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 LQAC-4: Fourth release of the Large Quasar Astrometric Catalogue

2018 ◽  
Vol 614 ◽  
pp. A140 ◽  
Author(s):  
C. Gattano ◽  
A. H. Andrei ◽  
B. Coelho ◽  
J. Souchay ◽  
C. Barache ◽  
...  
Keyword(s):  
Proper Motion ◽  
A Priori ◽  
Point Of View ◽  
Additional Information ◽  
The Third ◽  
Complete Catalogue ◽  
Absolute Magnitudes ◽  
Celestial Sphere ◽  
The Individual ◽  
Cross Match

Context. From an astrometric point of view, quasars constitute the best and almost ideal reference objects in the celestial sphere, with a priori no significant proper motion. Since the third release of the Large Quasar Astrometric Catalogue (LQAC-3), a large number of quasars have been discovered, in particular those coming from the DR12Q release of the SDSS. Moreover, for cross-matched objects, we have taken advantage of the very accurate determinations of the quasars identified within the recent Gaia DR1 catalogue. Aims. Following the same procedure as in the three previous releases of the LQAC, our aim is to compile the large majority of all the quasars recorded so far. Our goal is to record their best coordinates and substantial information concerning their physical properties such as the redshift as well as multi-bands apparent and absolute magnitudes. Emphasis is given to the results of the cross-matches with the Gaia DR1 catalogue. Methods. New quasars coming from the DR12Q release were cross-matched with the precedent LQAC-3 compilation with a 1′′ search radius, in order to add the objects without counterpart to the LQAC-4 compilation. A similar cross-match was done with Gaia DR1 to identify the known quasars detected by Gaia. This enables one to improve significantly the positioning of these objects, and in parallel to study the astrometric performance of the individual catalogues of the LQAC-4 compilation. Finally, a new method was used to determine absolute magnitudes. Results. Our final catalogue, called LQAC-4, contains 443 725 objects. This is roughly 37.82% more than the number of objects recorded in the LQAC-3. Among them, 249 071 were found in common with the Gaia DR1, with a 1′′ search radius. That corresponds to 56.13% of the whole population in the compilation. Conclusions. The LQAC-4 delivers to the astronomical community a nearly complete catalogue of spectroscopically confirmed quasars (including a small proportion of compact AGNs), 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 come from the very recent Gaia DR1.

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).

Fractal analysis in biology and medicine

2020 ◽  
pp. 85-92
Keyword(s):  
Fractal Analysis ◽  
A Priori ◽  
Research Work ◽  
Structure And Function ◽  
Review Article ◽  
Living Systems ◽  
Modern Biology ◽  
Additional Information ◽  
Important Additional Information ◽  
And Function

The review article discusses the possibilities of using fractal mathematical analysis to solve scientific and applied problems of modern biology and medicine. The authors show that only such an approach, related to the section of nonlinear mechanics, allows quantifying the chaotic component of the structure and function of living systems, that is a priori important additional information and expands, in particular, the possibilities of diagnostics, differential diagnosis and prediction of the course of physiological and pathological processes. A number of examples demonstrate the specific advantages of using fractal analysis for these purposes. The conclusion can be made that the expanded use of fractal analysis methods in the research work of medical and biological specialists is promising.

scholarly journals Diva - A Small Satellite for Global Astrometry and Photometry

1998 ◽  
Vol 11 (1) ◽  
pp. 583-583
Author(s):  
S. Röser ◽  
U. Bastian ◽  
K.S. de Boer ◽  
E. Høg ◽  
E. Schilbach ◽  
...  
Keyword(s):  
High Precision ◽  
Wavelength Range ◽  
Fizeau Interferometer ◽  
Proper Motions ◽  
Small Satellite ◽  
Short Overview ◽  
Photometric Observations ◽  
Photometric Measurements ◽  
First Time ◽  
Astronomy And Astrophysics

DIVA (Double Interferometer for Visual Astrometry) is a Fizeau interferometer on a small satellite. It will perform astrometric and photometric observations of at least 4 million stars. A launch in 2002 and a minimum mission length of 24 months are aimed at. A detailed description of the experiment can be obtained from the DIVA homepage at http://www.aip.de:8080/᷉dso/diva. An overview is given by Röser et al., 1997. The limiting magnitude of DIVA is about V = 15 for spectral types earlier than M0, but drops to about V = 17.5 for stars later than M5. Table 1 gives a short overview on DIVA’s performance. DIVA will carry out a skysurvey complete to V = 12.5. For the first time this survey will comprise precise photometry in at least 8 bands in the wavelength range from 400 to 1000 nm. DIVA will improve parallaxes by a factor of 3 compared to Hipparcos; proper motions by at least a factor of 2 and, in combination with the Hipparcos observations, by a factor of 10 for Hipparcos stars. At least 30 times asmany stars as Hipparcos will be observed, and doing this DIVA will fill the gap in observations between Hipparcos and GAIA. DIVA’s combined astrometric and photometric measurements of high precision will have important impacts on astronomy and astrophysics in the next decade.

