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1.
We combined data from the Two-Micron All Sky Survey (2MASS) and USNO-A2.0 catalogues in order to derive the absolute proper motions of about 280 million stars distributed all over the sky excluding a small region near the Galactic Centre, in the magnitude range  12 < B < 19 mag  . The proper motions were derived from the 2MASS Point Sources and USNO-A2.0 catalogue positions with a mean epoch difference of about 45 years for the Northern hemisphere and about 17 years for the Southern one. The zero-point of the absolute proper motion frame (the 'absolute calibration') was specified with the use of about 1.45 million galaxies from 2MASS. Most of the systematic zonal errors inherent in the USNO-A2.0 catalogue were eliminated before the calculation of proper motions. The mean formal error of absolute calibration is less than 1 mas yr−1. The XPM Catalogue will be available via CDS in Strasbourg during 2010. The generated catalogue contains the International Celestial Reference System positions of stars for the J2000 epoch, original absolute proper motions, as well as   B , R , J , H   and K magnitudes. A comparison of the proper motions obtained in this work with the data of other recent catalogues of quasars was fulfilled.  相似文献   

2.
The UK Infrared Telescope Infrared Deep Sky Survey (UKIDSS) is the first of a new generation of infrared surveys. Here, we combine the data from two UKIDSS components, the Large Area Survey (LAS) and the Galactic Cluster Survey (GCS), with Two-Micron All-Sky Survey (2MASS) data to produce an infrared proper motion survey for low-mass stars and brown dwarfs. In total, we detect 267 low-mass stars and brown dwarfs with significant proper motions. We recover all 10 known single L dwarfs and the one known T dwarf above the 2MASS detection limit in our LAS survey area and identify eight additional new candidate L dwarfs. We also find one new candidate L dwarf in our GCS sample. Our sample also contains objects from 11 potential common proper motion binaries. Finally, we test our proper motions and find that while the LAS objects have proper motions consistent with absolute proper motions, the GCS stars may have proper motions which are significantly underestimated. This is possibly due to the bulk motion of some of the local astrometric reference stars used in the proper motion determination.  相似文献   

3.
A proper motion study from Tautenburg Schmidt plates is presented for the globular cluster M3 and its vicinity. The plates were scanned with the Automated Photographic Measuring (APM) system in Cambridge (UK). A photographic B,V photometry and star counts on the deepest plates were carried out. With a limiting magnitude of about B = 21.4 proper motions with an accuracy from 2 to 3 mas/yr have been obtained for stars with B 19. The proper motions were determined using a stepwise regression method with 3rd order polynomials in the plate-to-plate solutions with about 2000 reference galaxies. The results which were corrected for systematic errors dependent on position and magnitude of the stars were used for the determination of membership probabilities. We also looked for possible internal motions of M3.  相似文献   

4.
Astrometric CCD observations of 1123 stars with large proper motions (μ > 300 mas yr−1) from the LSPM (I/298) catalog in the declination zone +30°–+70° have been carried out with the Pulkovo normal astrograph since 2006. The observational program includes mostly stars that previously have not entered into high-accuracy projects to determine the proper motions. Our studies are aimed at determining new proper motions of fast stars in the HCRF/UCAC3 system and searching for stars with invisible companions in the immediate Galactic neighborhoods of the Sun. Having analyzed about 10 000 CCD frames, we have obtained the equatorial coordinates of 414 program stars in the HCRF/UCAC3 system at an accuracy level of 10–50 mas and determined their new proper motions. To derive the proper motions, we have used the data from several star catalogs and surveys (M2000, CMC14, 2MASS, SDSS) as early epochs. The epoch differences range from 5 to 13 years (on average, about 10 years); the mean accuracy of the derived proper motions is 4–5 mas yr−1. For 70 stars, we have revealed significant differences between the derived proper motions and those from the LSPM and I/306A catalogs (these proper motions characterize the mean motion of the photocenter in 50 years or more). Apart from systematic errors, these differences can result from the existence of invisible components of the program stars.  相似文献   

5.
36 objects with mainly negative (U—B) indices were investigated for variability and proper motions. 10 objects with significant or suspected proper motions and 8 variable objects were detected. Using these criteria, it was possible to separate white dwarfs from quasi-stellar objects to some extent.  相似文献   

