scholarly journals CPC2 Reduction with Hipparcos and Proper Motions in The Southern Hemisphere

1998 ◽  
Vol 11 (1) ◽  
pp. 551-551
Author(s):  
N. Zacharias ◽  
M.I. Zacharias ◽  
C. de Vegt ◽  
C.A. Murray
Keyword(s):  
Southern Hemisphere ◽  
Systematic Errors ◽  
Reference Star ◽  
Proper Motions ◽  
Positional Accuracy ◽  
Star Catalog ◽  
Naval Observatory ◽  
Celestial Reference System ◽  
First Time ◽  
Better Than

The Second Cape Photographic Catalog (CPC2) contains 276,131 stars covering the entire Southern Hemisphere in a 4-fold overlap pattern. Its mean epoch is 1968, which makes it a key catalog for proper motions. A new reduction of the 5687 plates using on average 40 Hipparcos stars per plate has resulted in a vastly improved catalog with a positional accuracy of about 40 mas (median value) per coordinate, which comes very close to the measuring precision. In particular, for the first time systematic errors depending on magnitude and color can be solved unambiguously and have been removed from the catalog. In combination with the Tycho Catalogue (mean epoch 1991.25) and the upcoming U.S. Naval Observatory CCD Astrograph Catalog (UCAC) project proper motions better than 2 mas/yr can be obtained. This will lead to a vastly improved reference star catalog in the Southern Hemisphere for the final Astrographic Catalogue (AC) reductions, which will then provide propermotions for millions of stars when combined with new epoch data. These data then will allow an uncompromised reduction of the southern Schmidt surveys on the International Celestial Reference System (ICRS).

scholarly journals Systematic Differences Instrument Minus FK5 in the Southern Hemisphere

1990 ◽  
Vol 141 ◽  
pp. 385-386
Author(s):  
G. Carrasco ◽  
P. Loyola
Keyword(s):  
Southern Hemisphere ◽  
Astronomical Observatory ◽  
Reference Star ◽  
Meridian Circle ◽  
Proper Motions ◽  
Faint Star ◽  
International Reference ◽  
Star Catalogue

Observations of Fundamental Faint Star Catalogue (FKSZ) stars, made with the Repsold Meridian Circle at Cerro Calán National Astronomical Observatory, began in 1979 and finished in 1988. Today International Reference Star (IRS) observations are in progress. These observations correspond to the second epoch of the Santiago 67 Catalogue (Carrasco and Loyola 1981) and they are going to be used for determining the proper motions of these stars.

scholarly journals On the Project of a New Fourfold Coverage of the Northern Hemisphere

1974 ◽  
Vol 61 ◽  
pp. 209-215
Author(s):  
Chr. de Vegt
Keyword(s):  
Northern Hemisphere ◽  
Spectral Region ◽  
Reference Star ◽  
Star System ◽  
Proper Motions ◽  
Plate Material ◽  
Positional Accuracy ◽  
Technical Description ◽  
Suitable Reference

The fully inherent information of the AGK 2 plate material, covering the northern hemisphere down to δ= −2.5° with homogeneous epoch and limiting magnitude has not been used to establish the AGK2 catalogue. A new measurement will provide positions for all stars with at least mpg=2 in the FK4 system, yielding an estimated accuracy of σ = 0″.14.In March 1973 a newly developed zone astrograph for the yellow spectral-region has been set in operation at the Hamburg observatory which would be available about 1975 for a new fourfold coverage of the northern hemisphere. A technical description of the instrument is given. Details of the fourfold plate coverage and the observing program are discussed. As a suitable reference star system the AGK3R catalogue, updated with recently derived proper motions to that epoch, is adopted. A final positional accuracy σ = 0″.11 of the new catalogue is expected. The available epoch difference of 45 years up to that date will then provide proper motions in the FK 4 system with an estimated accuracy of at least 0″.005/a for all stars of the northern hemisphere down to mpg=2.

scholarly journals Improvement of the Optical Reference System by Photographic Astrometry: First Results of Simulations with Global Block Adjustment Methods

1991 ◽  
Vol 127 ◽  
pp. 399-403
Author(s):  
N. Zacharias
Keyword(s):  
Reference System ◽  
Systematic Errors ◽  
Reference Star ◽  
Star Catalog ◽  
Optical Reference ◽  
First Results

AbstractBlock adjustment (BA) simulations of an entire hemisphere show major improvements in individual as well as systematic accuracy of star positions obtained by photographic astrometry, independent of systematic errors of the reference star catalog used. Results for the accuracy estimates obtained from a patch-like plate pattern in the sky are not valid for closed plate pattern. The importance of BA methods for the realisation of a reference system is stressed.

