Related papers: Gaia Data Release 2: The Celestial reference frame…
The recently published Gaia DR3 catalog of 181327 spectroscopic binaries (SB) includes the Keplerian elements of each orbit but not the measured radial velocities (RVs) and their epochs. Instead, the catalog lists a few parameters that…
We present and analyse mock stellar catalogues that match the selection criteria and observables (including uncertainties) of the Gaia satellite data release 2 (DR2). The source are six cosmological high-resolution magneto-hydrodynamic…
Previous studies based on the latest realisation of the International Celestial Reference Frame (ICRF3) have suggested a correlation between astrometric properties (such as the radio-optical offset) and redshift for active galactic nuclei…
The early third data release (EDR3) of the European Space Agency satellite Gaia provides coordinates, parallaxes, and proper motions for ~1.47 billion sources in our Milky Way, based on 34 months of observations. The combination of Gaia DR2…
Astrometric microlensing is a unique tool to measure stellar masses. It allows us to determine the mass of the lensing star with an accuracy of a few per cent. In this paper, we update, extend, and refine our predictions of…
We have analyzed the differences in positions of 9081 matched sources between the Gaia DR2 and VLBI catalogues. The median position uncertainty of matched sources in the VLBI catalogue is a factor of two larger than the median position…
The current state of the link problem between radio and optical celestial reference frames is considered. The main objectives of the investigations in this direction during the next few years are the preparation of a comparison and the…
Between 1997 and 2004 several observing runs were conducted mainly with the CTIO 0.9 m to image ICRF counterparts (mostly QSOs) in order to determine accurate optical positions. Contemporary to these deep CCD images the same fields were…
We identify and investigate known late M, L and T dwarfs in the Gaia second data release. This sample is being used as a training set in the Gaia data processing chain of the ultra cool dwarfs work package. We find 695 objects in the…
The third Gaia Data Release (DR3) provided photometric time series of more than 2 million long-period variable (LPV) candidates. Anticipating the publication of full radial-velocity (RV) in DR4, this Focused Product Release (FPR) provides…
Streams of stars from captured dwarf galaxies and dissolved globular clusters are identifiable through the similarity of their orbital parameters, a fact that remains true long after the streams have dispersed spatially. We calculate the…
In light of substantial new discoveries of hot subdwarfs by ongoing spectroscopic surveys and the availability of the Gaia mission Early Data Release 3 (EDR3), we compiled new releases of two catalogues of hot subluminous stars: The data…
We use methods of differential astrometry to construct a small field inertial reference frame stable at the micro-arcsecond level. Such a high level of astrometric precision can be expected with the end-of-mission standard errors to be…
The nearest stars provide a fundamental constraint for our understanding of stellar physics and the Galaxy. The nearby sample serves as an anchor where all objects can be studied and understood with precise data. This work is an update of…
It is expected that the European Space Agency mission Gaia will make possible to determine coordinates in the optical domain of more than 500000 quasars. In 2006, a radio astrometry project was launched with the overall goal to make…
The link problem between radio (VLBI/ICRF) and optical (Gaia/GCRF) celestial reference frames is analyzed. Both systems should be a realization of the ICRS (International Celestial Reference System) at microarcsecond level of accuracy.…
Gaia's milli-arcsec (mas) astrometric precision allows systematic identification of optically-selected sub-kpc dual active galactic nuclei (AGN), off-nucleus AGN, and small-scale lensed quasars by `varstrometry' -- where variability-induced…
Launch of the Gaia space observatory started a new era in astrometry when the accuracy of star coordinates increased by thousands of times. Significant improvement of accuracy was also expected for the coordinates of the Solar system…
In a previous paper, we applied the Gaia DR2 catalog to improve the astrometric accuracy of about 1.7 billion objects in Pan-STARRS1 Data Release 2 (PS1 DR2). We report here on further improvements made by utilizing Gaia EDR3 and correcting…
Context. As part of Gaia Data Release 3 (Gaia DR3), epoch photometry has been released for 1.2 million sources centred on M31. This is a taster for Gaia Data Release 4 where all the epoch photometry will be released. Aims. In this paper the…