1. D. S. MacMillan 16-April-2008 Modeling Phase and Cable Cal for ONSALA60 Dan MacMillan NVI/NASA/GSFC Per Bjerkeli Chalmers University, Sweden Modeling Phase and Cable Cal for ONSALA60 Dan MacMillan NVI/NASA/GSFC Per Bjerkeli Chalmers University, Sweden

2. D. S. MacMillan 16-April-2008 Overview The RDV experiments (6 per year) use the 10 station VLBA network plus 9-10 of our geodetic antennas. Currently phase cal is not available at the correlator for the non-VLBA antenna Dependence of cable delays on the direction that an antenna is observing => Bias in estimated station coordinates The cable wrapping at Onsala causes cable stretching that varies ~linearly with azimuth => 10-12 mm bias if cable cal is applied with no phasecal.

3. D. S. MacMillan 16-April-2008 Onsala Phasecal Group and Cable Delay Phasecal group delay (10 -11 sec) vs. azimuth from a year of Europe sessions Cable delay (10 -11 sec) vs. azimuth from a year of Europe sessions

4. D. S. MacMillan 16-April-2008 BaselineNo Cable Applied Model 1Model 2 (mm) Gilcreek - Onsala11.68.86.9 Medicina - Onsala-8.9-3.9-3.5 NyAlesund - Onsala7.43.31.9 Wettzell - Onsala-7.5-2.8-2.2 Matera - Onsala-9.7-3.9-4.4 Hartrao - Onsala-6.7-1.2-3.9 Bias of RDV Onsala Baseline Lengths (Relative to Trend of All Other Sessions) Model 1 : Phase Cal = 2 * Cable Cal Model 2 : Azimuth/Temperature dependent models for Phase Cal and Cable Cal

5. D. S. MacMillan 16-April-2008 Correcting the radio source group delay with the phase cal group delay will overcorrect by –τ pc. Cable cal correction = + τ pc If there is no phase cal then assume that the phase cal and IF cable delays are the same => Correction = - τ pc Instrumental group delay for the radio source Instrumental group delay for phase cal

6. D. S. MacMillan 16-April-2008 ( ϕ < π ) ( ϕ > π ) Phase Cal and Cable Cal Models A year of EUROPE sessions (Jan. 2001 to Feb. 2002) were analyzed Cable cal and Phase cal were extracted and fit with functions of azimuth, temperature, and elevation where ϕ is azimuth and ε is elevation and T is temperature.

7. D. S. MacMillan 16-April-2008 a-coefficients for cable cal model as a function of temperature. a1 a2

8. D. S. MacMillan 16-April-2008 a-coefficients for phase cal model as a function of temperature. a1 a2