A spherical-harmonic fit to a million quasar parallaxes yields a sky-map correction tool for Gaia DR3, revealing a dipole-like pattern and showing the zero-point leaks into proper motions.
On significance of VLBI/Gaia position offsets
1 Pith paper cite this work. Polarity classification is still indexing.
1
Pith paper citing it
abstract
We have cross matched the Gaia Data Release 1 secondary dataset that contains positions of 1.14 billion objects against the most complete to date catalogue of VLBI positions of 11.4 thousand sources, almost exclusively active galactic nuclei. We found 6,064 matches, i.e. 53% radio objects. The median uncertainty of VLBI positions is a factor of 4 smaller than the median uncertainties of their optical counterparts. Our analysis shows that the distribution of normalized arc lengths significantly deviates from Rayleigh shape with an excess of objects with small normalized arc lengths and with a number of outliers. We found that 6% matches have radio optical offsets significant at 99% confidence level. Therefore, we conclude there exists a population of objects with genuine offsets between centroids of radio and optical emission.
fields
astro-ph.GA 1years
2026 1verdicts
CONDITIONAL 1representative citing papers
citing papers explorer
-
Gaia parallax bias via spherical harmonics: A Python tool and discussion of possible causes
A spherical-harmonic fit to a million quasar parallaxes yields a sky-map correction tool for Gaia DR3, revealing a dipole-like pattern and showing the zero-point leaks into proper motions.