We present infrared K-band photometry of complete samples of VLM candidates constructed from IIIaF and IVN plates in 10 fields taken as part of the POSSII and UKSRC surveys. Using the I-K colors constructed for these stars we estimate a bolometric luminosity function which extends to MBol=13.75. We find significant evidence for a luminosity function decreasing toward these luminosities.
We propose new estimates of the secular aberration drift, mainly due to the rotation of the Solar System about the Galactic center, based on up-to-date VLBI observations and and improved method of outlier elimination. We fit degree-2 vector spherical harmonics to extragalactic radio source proper motion field derived from geodetic VLBI observations spanning 1979-2013. We pay particular attention to the outlier elimination procedure to remove outliers from (i) radio source coordinate time series and (ii) the proper motion sample. We obtain more accurate values of the Solar system acceleration compared to those in our previous paper. The acceleration vector is oriented towards the Galactic center within ~7{deg}. The component perpendicular to the Galactic plane is statistically insignificant. We show that an insufficient cleaning of the data set can lead to strong variations in the dipole amplitude and orientation, and statistically biased results.
The FK4 was an attempt to establish a fundamental system of stellar positions and proper motions for the 1950 equinox using as much position data as were available. Most of the stars are brighter than 7.0 mag. To increase the star density in some regions of the sky, positions and proper motions for additional stars were established on the same system. This catalog contains seven data files, six for different equinoxes (1950, 1955, 1960, 1965, 1970, and 1975) and one for the supplemental stars. The 1950 and 1975 files contain the complete FK4 catalog (1535 stars); the others contain only 52 polar stars. In addition to a header record, the primary catalog contains for each star an identification number; the magnitude (maximum for a variable star); a variability flag, the minimum magnitude for a variable or the magnitude of the secondary for a double star; the HD spectral type and the type for the companion or a second type for a variable star; the position and the change and acceleration of the position; the proper motion and its change with time; the mean epoch of the observations for both right ascension and declination; the standard deviations of the position and proper motion; the numbers of the star in the Boss General Catalog, the N30 catalog, and in the Durchmusterungs; and the parallax. The supplement has a flag to indicate duplicity but no information about variability or the second component. It has no information about the temporal change of the position and proper motion and does not list the N30 and Durchmusterung numbers. It also omits the mean epoch for the observations.
On the photon counter data observed with Photoeleetric Transit Instrument of Beijing Astronomical Observatory during the period from 1988 to 1990, corrections of right ascensions of 324 stars are given. The mean precision (<m_{DELTA}{alpha}cos{delta}_>) is 4.7ms. The mean observational epoch is 1989.7. The relations of residuals with magnitudes and spectral types are discussed and given respectively. Finally the systematic corrections (PPCP4-FK4) are also analysed.
Using the data observed with the Photoelectric Astrolabe Mark II of the Beijing Astronomical Observatory (PPA) during the period from 1982 to 1990, the Fourth Preliminary Catalogue of Stars (PACP4) have been Compiled. It consists of 1969 stars including 650 FK5 stars and 1319 GC stars. The mean precisions of position corrections in right ascension and declination are 4.1 ms and 0.067", respectively. The declinations are from +11 deg to +69 deg. The magnitudes are from 0.1 to 7.3. The mean epoch of observations is 1986.8.
Here, we present a catalogue of known Fast Radio Burst sources in the form of an online catalogue, FRBCAT. The catalogue includes information about the instrumentation used for the observations for each detected burst, the measured quantities from each observation, and model-dependent quantities derived from observed quantities. To aid in consistent comparisons of burst properties such as width and signal-to-noise ratios, we have re-processed all the bursts for which we have access to the raw data, with software which we make available. The originally derived properties are also listed for comparison.
We improve the widely used friends-of-friends (FoF) group finding algorithm with membership refinement procedures and apply the method to a combined dataset of galaxies in the local Universe. A major aim of the refinement is to detect subgroups within the FoF groups, enabling a more reliable suppression of the fingers-of-God effect. The FoF algorithm is often suspected of leaving subsystems of groups and clusters undetected. We used a galaxy sample built of the 2MRS, CF2, and 2M++ survey data comprising nearly 80000 galaxies within the local volume of 430Mpc radius to detect FoF groups. We conducted a multimodality check on the detected groups in search for subgroups. We furthermore refined group membership using the group virial radius and escape velocity to expose unbound galaxies. We used the virial theorem to estimate group masses. The analysis results in a catalogue of 6282 galaxy groups in the 2MRS sample with two or more members, together with their mass estimates. About half of the initial FoF groups with ten or more members were split into smaller systems with the multimodality check.
The paper presents the results of determination of fundamental parameters (effective temperature, surface gravity, luminosity, mass, radius, rotation velocity, and radial velocity) for 146 stars observed at the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences with the Main Stellar Spectrograph during 2009-2011; 124 of the stars are magnetic or potentially magnetic objects. We obtained and analyzed at least 500 pairs of circularly-polarized-emission spectra. Various methods and approaches were used in estimating the fundamental parameters.
In this era of large spectroscopic surveys of stars of the Milky Way, pipelines need to be tested and validated against a set of well-known stars. The Gaia FGK benchmark stars (GBS) are among the preferred samples of reference stars. They consist of a small but carefully selected sample of stars whose parameters are derived consistently and homogeneously. A series of papers has been published that discuss the definition and evolution of the sample of GBS. Here we summarise this work and provide our current list of stars with associated parameters which are recommended for validation and calibration purposes for stellar surveys.
The definition, construction and realization of a reference system is one of the oldest and most fundamental tasks of astronomy. Currently, the ICRS (International Celestial Reference System), realized by the ICRF (International Celestial Reference Frame) or ICRF2, is the reference system adopted by the IAU. It is based on the very precise VLBI positions of a few hundred compact extragalactic radio sources. Despite its excellent precision, the ICRF is far from providing a reference system that is available for the entire sky and accessible to all observers. The ICRF has to be densified and extended to other wavelengths, mainly to the optical domain where the astronomical activities are more intense. For this reason, the IAU has recommended and encouraged works in this direction over the years. Many of them were developed to give sometimes good positions and proper motions, but they are very limited in magnitude, while others are extremely dense and deep in magnitude but have low accuracy, mainly for the proper motions. Nevertheless, all these contributions are very important because they are complementary. We present a homogeneous and precise optical astrometric catalog that extends the ICRF in the direction of 12 low-extinction windows of the Galactic bulge and provides at the same time a useful database for kinematic studies.
