scholarly journals The second Herschel–ATLAS Data Release – III. Optical and near-infrared counterparts in the North Galactic Plane field

2018 ◽  
Vol 476 (1) ◽  
pp. 961-978 ◽  
Author(s):  
C Furlanetto ◽  
S Dye ◽  
N Bourne ◽  
S Maddox ◽  
L Dunne ◽  
...  
Keyword(s):  
Likelihood Ratio ◽  
Near Infrared ◽  
Galactic Plane ◽  
Ratio Method ◽  
Large Area ◽  
Sky Survey ◽  
Public Data ◽  
Data Release ◽  
North Galactic ◽  
Likelihood Ratio Method

Abstract This paper forms part of the second major public data release of the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS). In this work, we describe the identification of optical and near-infrared counterparts to the submillimetre detected sources in the 177 deg2 North Galactic Plane (NGP) field. We used the likelihood ratio method to identify counterparts in the Sloan Digital Sky Survey and in the United Kingdom InfraRed Telescope Imaging Deep Sky Survey within a search radius of 10 arcsec of the H-ATLAS sources with a 4σ detection at 250 μm. We obtained reliable (R ≥ 0.8) optical counterparts with r < 22.4 for 42 429 H-ATLAS sources (37.8 per cent), with an estimated completeness of 71.7 per cent and a false identification rate of 4.7 per cent. We also identified counterparts in the near-infrared using deeper K-band data which covers a smaller ∼25 deg2. We found reliable near-infrared counterparts to 61.8 per cent of the 250-μm-selected sources within that area. We assessed the performance of the likelihood ratio method to identify optical and near-infrared counterparts taking into account the depth and area of both input catalogues. Using catalogues with the same surface density of objects in the overlapping ∼25 deg2 area, we obtained that the reliable fraction in the near-infrared (54.8 per cent) is significantly higher than in the optical (36.4 per cent). Finally, using deep radio data which covers a small region of the NGP field, we found that 80–90 per cent of our reliable identifications are correct.

scholarly journals The Sloan Digital Sky Survey Quasar Catalog: Fourteenth data release

2018 ◽  
Vol 613 ◽  
pp. A51 ◽  
Author(s):  
Isabelle Pâris ◽  
Patrick Petitjean ◽  
Éric Aubourg ◽  
Adam D. Myers ◽  
Alina Streblyanska ◽  
...  
Keyword(s):  
Emission Line ◽  
Near Infrared ◽  
Wavelength Region ◽  
Principal Component ◽  
Sloan Digital Sky Survey ◽  
Large Area ◽  
Robust Identification ◽  
Broad Absorption Line ◽  
Sky Survey ◽  
Data Release

We present the data release 14 Quasar catalog (DR14Q) from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) of the Sloan Digital Sky Survey IV (SDSS-IV). This catalog includes all SDSS-IV/eBOSS objects that were spectroscopically targeted as quasar candidates and that are confirmed as quasars via a new automated procedure combined with a partial visual inspection of spectra, have luminosities Mi [z = 2] < −20.5 (in a Λ CDM cosmology with H0 = 70 km s−1 Mpc−1, Ω M =0.3, and Ω Λ = 0.7), and either display at least one emission line with a full width at half maximum larger than 500 km s−1 or, if not, have interesting/complex absorption features. The catalog also includes previously spectroscopically-confirmed quasars from SDSS-I, II, and III. The catalog contains 526 356 quasars (144 046 are new discoveries since the beginning of SDSS-IV) detected over 9376 deg2 (2044 deg2 having new spectroscopic data available) with robust identification and redshift measured by a combination of principal component eigenspectra. The catalog is estimated to have about 0.5% contamination. Redshifts are provided for the Mg II emission line. The catalog identifies 21 877 broad absorption line quasars and lists their characteristics. For each object, the catalog presents five-band (u, g, r, i, z) CCD-based photometry with typical accuracy of 0.03 mag. The catalog also contains X-ray, ultraviolet, near-infrared, and radio emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra, covering the wavelength region 3610–10 140 Å at a spectral resolution in the range 1300 < R < 2500, can be retrieved from the SDSS Science Archiver Server.

scholarly journals The LOFAR Two-metre Sky Survey

2019 ◽  
Vol 622 ◽  
pp. A2 ◽  
Author(s):  
W. L. Williams ◽  
M. J. Hardcastle ◽  
P. N. Best ◽  
J. Sabater ◽  
J. H. Croston ◽  
...  
Keyword(s):  
High Resolution ◽  
Value Added ◽  
Ratio Method ◽  
Statistical Techniques ◽  
Radio Sources ◽  
Visual Classification ◽  
Sky Survey ◽  
Data Release ◽  
Statistical Identification ◽  
Likelihood Ratio Method

