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Register a new userA New All-Sky Catalog of Stars with Large Proper Motions
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A new all-sky catalog of stars with proper motions pm>0.15/yr is presented. The catalog is largely a product of the SUPERBLINK survey, a data-mining initiative in which the entire Digitized Sky Surveys are searched for moving stellar sources. Findings from earlier proper motions surveys are also incorporated. The new all-sky catalog supersedes the great historic proper motion catalogs assembled by W. J. Luyten (LHS, NLTT), and provides a virtually complete (>98%) census of high proper motion stars down to magnitude R=19.
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Based on observations performed with the Pulkovo normal astrograph in 2008-2015 and data from sky surveys (DSS, 2MASS, SDSS DR12, WISE), we have investigated the motions of 1308 stars with proper motions larger than 300 mas/yr down to magnitude 17. The main idea of our search for binary stars based on this material is reduced to comparing the quasi-mean (POSS2-POSS1; an epoch difference of $approx$50 yr) and quasi-instantaneous (2MASS, SDSS, WISE, Pulkovo; an epoch difference of $approx$10 yr) proper motions. If the difference is statistically significant compared to the proper motion errors, then the object may be considered as a {Delta}{mu}-binary candidate. One hundred and twenty one stars from among those included in the observational program satisfy this requirement. Additional confirmations of binarity for a number of stars have been obtained by comparing the calculated proper motions with the data from several programs of stellar trigonometric parallax determinations and by analyzing the asymmetry of stellar images on sky-survey CCD frames. Analysis of the highly accurate SDSS photometric data for four stars (J0656+3827, J0838+3940, J1229+5332, J2330+4639) allows us to reach a conclusion about the probability that these {Delta}{mu} binaries are white dwarf + M dwarf pairs.
The infrared source known as Orion n was detected in 1980 with observations made with the 3.8-m United Kingdom Infrared Telescope. About two decades later, sensitive observations made with the Very Large Array revealed the presence of a mJy double radio source apparently coincident in position with the infrared source n. The radio source was assumed to be the counterpart of the infrared source. However, over the years it has been concluded that the radio source shows large proper motions to the south while the infrared source n is stationary. Here we reanalyze the proper motions of the radio source adding both older and newer VLA observations than previously used. We confirm the proper motions of the radio source that at present no longer coincides positionally with the infrared source. The solution to this problem is, most probably, that the infrared source n and the radio source are not the same object: the infrared source is a stationary object in the region while the radio counterpart is moving as a result of the explosion that took place in this region some 500 years ago and that expelled large amounts of molecular gas as well as several compact sources. Considering the paper where it was first reported, we refer to this double radio source as Orion MR. In addition, we use these new observations to fully confirm the large proper motions of the sources IRc23 and Zapata 11. Together with sources BN, I, Orion MR, and x, there are at least six compact sources that recede from a point in common in Orion BN/KL. However, IRc23 is peculiar in that its ejection age appears to be only $sim$300 years. The relatively large number of sources rules out as a possible mechanism the classic three-body scenario since then only two escaping bodies are expected: a tight binary plus the third star involved in the encounter.
We collected radial velocities of more than 50.000 individual stars in 156 Galactic globular clusters (GGC) and matched them with HST photometry and Gaia DR2 proper motions. This allowed us to derive the GGCs mean proper motions and space velocities. By fitting a large set of N-body simulations to their velocity dispersion and surface density profiles, combined with new measurements of their internal radially dependent mass functions, we have determined their present-day masses and structural parameters, and for 144 GGCs their internal kinematics. We also derive the initial cluster masses by calculating the cluster orbits backwards in time applying suitable recipes to account for mass-loss and dynamical friction. The new fundamental parameters of GGCs are publicly available via an online database, which will regularly be updated.
New astrometric reductions of the US Naval Observatory CCD Astrograph Catalog (UCAC) all-sky observations were performed from first principles using the TGAS stars in the 8 to 11 magnitude range as reference star catalog. Significant improvements in the astrometric solutions were obtained and the UCAC5 catalog of mean positions at a mean epoch near 2001 was generated. By combining UCAC5 with Gaia DR1 data new proper motions on the Gaia coordinate system for over 107 million stars were obtained with typical accuracies of 1 to 2 mas/yr (R = 11 to 15 mag), and about 5 mas/yr at 16th mag. Proper motions of most TGAS stars are improved over their Gaia data and the precision level of TGAS proper motions is extended to many millions more, fainter stars. External comparisons were made using stellar cluster fields and extragalactic sources. The TGAS data allow us to derive the limiting precision of the UCAC x,y data, which is significantly better than 1/100 pixel.
The Asteroid Terrestrial-impact Last Alert System (ATLAS) observes most of the sky every night in search of dangerous asteroids. Its data are also used to search for photometric variability, where sensitivity to variability is limited by photometric accuracy. Since each exposure spans 7.6 deg corner to corner, variations in atmospheric transparency in excess of 0.01 mag are common, and 0.01 mag photometry cannot be achieved by using a constant flat field calibration image. We therefore have assembled an all-sky reference catalog of approximately one billion stars to m~19 from a variety of sources to calibrate each exposures astrometry and photometry. Gaia DR2 is the source of astrometry for this ATLAS Refcat2. The sources of g, r, i, z photometry include Pan-STARRS DR1, the ATLAS Pathfinder photometry project, ATLAS re-flattened APASS data, SkyMapper DR1, APASS DR9, the Tycho-2 catalog, and the Yale Bright Star Catalog. We have attempted to make this catalog at least 99% complete to m<19, including the brightest stars in the sky. We believe that the systematic errors are no larger than 5 millimag RMS, although errors are as large as 20 millimag in small patches near the galactic plane.
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