Astrometry in crowded fields towards the Galactic Bulge

Understand

The astrometry towards the Galactic Bulge is hampered by high stellar crowding and patchy extinction.

• This effect is particularly severe for optical surveys such as Gaia.
• In this study, we assess the consistency of proper motions (PMs) between optical (Gaia DR3) and near-infrared (VIRAC2) catalogues in comparison with PMs measured with the Hubble Space Telescope (HST) in several crowded fields towards the Galactic Bulge and in Galactic globular clusters.
• Assuming that the PMs are well characterised, the uncertainty-normalised PM differences between pairs of catalogues are expected to follow a normal distribution.