scholarly journals Proper Motions of OB Stars in Both Hemispheres

1974 ◽  
Vol 61 ◽  
pp. 227-227
Author(s):  
Haruo Yasuda
Keyword(s):  
Southern Hemisphere ◽  
Fundamental System ◽  
Systematic Errors ◽  
Radial Velocities ◽  
Distance Scale ◽  
Proper Motions ◽  
Stellar Kinematics ◽  
Ob Stars

From a comparison between the rotational velocities derived from radial velocities and space motions of OB stars, large systematic errors of FK4 proper motions in the southern hemisphere are evaluated; these may be expected, from the known accuracy of the FK4. The error of adopted distance scale is also examined. It is suggested that meridian observations of OB stars should be extended to the southern hemisphere to further researches, not only on stellar kinematics, but also on the fundamental system.

scholarly journals LQAC-5: The fifth release of the Large Quasar Astrometric Catalogue

2019 ◽  
Vol 624 ◽  
pp. A145 ◽  
Author(s):  
J. Souchay ◽  
C. Gattano ◽  
A. H. Andrei ◽  
D. Souami ◽  
B. Coelho ◽  
...  
Keyword(s):  
A Priori ◽  
Proper Motions ◽  
Positional Accuracy ◽  
Mid Infrared ◽  
Additional Information ◽  
Complete Catalogue ◽  
Absolute Magnitudes ◽  
Celestial Sphere ◽  
First Time ◽  
Cross Match

Context. In addition to their great astrophysical interest, quasars represent quasi-ideal reference objects in the celestial sphere with, a priori, a lack of significant proper motion. Since the fourth release of the Large Quasar Astrometric Catalogue (LQAC-4), a large number of quasars have been discovered, in particular those coming from the DR14Q release of the SDSS. With the advent of the Gaia Data Release 2 (DR2), it is now also possible to fold in extremely accurate quasar positions. Aims. Following the same procedure as in the previous releases of the LQAC, our aim is to compile the large majority of the recorded quasars, with their best estimated coordinates and substantial information about their physical properties such as the redshift, multi-bands apparent, and absolute magnitudes. Emphasis is given to the results of the cross-matches with the Gaia DR2 catalogue, which considerably increases the positional accuracy. Methods. New quasars from the SDSS DR14Q release were cross-matched with the precedent LQAC-4 compilation with a 1″ search radius, which leads to 149 084 objects not present in the previous LQAC-4 release. Another cross-match was done with the Gaia DR2 catalogue, which enables us to considerably improve the positioning of these objects. For the first time, parallaxes and proper motions from the DR2, when available, are added to our compilation. Furthermore, a cross-identification of the LQAC-5 with the AllWISE survey gives additional mid-infrared information for an important percentage of objects. Results. Our final catalogue, namely the LQAC-5, contains 592 809 quasars. This represents roughly a 34% increase with respect to the number of objects recorded in the LQAC-4. Among them, 398 697 objects were found in common with the Gaia DR2, within a 1″ search radius. That corresponds to 67.26% of the whole population of the compilation. Conclusion. The LQAC-5 delivers a nearly complete catalogue of spectroscopically confirmed quasars (including a small proportion of 14 126 compact AGN’s) to the astronomical community, with the aim of giving their best equatorial coordinates with respect to the ICRF2 and with exhaustive additional information. For more than 50% of the sample, these coordinates are extracted from the very recent Gaia DR2.

scholarly journals The Hipparcos Extragalactic Link

1995 ◽  
Vol 166 ◽  
pp. 127-132 ◽  
Author(s):  
Jean Kovalevsky
Keyword(s):  
Reference Frames ◽  
Hubble Space Telescope ◽  
Visible Spectrum ◽  
Proper Motions ◽  
Time Intervals ◽  
Hipparcos Catalogue ◽  
Celestial Reference System ◽  
Celestial Reference Frame ◽  
Galactic Radio ◽  
Better Than