The LOFAR Two-metre Sky Survey (LoTSS) is an ongoing sensitive, high-resolution 120–168 MHz survey of the northern sky with diverse and ambitious science goals. Many of the scientific objectives of LoTSS rely upon, or are enhanced by, the association or separation of the sometimes incorrectly catalogued radio components into distinct radio sources and the identification and characterisation of the optical counterparts to these sources. We present the source associations and optical and/or IR identifications for sources in the first data release, which are made using a combination of statistical techniques and visual association and identification. We document in detail the colour- and magnitude-dependent likelihood ratio method used for statistical identification as well as the Zooniverse project, called LOFAR Galaxy Zoo, used for visual classification. We describe the process used to select which of these two different methods is most appropriate for each LoTSS source. The final LoTSS-DR1-IDs value-added catalogue presented contains 318 520 radio sources, of which 231 716 (73%) have optical and/or IR identifications in Pan-STARRS and WISE.

Predicting Fetal Chromosome Anomalies in the First Trimester Using Pregnancy Associated Plasma Protein-A: A Comparison of Statistical Methods

1993 ◽  
Vol 32 (02) ◽  
pp. 175-179 ◽  
Author(s):  
B. Brambati ◽  
T. Chard ◽  
J. G. Grudzinskas ◽  
M. C. M. Macintosh
Keyword(s):  
Logistic Regression ◽  
General Population ◽  
Likelihood Ratio ◽  
False Positive ◽  
False Positive Rate ◽  
Ratio Method ◽  
Detection Rates ◽  
Gaussian Distributions ◽  
Positive Rate ◽  
Likelihood Ratio Method

Abstract:The analysis of the clinical efficiency of a biochemical parameter in the prediction of chromosome anomalies is described, using a database of 475 cases including 30 abnormalities. A comparison was made of two different approaches to the statistical analysis: the use of Gaussian frequency distributions and likelihood ratios, and logistic regression. Both methods computed that for a 5% false-positive rate approximately 60% of anomalies are detected on the basis of maternal age and serum PAPP-A. The logistic regression analysis is appropriate where the outcome variable (chromosome anomaly) is binary and the detection rates refer to the original data only. The likelihood ratio method is used to predict the outcome in the general population. The latter method depends on the data or some transformation of the data fitting a known frequency distribution (Gaussian in this case). The precision of the predicted detection rates is limited by the small sample of abnormals (30 cases). Varying the means and standard deviations (to the limits of their 95% confidence intervals) of the fitted log Gaussian distributions resulted in a detection rate varying between 42% and 79% for a 5% false-positive rate. Thus, although the likelihood ratio method is potentially the better method in determining the usefulness of a test in the general population, larger numbers of abnormal cases are required to stabilise the means and standard deviations of the fitted log Gaussian distributions.

scholarly journals Faint Standards for ZYJHK from the UKIDSS and VISTA Surveys

2020 ◽  
Vol 493 (2) ◽  
pp. 2568-2595
Author(s):  
S K Leggett ◽  
Nicholas J G Cross ◽  
Nigel C Hambly
Keyword(s):  
Near Infrared ◽  
Variable Stars ◽  
Calibration Data ◽  
Infrared Telescope ◽  
Final Sample ◽  
Sky Survey ◽  
Data Release ◽  
Deep Survey ◽  
Large Telescopes ◽  
Astrometric Data

ABSTRACT The currently defined ‘United Kingdom Infrared Telescope (UKIRT) Faint Standards’ have JHK magnitudes between 10 and 15, with Kmedian = 11.2. These stars will be too bright for the next generation of large telescopes. We have used multi-epoch observations taken as part of the UKIRT Infrared Deep Sky Survey (UKIDSS) and the Visible and Infrared Survey Telescope for Astronomy (VISTA) surveys to identify non-variable stars with JHK magnitudes in the range 16–19. The stars were selected from the UKIDSS Deep Extragalactic Survey and Ultra Deep Survey, the WFCAM calibration data (WFCAMCAL08B), the VISTA Deep Extragalactic Observations (VIDEO), and UltraVISTA. Sources selected from the near-infrared databases were paired with the Pan-STARRS Data Release 2 of optical to near-infrared photometry and the Gaia astrometric Data Release 2. Colour indices and other measurements were used to exclude sources that did not appear to be simple single stars. From an initial selection of 169 sources, we present a final sample of 81 standard stars with ZYJHK magnitudes, or a subset, each with 20 to 600 observations in each filter. The new standards have Ksmedian = 17.5. The relative photometric uncertainty for the sample is &lt;0.006 mag and the absolute uncertainty is estimated to be ≲ 0.02 mag. The sources are distributed equatorially and are accessible from both hemispheres.

Sign in / Sign up

Export Citation Format

Share Document