Machine vision-based sensing for helicopter flight control

Robotica ◽  
2000 ◽  
Vol 18 (3) ◽  
pp. 299-303 ◽  
Author(s):  
Carl-Henrik Oertel
Keyword(s):  
Machine Vision ◽  
Measurement System ◽  
Flight Control ◽  
A Priori ◽  
Image Data ◽  
Two Dimensional ◽  
Position Measurement ◽  
Additional Information ◽  
Helicopter Flight ◽  
Template Tracking

Machine vision-based sensing enables automatic hover stabilization of helicopters. The evaluation of image data, which is produced by a camera looking straight to the ground, results in a drift free autonomous on-board position measurement system. No additional information about the appearance of the scenery seen by the camera (e.g. landmarks) is needed. The technique being applied is a combination of the 4D-approach with two dimensional template tracking of a priori unknown features.

scholarly journals Proper motions of young stellar outflows in the mid-infrared with Spitzer II HH 377/Cep E

2014 ◽  
Vol 16 (10) ◽  
pp. 105008 ◽  
Author(s):  
A Noriega-Crespo ◽  
A C Raga ◽  
A Moro-Martín ◽  
N Flagey ◽  
S J Carey
Keyword(s):  
Proper Motions ◽  
Mid Infrared ◽  
Stellar Outflows

A review of Sharp's types of Aleochara from Latin America (Coleoptera: Staphylinidae)

1989 ◽  
Vol 20 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Jan Klimaszewski
Keyword(s):  
Latin America ◽  
South America ◽  
North American ◽  
Additional Information ◽  
First Time

AbstractA review of David Sharp's types of Aleochara from Mexico, and Central and South America is presented. Nineteen species are treated here, one of which is described as new (A. felixiana), seven are redescribed [A. angusticeps Sharp, A. funestior Sharp, A. mexicana Sharp, A. oxypodia Sharp, A. simulatrix Sharp, A. gracilis (Sharp), and A. duplicata (Sharp)] and one [A. miradoris Sharp] is put in synonymy under A. mexicana Sharp. The remaining ten species were treated in my 1984-revision of North American Aleochara but are here included in a checklist with references to description, redescription, and illustrations. Some additional information is provided for previously synonymized A. torquata Sharp (= A. sallaei Sharp), and for A. quadrata Sharp. Illustrations of genitalic structures of both sexes are provided for the first time for the seven redescribed species. Lectotypes are designated for A. angusticeps, A. duplicata, A. funestior, A. mexicana, and A. oxypodia.

scholarly journals What do women know about breast density? A public screening program perspective

2020 ◽  
Author(s):  
Monique Robertson ◽  
Ellie C Darcey ◽  
Evenda K Dench ◽  
Louise Keogh ◽  
Kirsty McLean ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Breast Density ◽  
Screening Program ◽  
Mammographic Screening ◽  
Descriptive Data ◽  
Additional Information ◽  
Dense Breasts ◽  
Increased Risk ◽  
Main Message ◽  
First Time

AbstractBackgroundThis study assesses knowledge of breast density, one of breast cancer’s strongest risk factors, in women attending a public mammographic screening program in Western Australia that routinely notifies women if they have dense breasts.MethodsSurvey data was collected from women who were notified they have dense breasts and women who had not (controls). Descriptive data analysis was used to summarize responses.ResultsOf the 6183 women surveyed, over 85% of notified women knew that breast density makes it difficult to see cancer on a mammogram (53.9% in controls). A quarter of notified women knew that having dense breasts puts women at increased risk for breast cancer (13.2% in controls). Overall, 50.1% of notified women indicated that they thought the amount of information provided was “just right” and 24.9% thought it was “too little”, particularly women notified for the first time (32.1%).ConclusionThe main message of reduced sensitivity of mammography in women with dense breasts provided by the screening program appears to be getting though. However, women are largely unaware that increased breast density is associated with increased risk. Women notified of having dense breasts for the first time could potentially benefit from additional information.

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).

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