The X/Ka Celestial Reference Frame: Results from combined NASA-ESA baselines
Abstract
We have constructed an X/Ka-band (8.4/32 GHz) celestial reference frame using over seventy ~24-hour sessions with the Deep Space Network. We detected 577 sources covering the full 24 hours of right ascension and the full range of declinations. Comparison of 447 X/Ka sources in common with the S/X-band (2.3/8.4 GHz) ICRF2 shows wRMS agreement of 200 micro-arcsec μas in RA cos(dec) and 270 μas in Dec. There is evidence for systematic errors at the 100 μas level. Known errors include limited SNR, lack of phase calibration, troposphere mismodelling. We have recently created a collaboration with ESA and their antenna in Malargüe, Argentina in order to improve our geometry in the south.
Compared to X-band, Ka-band allows access to more compact source morphology and reduced core shift. Existing X/Ka data and simulated Gaia data predict a frame tie precision of 10-15 μas (1-sigma, per 3-D rotation component) with anticipated improvements reducing that to 5-10 μas per component.- Publication:
-
Asia-Pacific Radio Astronomy Conference 2013
- Pub Date:
- September 2013
- Bibcode:
- 2013apra.confE...1H
- Keywords:
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- Celestial Reference Frame;
- astrometry;
- VLBI;
- quasar;
- AGN;
- interferometry;
- X/Ka-band