6.
We measured relative proper motions with a typical accuracy of 1.0 milliarcsec/year (mas/a) for 2000 stars in a 1°4 × 1°4 field around the low-latitude globular cluster NGC 6934. Four plates taken with the Bonn double refractor, spanning an epoch difference of 62 years, were digitized completely. Within the tidal radius of the cluster, we find 106 stars with proper motion errors less than 5 mas/a. Membership probalilities are computed taking into account the individual proper motion errors and the radial distances to the cluster centre. We derive the mean relative proper motion of NGC 6934 using stars with high membership probabilities from radial velocities (Smith and Bell 1986) or from their location in the colour-magnitude diagram (Harris and Racine 1973). The relative proper motions of four Hipparcos stars in the field will be used to obtain the absolute proper motion of NGC 6934 once the extragalactically calibrated Hipparcos Output Catalogue is available.  相似文献   

7.
球状星团是银河系中最年老的天体之一，是储存着银河系早期演化珍贵信息的“化石”．球状星团的天体测量，主要包括球状星因天区内恒星相对自行的测定，并由这些相对自行数据采用适当方法定出星团的绝对自行，或者直接测定绝对自行．利用这些自行数据，或者进一步与测光和视向速度数据结合，可以开展与球状星团的距离、运动、动力学状况、质量、年龄、演化等等以及银河系的结构和演化等有关的一系列重要的研究．在本文中对本世纪70年代中期以来在球状星团相对自行测定和成员概率估计、内部运动检测、绝对自行测定和空间运动研究这三方面取得的成果和进展以及存在的问题作了评述．  相似文献   

8.
The Commission 19 (Earth Rotation) of the International Astronomical Union—IAU established the Working Group on Earth Rotation in the Hipparcos Reference Frame—WG ERHRF at 1995 to collect the optical observations of latitude and universal time variations, made during 1899.7-1992.0 in line with Earth orientation programmes (to derive Earth Orientation Parameters—EOP), with Dr. Jan Vondrák (Astronomical Institute of Academy of Sciences of the Czech Republic, Prague) as the head of WG ERHRF. Dr. Vondrák collected about 4.4 million optical observations of latitude/universal time variations made at 33 observatories. These data were used for EOP investigations, Hipparcos Catalogue—radio sources connection, etc. Nowadays, it is used to correct the positions and proper motions of stars of Hipparcos Catalogue (as an optical reference frame) using ground-based observations of some Hipparcos stars. After Hipparcos Catalogue, some new astrometric catalogues appeared (as ARIHIP, EOC-2, etc.) with better accuracy of proper motions. We use the latitude observations made by visual zenith-telescope (ZT), as classical astrometric instrument, at seven observatories (all over the world) of International Latitude Service—ILS. The observations were used in the programmes of monitoring the Earth orientation during the 20th century. We received the data from Dr. Vondrák via private communication. The observatories are Carloforte—CA, Cincinnati—CI, Gaithersburg—GT, Kitab—KZ, Mizusawa—MZZ, Tschardjui—TS and Ukiah—UK. The task is to improve proper motions in declination of the observed Hipparcos stars. The original method was developed. We removed from the instantaneous observed latitudes, all known effects (polar motion and some local instrumental errors), and the corrected latitudes were then the input data to calculate the corrections of Hipparcos proper motions in declination using the least squares method—LSM with the linear model. We did an improvement of Hipparcos proper motions in declination via mentioned latitude variations with time by using a long-term (a few decades) visual zenith-telescope data of ILS. The calculated results were compared with the ARIHIP and EOC-2 data, and the consistency were good. The main steps of the calculations and some of the results are presented here.  相似文献   

9.
The expected error of the connection of the HIPPARCOS system with an extragalactic reference system by means of ground-based photographic astrometry was calculated. Two different catalogues of proper motions with respect to extragalactic objects and the HIPPARCOS proper motions were simulated. An accuracy of 0″14 per century using only 10 fields with 119 link stars of the Tautenburg Schmidt telescope (134/200/400) and 0″07 per century using 93 fields with 336 link stars of the Kiev long focus astrograph (40/550) were obtained.  相似文献   

10.
In a program conducted to isolate AGK3 stars with large proper motions, it has been found that more than one hundred stars seem to be affected by large errors in their published proper motions. For some of those objects south of +25 degrees, new proper motions are being obtained using, as first-epoch positions, the published material of the Astrographic Catalogue. Second-epoch positions are derived from new plates taken with the Yale Southern Observatory double astrograph.  相似文献   

