Very Long Baseline Interferometry and the VLBAASP
نویسندگان
چکیده
Phase-referencing allows phase calibration of VLBI data. Using regular observations of a nearby calibrator source, delay, delay-rate, and phase corrections can be derived and their eeects removed from the target source visibility data. This technique allows imaging much weaker objects than is possible via fringe-tting methods. We examine the main types of phase error in VLBI observations (geometrical, instrumental, atmospheric, and ionospheric errors), and we demonstrate how phase-referencing reduces or removes them. Maximum switching times and angles, and the image dynamic ranges and sensitivities achievable using phase-referencing are discussed.
منابع مشابه
Very Long Baseline Interferometry and the VLBAASP
The special problems encountered when performing spectral-line VLBI observations are discussed in this Chapter. In particular, the usefulness of Fourier transforming measured visibility data with respect to time, delay or frequency for purposes of fringe detection and calibration is clariied.
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