We analyze data from the Hubble Space Telescope's (HST) Advanced Camera for Surveys of the globular cluster (GC) Omega Cen. We construct a photometric catalog of 1.2x10^6^ stars over a 10'x10' central field down to below B_F435W_=25 (M~0.35M_{sun}_). The 2.5 to 4 year baseline between observations yields a catalog of some 10^5^ proper motions over a smaller area, with 53382 "high-quality" measurements in a central R<~2' field. Artificial-star tests characterize the photometric incompleteness. We determine the cluster center to ~1" accuracy from star counts using two different methods, one based on isodensity contours and the other on "pie slices." We independently confirm the result by determining also the kinematical center of the HST proper motions, as well as the center of unresolved light seen in Two Micron All Sky Survey data. All results agree to within their 1"-2" levels of uncertainty. The proper-motion dispersion of the cluster increases gradually inward, but there is no variation in kinematics with position within the central ~15": there is no dispersion cusp and no stars with unusually high velocities. We measure for the first time in any GC the variation in internal kinematics along the main sequence.
The tables present the photometric and astrometric results of an extensive proper motion study of the globular cluster omega Centauri: information on the photographic plates used, variability analysis, astrometric data for 9847 stars, membership determination and surface density profile, cluster proper motion dispersions and systematics and cross-references with star-numbers used by Norris et al. (1997ApJ...487L.187N) and Lynga (1996A&AS..115..297L).
The plates of wide-field astrograph are used to measure the proper motions of 1065 stars in 1.8x1.8 deg. field of the open cluster NGC 7063. The magnitude equation is analysed, and the cluster members are identified.
A proper-motion study of a field of 20'x20' inside Plaut's low-extinction window (l,b) = (0{deg}, -8{deg}) has been completed. Relative proper motions and photographic BV photometry have been derived for ~21000 stars reaching to V~20.5mag, based on the astrometric reduction of 43 photographic plates, spanning over 21yr of epoch difference. Proper-motion errors are typically 1mas/yr, and field-dependent systematics are below 0.2mas/yr. Cross-referencing with the 2MASS catalog yielded a sample of ~8700 stars, from which predominantly disk and bulge subsamples were selected photometrically from the JH color-magnitude diagram. The two samples exhibited different proper-motion distributions, with the disk displaying the expected reflex solar motion as a function of magnitude.
High-precision proper motions for 257 and 296 stars in a 90'x90' region centered on BD+20 2170 were obtained from seven plates taken with the Zo-se 40cm refractor (f=6895mm) in March, 1986 (see the "Plate Summary" section below), combined with six AC plates and the stellar positions in Russell's (1976, Ph.D. Thesis, Pittsburgh University). Combined with other data, membership probabilities were estimated by an improved maximum likelihood method. A very good sample of 198 members is obtained with proper motion accuracies ranging from +/-0.2 to +/-5.0mas/yr, of which 60% are better than +/-1.0mas/yr; the completeness limit is about B=15.5mag. Note that the table published in electronic form associated to the paper published in 1995A&AS..113..419W presented positions not correctly associated to the stars (see the "History" section below)
We have used COSMOS scans of photographic plates taken by the Palomar Oschin Schmidt telescope (as part of the original Palomar Sky Survey) and by the UK Schmidt telescope to obtain proper motions for ~ 450 000 stars within a 112-degree region covering part of the Hyades cluster. With epoch differences of 33 to 37 yr, we have obtained proper motions accurate to 6-12 mas/yr and have identified 393 candidate Hyads to a limiting magnitude of Mv ~ +15.5, including at least two new white dwarf candidates. The main-sequence luminosity function determined from our sample is similar to that defined by local field stars, with a broad maximum at Mv ~ +12. Deriving distances from mu u, the proper motion towards the convergent point, and the space velocity determined by Gunn et al., we find stars with motions consistent with membership at distances of more than 15pc from the cluster centre. Moreover, both the line-of-sight and surface density distributions show evidence for significant mass segregation - indeed, the overall proper motion distribution suggests a tight core centred within a much broader distribution. We derive a total mass of 410-480Sun and a gravitational binding radius of ~ 10.5pc.
The proper motions were derived from comparison catalogues AGK3R, KSZ. This catalogues was observed with Repsold meridian circle at Nikolaev observatory during the years 1956-65; AGK2, Yale (1928-1933) and AGK1 (1968-1905). The mean errors (M.E.) of annual proper motions are M.E.(in Mu-Alfa x cos Decl.) = +/- 0.0002-0.0003 timesec/year M.E.(in Mu-Decl.) = +/- 0.003-0.005 arcsec/year Proper motions were obtained in the FK3 system. The usage of the AGK1 catalogue allowed the author to increase the epoch differences up to 90 years and to obtain the maximum precision at the present time.
We present a proper motion mini-survey of 35 fields in the vicinity of Baade window, (l, b) = (1{deg}, 4{deg}), sampling roughly a 5x2.5deg^2^ region of the Galactic bar. Our second epoch observations collected with the Advanced Camera for Surveys/High Resolution Channel instrument onboard the Hubble Space Telescope were combined with the archival Wide Field Planetary Camera 2/PC images. The resulting time baselines are in the range of 4 to 8yr. Precise proper motions of 15863 stars were determined in the reference frame defined by the mean motion of stars with magnitudes between I_F814W_=16.5 and 21.5 along the line of sight.
We present new blue straggler star (BSS) catalogues in 38 Milky Way globular clusters (GCs) based on multipassband and multi-epoch treasury survey data from the Hubble Space Telescope. We measure precise astrometry and relative proper motions of stars in all target clusters and performed a subsequent cluster membership selection. We study the accuracy of our proper-motion measurements using estimates of central velocity dispersions and find very good agreement with previous studies in the literature. Finally, we present a homogeneous BSS selection method, that expands the classic BSS selection parameter space to more evolved BSS evolutionary stages. We apply this method to the proper-motion cleaned GC star catalogues in order to define proper-motion cleaned BSS catalogues in all 38 GCs, which we make publicly available to enable further study and follow-up observations.