11.
We cross-match objects from several different astronomical catalogs to determine the absolute proper motions of stars within the 30-arcmin radius fields of 115 Milky-Way globular clusters with the accuracy of 1–2 mas yr?1. The proper motions are based on positional data recovered from the USNO-B1, 2MASS, URAT1, ALLWISE, UCAC5, and Gaia DR1 surveys with up to ten positions spanning an epoch difference of up to about 65 years, and reduced to Gaia DR1 TGAS frame using UCAC5 as the reference catalog. Cluster members are photometrically identified by selecting horizontal- and red-giant branch stars on color–magnitude diagrams, and the mean absolute proper motions of the clusters with a typical formal error of about 0.4 mas yr?1 are computed by averaging the proper motions of selected members. The inferred absolute proper motions of clusters are combined with available radial-velocity data and heliocentric distance estimates to compute the cluster orbits in terms of the Galactic potential models based on Miyamoto and Nagai disk, Hernquist spheroid, and modified isothermal dark-matter halo (axisymmetric model without a bar) and the same model + rotating Ferre’s bar (non-axisymmetric). Five distant clusters have higher-than-escape velocities, most likely due to large errors of computed transversal velocities, whereas the computed orbits of all other clusters remain bound to the Galaxy. Unlike previously published results, we find the bar to affect substantially the orbits of most of the clusters, even those at large Galactocentric distances, bringing appreciable chaotization, especially in the portions of the orbits close to the Galactic center, and stretching out the orbits of some of the thick-disk clusters.  相似文献   

12.
After publication of the Hipparcos catalogue (in 1997), a few new astrometric catalogues have appeared (TYCHO‐2, ARIHIP, etc.), as a good combination of the Hipparcos satellite and ground‐based data, to get more accurate coordinates and proper motions of stars than the Hipparcos catalogue ones. There are also investigations on improving the Hipparcos coordinates and proper motions by using the astrometric observations of latitude and universal time variations (via observed stars referred to Hipparcos catalogue), together with Hipparcos data, carried out during the last few years. These kind of ground‐based data were collected at the end of the last century by J. Vondrák. There are about 4.4 million optical observations made worldwide at 33 observatories and with 47 instruments during 1899.7–1992.0; our Belgrade visual zenith telescope data (for the period 1949.0‐1986.0) were included. First of all, these data were used to determine the Earth Orientation Parameters – EOP, but they are also useful for the opposite task – to check the accuracy of coordinates and proper motions of Hipparcos stars which were observed from the ground over many decades. Here, we use the latitude part of ten Photographic Zenith Tubes – PZT data (more than 0.9 million observations made at 6 observatories during the time interval 1915.8–1992.0), and combine them with the Hipparcos catalogue ones, with suitable weights, in order to check the proper motions in declination for 807 common PZT/Hipparcos stars (and to construct the PZT catalogue of μδ for 807 stars). Our standard errors in proper motions in declination of these stars are less than or equal to the Hipparcos ones for 423 stars. The mean value of standard errors of 313 stars observed over more than 20 years by PZT is 0.40 mas/yr. This is 53% of 0.75 mas/yr (the suitable value from the Hipparcos catalogue). We used the Least Squares Method – LSM with the linear model. Our results are in good agreement with the Earth Orientation Catalogue – EOC‐2 and the new Hipparcos ones. The main steps of the method and the investigations of systematic errors in determined proper motions (the proper motion differences with respect to the Hipparcos values, the EOC‐2 ones and the new Hipparcos ones, as a function of α, δ, and magnitude) are presented here. A comparison of the four catalogues by pairs shows that there is no significant relationship between the differences of their μδ values and magnitudes and color indices of the common 807 stars. All catalogues have relatively small random and systematic errors which are close to each other. However, the comparison shows that our formal errors are too small. They are underestimated by a factor of nearly 1.7 (for EOC‐2, it is 2.0) if we take the new Hipparcos (or Hipparcos) data as reference (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

13.
利用上海天文台的照相底片资料,确定了疏散星团NGC6530天区364颗恒星的自行和成员概率,并对有关自行测定的方法、结果和精度等问题作了较为详细的介绍和讨论。使用的底片历元差为87年,全部恒星自行中误差的均方根值为1．09mas/a。  相似文献   

14.
Comparing absolute proper motions of stars obtained by different methods from observations with the Tautenburg Schmidt telescope (134/200/400), the Kiev long focus astrograph (40/550) and the Pulkovo normal astrograph (33/350) the external accuracy of the Tautenburg absolute proper motions was examined. It agrees well with the Tautenburg internal accuracy which is known from earlier investigations as 0″.7 per century. That accuracy was now achieved for all AGK3 stars in the M33 field including the bright stars from 7m to 10m.  相似文献   