In conformity with the IAU resolutions on reference frames adopted in 1991, the Hipparcos catalogue will represent, in the visible spectrum, the celestial reference system defined by fixed positions of extra-galactic radio-sources. This will be realized by the strongest possible link between the IERS celestial reference frame with positions and/or proper motions of the largest possible number of Hipparcos stars determined also with respect to extragalactic objects. The data which will be used must be available before April 1995. It will include the following: positions and proper motions of radio stars observed by VLBI, VLA and MERLIN; photographic positions in fields including quasars; proper motions with respect to galaxies of the Lick, Yale, and Kiev programs, proper motions derived from pairs of photographic plates taken at large time intervals; and possibly data acquired by Hubble Space Telescope and from Earth's rotation data. The organization of the tasks within the working group is briefly described. The final accuracy of the link is expected to be of the order of, or better than, half a milliarcsecond.

scholarly journals Computation of Compilation Catalogs

1986 ◽  
Vol 109 ◽  
pp. 75-86
Author(s):  
Thomas E. Corbin
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Fundamental System ◽  
Proper Motions ◽  
The South ◽  
International Reference ◽  
The North ◽  
Naval Observatory ◽  
Made In

Currently the computation of mean positions and proper motions for the International Reference Stars (IRS) is hampered by large variations in the observational histories of the stars and lack of overlap between the magnitudes of the IRS and of the FK4. The poorest IRS observational histories are +60° to +80° in the north and −40° to −80° in the south. The much-needed extension of the fundamental system to the ninth magnitude will be made in the FK5. The Faint Fundamental Extension is currently being selected at the U. S. Naval Observatory. A proposed list of 1030 Faint Fundamental stars has been prepared for the Northern Hemisphere, and work has begun on the selection in the Southern Hemisphere.

scholarly journals Astrometric star catalogues as combination of Hipparcos/Tycho catalogues with ground-based observations

2004 ◽  
pp. 1-8 ◽  
Author(s):  
J. Vondrák
Keyword(s):  
Universal Time ◽  
Optical Observations ◽  
Proper Motions ◽  
Earth Orientation ◽  
Optical Wavelength ◽  
Primary Representation ◽  
Hipparcos Catalogue ◽  
Time Variations ◽  
Celestial Reference System ◽  
Better Than

The successful ESA mission Hipparcos provided very precise parallaxes positions and proper motions of many stars in optical wavelength. Therefore it is a primary representation of International Celestial Reference System in this wavelength. However, the shortness of the mission (less than four years) causes some problems with proper motions of the stars that are double or multiple. Therefore, a combination of the positions measured by Hipparcos satellite with ground-based observations with much longer history provides a better reference frame that is more stable in time. Several examples of such combinations are presented (ACT, TYCHO-2, FK6, GC+HIP, TYC2+HIP, ARIHIP) and briefly described. The stress is put on the most recent Earth Orientation Catalogue (EOC) that uses about 4.4 million optical observations of latitude/universal time variations (made during the twentieth century at 33 observatories in Earth orientation programmes), in combination with some of the above mentioned combined catalogues. The second version of the new catalogue EOC-2 contains 4418 objects, and the precision of their proper motions is far better than that of Hipparcos Catalogue.

scholarly journals 5 GHz Continuum Radiation from Southern Hemisphere Galactic HII Regions

1968 ◽  
Vol 21 (6) ◽  
pp. 881 ◽  
Author(s):  
FF Gardner ◽  
M Morimoto
Keyword(s):  
Southern Hemisphere ◽  
Hii Regions ◽  
Radio Sources ◽  
Positional Accuracy ◽  
Continuum Radiation ◽  
Thermal Radio ◽  
5 Ghz ◽  
Better Than ◽  
The Continuum

The continuum radiation from about 36 southern thermal radio sources has been surveyed at 6 cm wavelength with a beamwidth of 4'�2 arc, and maps are shown for 28 of these. The positional accuracy is better than l' arc.

The proper motions of the AGK 3 R and SRS Stars

1978 ◽  
Vol 48 ◽  
pp. 505-514 ◽  
Author(s):  
T. E. Corbin
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Proper Motions ◽  
Naval Observatory ◽  
The Mean ◽  
Work First ◽  
The U.S

The AGK3R and SRS are lists of reference stars containing, respectively, 21,499 stars in the Northern Hemisphere and about 20,500 stars in the Southern Hemisphere. Eleven transit circles contributed to the observations of the AGK3R. The program was a differential one based on theFK4, and the average mean epoch of observation is 1959.0. The compilation of the SRS is still in progress at the U.S. Naval Observatory. As Dr. Hughes has just explained, the SRS positions also will be referred to the system of the FK4, and the mean epochs of observation will be in the latter part of the 1960’s. My task has been to compute the proper motions for these two groups of stars that will permit the use of the observed positions away from the epochs of observation. Since the proper motions of the AGK3R stars have been completed, I will report on that work first.

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