Related papers: An Updated Reference Frame for the Galactic Inner …

Masers are a unique tool to investigate the emitting gas in the innermost regions of AGNs and to map accretion disks and tori orbiting around supermassive black holes. IC485, which is classified as a LINER or Seyfert galaxy, hosts a bright…

Studying stars that are located off the Galactic plane is important for understanding the formation history of the Milky Way. We searched for SiO masers toward off-plane O-rich asymptotic giant branch (AGB) stars from the catalog presented…

Relative astrometric measurements with a precision far better than 1 mas (milli-arcsec) are commonly regarded as the domain of interferometry. Pioneering work by Pravdo & Shaklan (1996), made in the optical, reached a precision of 150…

Gaia's very accurate astrometric measurements will allow the International Celestial Reference Frame (ICRF) to be improved by a few orders of magnitude in the optical. Several sets of quasars are used to define a kinematically stable…

High resolution maps of maser emission provide very detailed information on processes occurring in circumstellar envelopes of late-type stars. A particularly detailed picture of the innermost shells around AGB stars is provided by SiO…

We establish an extragalactic, zero-motion frame of reference within the deepest optical image of a globular star cluster, an HST 123-orbit exposure of M4 (GO 8679, cycle 9). The line of sight beyond M4 (l,b (deg) = 351,16) intersects the…

Methanol masers at 6.7~GHz are well-known signposts of high-mass star-forming regions. [...] We aim to understand the origin of the ring-like structures outlined by methanol maser emission in a number of sources. This emission could be, a…

We present the first VLBI images of SiO masers in the circumstellar envelope of an S-type star obtained with the newly developed capabilities of the Very Long Baseline Array (VLBA) at 86 GHz. We combine these data with those obtained quasy…

The absolute position of the compact radio source at the dynamical center of the Galaxy, Sgr A$^*$, was known only to an accuracy of $0.2''$ in spite of its accurate location with respect to near-IR stellar sources to within 30…

We present sensitive Australia Telescope Compact Array (ATCA) observations of SiO masers in the inner parsecs of the Galactic center (GC). We detected five SiO J=2-1, v=1 (86 GHz) masers in the innner 25 arcsec (1 pc) of the GC. All the…

We measure the proper motion of the pulsar PSR J1745-2900 relative to the Galactic Center massive black hole, Sgr A*, using the Very Long Baseline Array (VLBA). The pulsar has a transverse velocity of 236 +/- 11 km s^-1 at position angle 22…

We present multi-epoch observations with the VLBA of SiO maser emission in the v=1, J=1-0 transition at 43 GHz from the remnant of the red nova V838 Mon. We model the positions of maser spots to derive a parallax of 0.166+/-0.060 mas.…

We present the galaxy stellar mass - size relation in the rest-frame near-IR ($1.5~\mu{\text{m}}$) and its evolution with redshift up to $z=2.5$. S\'ersic profiles are measured for $\sim$ $26\,000$ galaxies with stellar masses $M_\star >…

The radial distance to the co-rotation radius Rcoro (where the angular speed of the gas and stars in orbit around the Galactic Centre is equal to the angular speed of the spiral arm pattern) has often been predicted (at various places), but…

The Space Interferometry Mission (SIM), with its launch date planned for 2005, has as its goal astrometry with ~ 1 micro-arcsecond accuracy for stars as faint as 20th mag. If the SIM lives to expectations it can be used to measure…

We report H$_2$O maser line observations of the bright-rimmed globule IC 1396 N using a ground-space interferometer with the 10-m RadioAstron radio telescope as the space-based element. The source was not detected on projected baselines…

We present a new geometrical method for measuring the distance to the Galactic center (R_0) by solving for the Keplerian orbit of individual stars bound to the black hole associated with the Sgr A* from radial velocity and proper motion…

We measured the trigonometric annual parallax of H$_2$O maser source associated with the massive star-forming regions IRAS 06061+2151 with VERA. The annual parallax of $0.496\pm0.031$ mas corresponding to a distance of…

The Event Horizon Telescope (EHT), a global 230 GHz VLBI array, achieves an angular resolution of ${\approx} 20\,\mu{\rm as}$, sufficient to resolve the supermassive black hole Sagittarius A* (Sgr A*). This resolution may soon enable…

The study of the innermost circumstellar layers around AGB stars is crucial to understand how these envelopes are formed and evolve. The SiO maser emission occurs at a few stellar radii from the central star, providing direct information on…