Test of source selection for constructing a more stable and uniform celestial reference frame

Zhu, Zi

doi:10.1093/mnras/stw3156

Cited by 2 publications

(1 citation statement)

References 11 publications

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“…Based on these indicators, sources with an unstable position can be recognized and ruled out, leaving only stable sources to define and maintain the axes of the celestial reference frame, which are known as the defining sources (Feissel-Vernier 2003;Feissel-Vernier et al 2006;Lambert & Gontier 2009). The stability of the VLBI celestial reference frame can thus be improved when a proper ensemble of stable sources is used as the defining source subset (Arias & Bouquillon 2004;Liu et al 2017). A list of 303 sources with good astrometric behavior known as the ICRF3 defining sources was carefully selected, whose positions implicitly define the axes of the ICRF3 (Charlot et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the ICRF stability from a position time series analysis

Liu

Lambert

Arias

et al. 2022

A&A

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Context. The celestial reference frame is established on the basis of the absolute positions of extragalactic sources that are assumed to be fixed in space. The fixing of the axes is one of the crucial points for the concept behind the International Celestial Reference System (ICRS). However, due to various effects such as its intrinsic activity, the apparent position of the extragalactic sources may vary with time, resulting in a time-dependent deviation of the frame axes that are defined by the positions of these sources. Aims. We aim to evaluate the axis stability of the third realization of the International Celestial Reference Frame (ICRF3). Methods. We first derived the extragalactic source position time series from observations of very long baseline interferometry (VLBI) at the dual S∕X-band (2.3/8.4 GHz) between August 1979 and December 2020. We measured the stability of the ICRF3 axes in terms of the drift and scatter around the mean: (i) we estimated the global spin of the ICRF3 axes based on the apparent proper motion (slope of the position time series) of the defining sources of the ICRF3; (ii) we also constructed the yearly representations of the ICRF3 through annually averaged positions of the defining sources of the ICRF3 and estimated the dispersion in the axes orientation of these yearly frames. Results. The global spin is no higher than 0.8 μas yr-1 for each ICRF3 axis with an uncertainty of 0.3 μas yr-1, corresponding to an accumulated deformation smaller than 30 μas for the celestial frame axes during 1979.6–2021.0. The axes orientation of the yearly celestial frame becomes more stable as time elapses, with a standard deviation of 10 μas–20 μas for each axis. Conclusions. The axes of the ICRF3 are stable at approximately 10 μas–20 μas from 1979.6–2021.0 and the axes stability does not degrade after the adoption of the ICRF3.

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Section: Introductionmentioning

confidence: 99%

Evaluation of the ICRF stability from a position time series analysis

Liu

Lambert

Arias

et al. 2022

A&A

Self Cite

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Evaluation of the ICRF stability from position time series analysis

Liu,

Lambert,

Arias

et al. 2021

Preprint

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Context. The celestial reference frame is realized by absolute positions of extragalactic sources that are assumed to be fixed in the space. The fixing of the axes is one of the crucial points for the International Celestial Reference System (ICRS) concept. However, due to various effects such as its intrinsic activity, the apparent position of the extragalactic sources may vary with time, resulting in a time-dependent deviation of the frame axes that are defined by the positions of these sources. Aims. We aim to evaluate the axis stability of the third realization of the International Celestial Reference Frame (ICRF3). Methods. We first derive the extragalactic source position time series from observations of very long baseline interferometry (VLBI) at the dual S /X-band (2.3/8.4 GHz) between August 1979 and December 2020. We measure the stability of the ICRF3 axes in terms of the drift and scatter around the mean: (i) we estimate the global spin of the ICRF3 axes based on the apparent proper motion (slope of the position time series) of the ICRF3 defining sources; (ii) we also construct the yearly representations of the ICRF3 through annually averaged positions of the ICRF3 defining sources and estimate the dispersion in the axis orientation of these yearly frames. Results. The global spin is no higher than 0.8 µas yr −1 for each ICRF3 axis with an uncertainty of 0.3 µas yr −1 , corresponding to an accumulated deformation smaller than 30 µas for the celestial frame axes during 1979.6-2021.0. The axes orientation of the yearly celestial frame becomes more stable as time elapses, with a standard deviation of 10-20 µas for each axis. Conclusions. The axes of the ICRF3 are stable at approximately 10-20 µas from 1979.6-2021.0 and the axis stability does not degrade after the adoption of the ICRF3.

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Test of source selection for constructing a more stable and uniform celestial reference frame

Cited by 2 publications

References 11 publications

Evaluation of the ICRF stability from a position time series analysis

Evaluation of the ICRF stability from a position time series analysis

Evaluation of the ICRF stability from position time series analysis

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