Closure Traces: Novel Calibration-insensitive Quantities for Radio Astronomy

@article{Broderick2020ClosureTN,
  title={Closure Traces: Novel Calibration-insensitive Quantities for Radio Astronomy},
  author={Avery E. Broderick and Dominic W. Pesce},
  journal={The Astrophysical Journal},
  year={2020},
  volume={904}
}
Closure phases and closure amplitudes have proven critical to modern radio interferometry due to their insensitivity to the uncertain station gains. We present the first set of closure quantities constructed from parallel-hand and cross-hand visibilities that are insensitive to both station gains and to polarimetric leakage. These complex “closure traces” are a natural extension of closure amplitudes and closure phases, are independent of all station-based linear corruptions of the polarized… 

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References

SHOWING 1-10 OF 24 REFERENCES

Interferometry and Synthesis in Radio Astronomy

Preface to the Second Edition. Preface to the First Edition. Introduction and Historical Review. Introductory Theory of Interferometry and Synthesis Imaging. Analysis of the Interferometer Response.

MOJAVE: MONITORING OF JETS IN ACTIVE GALACTIC NUCLEI WITH VLBA EXPERIMENTS. V. MULTI-EPOCH VLBA IMAGES

We present images from a long-term program (MOJAVE: Monitoring of Jets in active galactic nuclei (AGNs) with VLBA Experiments) to survey the structure and evolution of parsec-scale jet phenomena

Closure Statistics in Interferometric Data

Interferometric visibilities, reflecting the complex correlations between signals recorded at antennas in an interferometric array, carry information about the angular structure of a distant source.

The structure of radio sources 3C 273B and 3C 84 deduced from the "closure" phases and visibility amplitudes observed with three-element interferometers.

The derived 'closure' phase relation for a three-element interferometer is used in a presented analysis of data obtained from observations at 7.8 GHz of the radio sources 3C 273B and 3C 84 by

ON THE MEASUREMENT OF POLARIZATION DISTRIBUTIONS OVER RADIO SOURCES

Abstract : A method for the determination of polarization distributions over radio sources by means of interferometric techniques is described. An expression is given for the response of an