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| Paper: |
Extending the ICRF to Higher Radio Frequencies: Astrometry at 24 and 42 GHz |
| Volume: |
340, Future Directions in High Resolution Astronomy: The 10th Anniversary of the VLBA |
| Page: |
523 |
| Authors: |
Jacobs, C.S.; Lanyi, G.E.; Naudet, C.J.; Sovers, O.J.; Zhang, L.D.; Charlot, P.; Gordon, D.; Ma, C. |
| Abstract: |
A program of survey observations using the Very Long Baseline Array (VLBA) at K-band (24 GHz) and Q-band (43 GHz) was begun in 2002 as a first step toward the goal of extending the ICRF to frequencies above 8.4 GHz. Each session covers the full range of right ascension and declinations down to ≈ −30 deg. Analysis of the first three sessions has produced a full sky catalog of 108 sources with median K-band formal position uncertainties of 210 and 280 μas in α cos(δ) and δ, respectively. For Q-band the corresponding results are 292 and 404 μas. Group delay residuals were excellent at ∼ 20 ps weighted RMS. An external comparison of the K-band frame to the S/X-band ICRF shows systematic errors at about 2 times larger than the formal precision. These systematic differences include a zonal trend vs. declination. We suspect that these errors are due in part to the North-South geometric weakness of the array. |
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