15.
Astrometric CCD observations of stars with large proper motions were carried out during 2008–2014 using telescopes of the Nikolaev Astronomical Observatory. A catalog of positions and proper motion of 1596 fast stars with proper motions exceeding 150 mas/yr has been compiled based on observation results. The catalog covers the declination zone from 0° to 65°. The standard error of derived proper motion is 1…10 mas/yr for both coordinates depending on the observational history of the star. Data from eight different star catalogs and surveys have been used to derive proper motion. The comparison results of proper motion with data from modern catalogs and results of the statistical test for the detection of possible invisible components are given.  相似文献   

16.
Cr 135 revisited     
In this paper we combine information on photometry, radial velocities and proper motions to study the nature of the suspected open cluster Cr 135. For the first time we introduce proper motions of a large number of stars in the region of Cr 135 into the discussion. The proper motions taken from the PPM catalogue favour the hypothesis that Cr 135 is a real open cluster with at least 12 members at a distance of 300 pc having a space motion U, V, W of (−11, −13, −15) km s−1. But still more accurate observations are needed to separate it from the field stars without any doubt.  相似文献   

17.
Radio tracking of the Sun over 6 hrs around transit was made by the Miyun 460 MHz compound interferometer to determine the two-imensional positions of Type-I sources and their proper motions. The measuring error in relative position was less than 0.1'.

Most of Type-I sources show slow motions at times. The speed ranges from the interferometer threshold of 0.2′/hr to 2′/hr (2.4(+6) cm/s). The largest proper motion found was 5' in 6 hrs, but the usual amplitudes were 1'-2' in 6 hrs. Active regions with moving Type-I sources show more flare activity, i.e. more flares of importance class 1 or greater within a three day period around the day when the source shows motion, while other regions are not so active. The proper motion is sometimes related to photospheric phenomena.

We believe that the proper motion of a Type-I source is a reflection of the changing configuration of the coronal magnetic field above the active region and this variation could be related to flare activity.  相似文献   


18.
Summary In this paper the results of the research of the stars proper motions Trapezium components are reported. They are: the galactic coordinates of the solar aprx and the Sun velocity (L ⊙=43±18°,B ⊙=+28±13°,V ⊙=13±4 km s−1), the dispersion of peculiar velocities in the direction of the galactic coordinates for the above mentioned stars (σ l =±11 km s−1, σ b =±7 km s−1).The attained accuracy of the proper motions (±0.005″ yr−1) is shown to be insufficient to the study of internal space motions in these systems. At present the work to increase the relative proper motions accuracy for multiple system components and to improve reductions from the relative to absolute proper motions, is being carried out in the Main Astronomical Observatory (Academy of Sciences of the Ukrainian SSR). The new catalogue of the AGK3 stars is composed now in the vicinity of the galactic equator in order to improve reductions from the relative to absolute proper motions. The r.m.s. errors of the proper motions, obtained in the AGK3 system, are ±0.005″ yr−1.  相似文献   

19.
Based on a sample of RR Lyrae variable stars including more than 9000 objects with proper motions and distances, we have investigated the kinematics of the Galactic halo from the two-dimensional velocity field. We have used both the proper motions deduced independently by us from the positional data taken from all-sky catalogues in a time interval up to 65 years and the proper motions taken from the Gaia DR2 catalogue. In addition, we have also studied the halo kinematics from the three-dimensional velocity field of ~850 RR Lyrae variables with distances, proper motions, and line-of-sight velocities. The kinematic parameters describing the velocity field have been estimated by the maximum-likelihood method; their change with Galactocentric distance has been investigated. The radial velocity dispersion in spherical coordinates σr ≈ 160?170 km s?1 exceeds its values from previous papers approximately by 20 km s?1, while the anisotropy parameter β ≈ 0.68?0.72 agrees satisfactorily with previous studies. When estimating the rotation velocity of the population of RR Lyrae stars, we identified the inner and outer halos with weak prograde and retrograde rotations, respectively.  相似文献   

20.
There is currently a clear discrepancy in the proper motions measured on different angular scales in the approaching radio jets of the black hole X-ray binary GRS 1915+105. Lower velocities were measured with the Very Large Array (VLA) prior to 1996 than were subsequently found from higher resolution observations made with the Very Long Baseline Array and the Multi-Element Radio Linked Interferometer Network. We initiated an observing campaign to use all three arrays to attempt to track the motion of the jet knots from the 2006 February outburst of the source, giving us unprecedented simultaneous coverage of all angular scales, from milliarcsecond scales out to arcsecond scales. The derived proper motion, which was dominated by the VLA measurements, was found to be 17.0 mas d−1, demonstrating that there has been no significant permanent change in the properties of the jets since 1994. We find no conclusive evidence for deceleration of the jet knots, unless this occurs within 70 mas of the core. We discuss possible causes for the varying proper motions recorded in the literature.  相似文献   

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