Towards a robust estimation of orientation parameters between ICRF and $Gaia$ celestial reference frames. (arXiv:2107.08967v1 [astro-ph.IM])

Towards a robust estimation of orientation parameters between ICRF and $Gaia$ celestial reference frames. (arXiv:2107.08967v1 [astro-ph.IM])
<a href="http://arxiv.org/find/astro-ph/1/au:+Malkin_Z/0/1/0/all/0/1">Zinovy Malkin</a>

An analysis of the source position differences between VLBI-based ICRF and
$Gaia$-CRF catalogues is a key step in assessing their systematic errors and
determining their mutual orientation. One of the main factors that limits the
accuracy of determination of the orientation parameters between two frames is
the impact of outliers. To mitigate this effect, a new method is proposed based
on pixelization data over the equal-area cells, followed by median filtering of
the data in each cell. After this, a new data set is formed, consisting of data
points near-uniformly distributed over the sphere. The vector spherical
harmonics (VSH) decomposition is then applied to this data to finally compute
the orientation parameters between ICRF and $Gaia$ frames. To validate the
proposed approach, a comparison was made of the ICRF3-SX and $Gaia$~DR2
catalogues using several methods for outliers removal. The results of this work
showed that the proposed method is practically insensitive to outliers and thus
provides much more robust results of catalogues comparison than the methods
used so far. This conclusion was confirmed by analogous test comparison of the
$Gaia$~DR2 and OCARS catalogues.

An analysis of the source position differences between VLBI-based ICRF and
$Gaia$-CRF catalogues is a key step in assessing their systematic errors and
determining their mutual orientation. One of the main factors that limits the
accuracy of determination of the orientation parameters between two frames is
the impact of outliers. To mitigate this effect, a new method is proposed based
on pixelization data over the equal-area cells, followed by median filtering of
the data in each cell. After this, a new data set is formed, consisting of data
points near-uniformly distributed over the sphere. The vector spherical
harmonics (VSH) decomposition is then applied to this data to finally compute
the orientation parameters between ICRF and $Gaia$ frames. To validate the
proposed approach, a comparison was made of the ICRF3-SX and $Gaia$~DR2
catalogues using several methods for outliers removal. The results of this work
showed that the proposed method is practically insensitive to outliers and thus
provides much more robust results of catalogues comparison than the methods
used so far. This conclusion was confirmed by analogous test comparison of the
$Gaia$~DR2 and OCARS catalogues.

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