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 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 Wading Through the Quagmire of Schmidt-Plate Coordinate Systematics

1998 ◽  
Vol 179 ◽  
pp. 384-385 ◽  
Author(s):  
C.-L Lu ◽  
I. Platais ◽  
T.M. Girard ◽  
V. Kozhurina-Platais ◽  
W.F. Van Altena ◽  
...  
Keyword(s):  
Proper Motion ◽  
San Juan ◽  
Proper Motions ◽  
Positional Accuracy

We attempted to quantify the magnitude-dependent systematics in a sample of Schmidt plates by comparison to positions from the Yale/San Juan Southern Proper Motion program which offers star positions and absolute proper motions down to B = 18 with a mean density of about 50 stars per square degree and a positional accuracy of 0.1″ (Platais et al. 1995).

scholarly journals Proper Motions Referred to Faint Galaxies

1986 ◽  
Vol 7 ◽  
pp. 89-92
Author(s):  
W. F. van Altena ◽  
T. Girard ◽  
C. E. López ◽  
A. R. Klemola ◽  
B. F. Jones ◽  
...  
Keyword(s):  
Proper Motion ◽  
Reference Frames ◽  
Photographic Plate ◽  
Proper Motions ◽  
Plate Material ◽  
Present Epoch ◽  
Magnitude Range ◽  
Large Numbers ◽  
Material Forming ◽  
Partial Extension

The Lick Northern Proper Motion (NPM) and the Yale-San Juan Southern Proper Motion (SPM) programs have been described on several occasions (Wright 1950; Deutsch and Klemola 1974; Vasilevskis 1973; and Wesselink 1974). The two programs represent an attempt to measure the coordinates and proper motions, with respect to the extragalactic reference frames, for large numbers of stars representing most of the astrophysically-recognized classes. The photographic plate material forming the basis of the NPM program derives from the first (1947-1954) and second (1970-present) epoch phases for 1246 fields with the Lick 51 cm Carnegie double-astrograph for centers at -20° and northward (Shane and Wirtanen 1967). A southern supplement of 144 additional fields takes the program to -30°. The SPM consists of 632 fields with centers at -20° and southward. The first epoch plates were taken between 1965 and 1974 and a partial extension of 72 fields to more northerly declinations is essentially complete. One short and one long exposure permit the measurement of positions and approximate photometry for selected stars and reference galaxies over the blue magnitude range from about 8 to 17-18.

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 Astrometric Programs by the New Hamburg Plate Measuring Machine

1994 ◽  
Vol 161 ◽  
pp. 173-176
Author(s):  
Chr. de Vegt ◽  
L. Winter ◽  
N. Zacharias
Keyword(s):  
Reference Frame ◽  
Northern Hemisphere ◽  
High Accuracy ◽  
Proper Motions ◽  
Sky Surveys ◽  
Unique Data ◽  
Large Sets ◽  
Measuring Machine ◽  
First Time

With the new Hamburg astrometric measuring machine, large sets of plates can be digitized very quickly with submicrometer accuracy. In particular about 2000 plates of the AGK2-catalog, mean epoch 1930, can be remeasured now for the first time to their limiting magnitude, about B = 11. The new AGK2-data therefore will cover practically the whole AC-catalog and TYCHO-stars in the northern hemisphere. All plates will be reduced using the HIPPARCOS results as the reference frame when available in 1996. The new AGK2-data will provide a unique data base for the determination of high accuracy proper motions (about 2 mas/yr) of all TYCHO stars in the northern hemisphere. Furthermore, for the first time a dense reference frame for a final reduction of the Astrographic Catalog (AC) and the large deep sky surveys will be generated by this catalog. The inferior situation in the southern hemisphere will be addressed briefly.

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 Proper Motions in the Bulge: Looking Through Plaut's Low Extinction Window

1998 ◽  
Vol 179 ◽  
pp. 223-224
Author(s):  
R.A. Méndez ◽  
R.M. Rich ◽  
W.F. Van Altena ◽  
T.M. Girard ◽  
S. Van Den Bergh ◽  
...  
Keyword(s):  
Proper Motion ◽  
Main Sequence ◽  
Proper Motions ◽  
Galactic Bulge ◽  
Plate Material

We are conducting the deepest and largest photographic proper-motion survey ever undertaken of the Galactic bulge. Our first-epoch plate material (from 1972-3) goes deep enough (Vlim ∼ 22) to reach below the bulge main-sequence turnoff. These plates cover an area of approximately 25′ × 25′ of the bulge in the low-extinction (Av ∼ 0.8 mag) Plaut field at l= 0°, b= −8°, approximately 1 kpc south of the nucleus. This is the point at which the transition between bulge and halo populations likely occurs and is, therefore, an excellent location to study the interface between the dense metal-rich bulge and the metal-poor halo.

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 Automated Proper Motion Survey: Data Reduction and Initial System Performance

1970 ◽  
Vol 7 ◽  
pp. 26-47 ◽  
Author(s):  
A. E. La Bonte
Keyword(s):  
Data Reduction ◽  
Proper Motion ◽  
System Performance ◽  
Processing Time ◽  
The Other ◽  
Photographic Emulsion ◽  
Proper Motions ◽  
Plate Material ◽  
Schmidt Telescope ◽  
Plate Center

The Automated Proper Motion Survey (APMS) has three broad goals-accuracy, completeness, and efficiency in the discovery and measurement of stellar proper motions on pairs of red-sensitive photographic star plates taken with the forty-eight inch Schmidt telescope. The specific range of motions sought is from 0.1 to 2.5 seconds-of-arc per year. The lower limit of 0.1 arc sec/year is consistent with the inherent uncertainties in the photographic emulsion and the typical epoch difference between plate exposures. At the opposite end of the scale, extension of the search radius beyond that corresponding to 2.5 arc sec/year would result in a prohibitively large number of spurious matches and a significant increase in processing time while yielding extremely few (though individually interesting) additional stellar motions. The specific range of stellar magnitudes sought is from 12 to 19 red. Significant motions for stars brighter than the limit mred = 12 are already fairly well documented and the corresponding bright Schmidt images begin to show extensive contamination from diffraction spikes, “blazes” radially away from the plate center, and photographic “bloom”. At the other limit, although images of stars fainter than mred = 19 are visually discernible on the plates (the plate limit is typically mred= 20), inspection of the faintest images reveals that they are amorphous and often quite asymmetric clusters of photographic grain. Thus, both the motion limits and the magnitude limits for the survey have been selected to cover the range of reliable and largely unexplored data on the plate material. The implementation of APMS, then, is tailored to these goals and ranges.

scholarly journals Faint Reference Stars

1990 ◽  
Vol 141 ◽  
pp. 433-442
Author(s):  
Thomas E. Corbin ◽  
Sean E. Urban
Keyword(s):  
Working Group ◽  
Reference Star ◽  
Proper Motions ◽  
International Reference ◽  
The Mean ◽  
Major Reference

Three major reference star projects have been completed recently at the USNO: the Southern International Reference Stars (SIRS − 19, 827 stars) the southern part of the Faint Fundamentals (1,169 stars) and the Astrographic Catalog Reference Stars (ACRS - 325,416 stars). The compilation of the mean positions and proper motions of each is discussed. Reports on the progress of the USNO's Pole-to-Pole Fundamental Program and the Working Group on Star Lists are also presented.

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