0000000000658933
AUTHOR
S. Jiménez-monferrer
Atmospheric turbulence in phase-referenced and wide-field interferometric images
Phase referencing is a standard calibration procedure in radio interferometry. It allows us to detect weak sources by using quasisimultaneous observations of closeby sources acting as calibrators. However, atmospheric turbulence may introduce strong differences in the optical paths of the signals of the target and calibrator and affect, or even waste, phase referencing in cases of relatively large calibrator-to-target separations and/or bad weather. The situation is similar in wide-field interferometric observations. We present the results of a Monte Carlo study of the astrometric precision and sensitivity of an interferometric array (a realization of the Square Kilometre Array, SKA) in pha…
The AB Doradus System Revisited: The Dynamical Mass of AB Dor A
International audience; We report new radio interferometric observations of the quadruple pre-main-sequence (PMS) system ABD oradus. From these observations, combined with existing VLT near-infrared relative astrometry, we have refined the estimates of the dynamical masses of the system. In particular, we find component masses of 0.86 ± 0.09M&sun; and 0.090 ± 0.003M&sun; for ABD or A and ABD or C, respectively. These dynamical masses, coupled with temperatures and luminosities, allow for comparison with theoretical stellar models. The case of ABDorC, in terms of calibration of evolutionary models of low-mass young stars has been widely reported in previous studies. In this contribution, we …
Coherence loss in phase-referenced VLBI observations (Corrigendum)
fat = K ν √ Δt sin θ, (2) where K ∼ 0.012 h0.5 GHz−1. This new equation implies a different value of the constant k1 in Eq. (4). The original value reported for k1 was ∼63, while the correct value is ∼1.3 × 104. Although Eq. (3) (together with the constants K and k1) was incorrectly written in the text, we emphasize that all the figures in the paper were generated, indeed, using the correct equations and constants.
Coherence loss in phase-referenced VLBI observations
Context. Phase-referencing is a standard calibration technique in radio interferometry, particularly suited for the detection of weak sources close to the sensitivity limits of the interferometers. However, effects from a changing atmosphere and inaccuracies in the correlator model may affect the phase-referenced images, and lead to wrong estimates of source flux densities and positions. A systematic observational study of signal decoherence in phase-referencing and its effects in the image plane has not been performed yet. Aims. We systematically studied how the signal coherence in Very-Long-Baseline-Interferometry (VLBI) observations is affected by a phase-reference calibration at differe…