On the most reliable value of the Galactic aberration constant

TL;DR

This paper investigates the Galactic aberration constant, a small but significant effect in celestial proper motions, by comparing astrometric data with stellar astronomy methods to resolve discrepancies between VLBI and Gaia estimates.

Contribution

It introduces an independent method using stellar astronomy to estimate the Galactic aberration constant, addressing inconsistencies in previous measurements.

Findings

GA constant estimate from stellar astronomy aligns more closely with Gaia data

The method provides an alternative approach to determine the GA constant

Results help improve the accuracy of celestial proper motion corrections

Abstract

Galactic aberration (GA) is a small effect in proper motions of celestial objects with an amplitude of about 5 $\mu$as/yr already noticeable in highly accurate astrometric observations such as VLBI and Gaia. However accurate accounting for this effect faces difficulty caused by the uncertainty in the GA amplitude (GA constant). Its estimates derived from VLBI and Gaia data processing differ significantly, so it would be very desirable to involve another independent method to solve the problem of inconsistency between these two methods. Such a method, that we consider in this paper, is using determination of the Galactic rotation parameters by methods of stellar astronomy. The result obtained in this study showed that the GA constant estimate obtained from stellar astronomy is closer to the estimate obtained from Gaia.