations: ITRF97 at 1997.0 epoch
• Rotation rates: No Net Rotation w.r.t. NNR-NUVEL1A

The criteria retained for site selection are :

• 1. Continuously observed during at least 3 years
• 2. Located on rigid plates and far away from deforming zones
• 3. Velocity formal error (as result of ITRF combination) better than 3 mm/y
• 4. Velocity residuals less than 3 mm/y for at least 3 different solutions

Based on the ITRF2000 preliminary analysis, sites selection was performed using the above criteria yielding 54 SITES shown in the following figure (blue dots).

This Figure shows also 41 SITES (red dots) satisfying 1, 3, 4 criteria.
Moreover, Bahrein (Arabian plate) and Easter Island (Nazca plate) are found to have estimated ITRF2000 velocities which disagree with NNR-NUVEL-1A by about 6 and 10 mm/, respectively. In addition, Tromsoe (Eurasian plate) and Flin-Flon (North American plate) show, respectively, about 2 mm/y post fit residual after absolute rotation poles estimation. Consequently, excluding these four sites, only 50 sites located on rigid plates were used in the ITRF2000 orientation rate definition.