1. Site Surveys at HartRAO NERC Space Geodesy Facility, Herstmonceux ILRS Fall 2005 Workshop 3 October 2005 Ludwig Combrinck HartRAO Space Geodesy Programme

2. Footprints and Ties Outer network Outer network Intermediate network Intermediate network Inner network Inner network 2000 micro network 2000 micro network VLBI antenna offset VLBI antenna offset Ties between geodetic systems Ties between geodetic systems i.e. VLBI, SLR, GPS, DORIS i.e. VLBI, SLR, GPS, DORIS

3. Outer network for crustal stability

4. Intermediate Network

5. Inner network

6. Footprint network

7. More work

8. So a large team was sent to investigate

9. IGN/JPL/CDSM Survey July-August 2003

10. VLBI Antenna axis offset VLBI reference point is intersection of axes, or the projection point of the secondary axis onto the primary axis VLBI reference point is intersection of axes, or the projection point of the secondary axis onto the primary axis Axis offset determinations Axis offset determinations 1960 JPL engineering 6707 mm 1960 JPL engineering 6707 mm 1993 Conventional surveying 6695 +- 3 mm (Mark Newling, CDSM) 1993 Conventional surveying 6695 +- 3 mm (Mark Newling, CDSM) 1995 VLBI 6693.6 +-2.5 mm (Chopo Ma) 1995 VLBI 6693.6 +-2.5 mm (Chopo Ma) 1995 VLBI 6692.5 +- 1.5 mm (Marshall Eubanks) 1995 VLBI 6692.5 +- 1.5 mm (Marshall Eubanks) 1995 GPS 6695.6 +- 2.3 mm (Ludwig Combrinck) 1995 GPS 6695.6 +- 2.3 mm (Ludwig Combrinck) 1996 VLBI 6688.8 +- 1.8 mm (Chopo Ma) 1996 VLBI 6688.8 +- 1.8 mm (Chopo Ma) 2003 IGN 6695 +- 2.5 mm (IGN/JPL/CDSM) 2003 IGN 6695 +- 2.5 mm (IGN/JPL/CDSM)

11. 2003; Total stations

12. 2003 Method, TS and Matlab

13. GPS, own code

14. Typical Survey Pier

15. Repeatability? Different equipment (antennas etc) Different equipment (antennas etc) HRAO-SLR X Y Z (mm) HRAO-SLR X Y Z (mm) LC 1998 48554.3 65628.3 42835.7 LC 1998 48554.3 65628.3 42835.7 LC 1998 48552.2 65628.8 42837.1 LC 1998 48552.2 65628.8 42837.1 LC 1999 48556.2 65626.4 42834.7 LC 1999 48556.2 65626.4 42834.7 ITRF 2000 48619 65574 42797 ITRF 2000 48619 65574 42797 IGN 2003 48635.3 65591.8 42799.2 IGN 2003 48635.3 65591.8 42799.2 ~6.5cm ~4.5cm ~3.5cm ~6.5cm ~4.5cm ~3.5cm ~1.5cm ~1.5cm ~0.2cm ~1.5cm ~1.5cm ~0.2cm

16. Repeatability? Tie between VLBI and SLR Tie between VLBI and SLR X Y Z (M) X Y Z (M) ITRF 1993 41.634 -66.597 -8.169 ITRF 1993 41.634 -66.597 -8.169 ITRF 1994 41.652 -66.620 -8.187 ITRF 1994 41.652 -66.620 -8.187 GPS 1995 41.680 -66.564 -8.131 GPS 1995 41.680 -66.564 -8.131 ITRF 2000 41.672 -66.606 -8.135 ITRF 2000 41.672 -66.606 -8.135 IGN 2003 41.674 -66.596 -8.145 IGN 2003 41.674 -66.596 -8.145 ~8mm ~40mm ~4mm ~8mm ~40mm ~4mm ~2mm ~10mm ~10mm ~2mm ~10mm ~10mm

17. Conclusions Last survey closer to ITRF eccentricities Last survey closer to ITRF eccentricities Last word has not been spoken…… Last word has not been spoken……