- ID:
- ivo://CDS.VizieR/J/MNRAS/434/956
- Title:
- AT20G high-angular-resolution catalogue
- Short Name:
- J/MNRAS/434/956
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the high-angular-resolution catalogue for the Australia Telescope 20GHz (AT20G, Cat. J/MNRAS/402/2403) survey, using the high-angular-resolution 6-km antenna data at the baselines of ~4500m of the Australia Telescope Compact Array. We have used the data to produce the visibility catalogue that separates the compact active galactic nuclei (AGNs) from the extended radio sources at the 0.15arcsec angular scale, corresponding to the linear size scale of 1kpc at redshifts higher than 0.7. We find the radio population at 20GHz to be dominated by compact AGNs constituting 77% of the total sources in the AT20G. We introduce the visibility-spectra diagnostic plot, produced using the AT20G cross-matches with lower frequency radio surveys at 1GHz [the NRAO VLA Sky Survey (NVSS, Cat. VIII/65) and the Sydney University Molonglo Sky Survey (SUMSS, Cat. VIII/81)], that separates the 20GHz population into distinct sub-populations of the compact AGNs, the compact steep-spectrum (CSS) sources, the extended AGN-powered sources and extended flat-spectrum sources. The extended flat-spectrum sources include a local thermal emitting population of high-latitude planetary nebulae and also gravitational lens and binary black hole candidates among the AGNs. We find a smooth transition in properties between the CSS sources and the AGN populations. The visibility catalogue, together with the main AT20G survey, provides an estimate of angular size scales for sources in the AT20G and an estimate of the flux arising from central cores of extended radio sources. The identification of the compact AGNs in the AT20G survey provides high-quality calibrators for high-frequency radio telescope arrays and very large baseline interferometry observations.
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Search Results
1432. AT20G-MWACS catalogue
- ID:
- ivo://CDS.VizieR/J/MNRAS/476/2717
- Title:
- AT20G-MWACS catalogue
- Short Name:
- J/MNRAS/476/2717
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new broad-band radio frequency catalogue across 0.12GHz<={nu}<=20GHz created by combining data from the Murchison Widefield Array Commissioning Survey, the Australia Telescope 20GHz survey, and the literature. Our catalogue consists of 1285 sources limited by S_20GHz_>40mJy at 5{sigma}, and contains flux density measurements (or estimates) and uncertainties at 0.074, 0.080, 0.119, 0.150, 0.180, 0.408, 0.843, 1.4, 4.8, 8.6, and 20GHz. We fit a second-order polynomial in log-log space to the spectral energy distributions of all these sources in order to characterize their broad-band emission. For the 994 sources that are well described by a linear or quadratic model we present a new diagnostic plot arranging sources by the linear and curvature terms. We demonstrate the advantages of such a plot over the traditional radio colour-colour diagram. We also present astrophysical descriptions of the sources found in each segment of this new parameter space and discuss the utility of these plots in the upcoming era of large area, deep, broad-band radio surveys.
1433. AT20G-optical catalogue
- ID:
- ivo://CDS.VizieR/J/MNRAS/417/2651
- Title:
- AT20G-optical catalogue
- Short Name:
- J/MNRAS/417/2651
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our current understanding of radio-loud active galactic nuclei (AGN) comes predominantly from studies at frequencies of 5GHz and below. With the recent completion of the Australia Telescope 20GHz (AT20G) survey, we can now gain insight into the high-frequency radio properties of AGN. This paper presents supplementary information on the AT20G sources in the form of optical counterparts and redshifts. Optical counterparts were identified using the SuperCOSMOS data base and redshifts were found from either the 6dF Galaxy Survey or the literature. We also report 144 new redshifts. For AT20G sources outside the Galactic plane, 78.5% have optical identifications and 30.9% have redshift information. The optical identification rate also increases with increasing flux density. Targets which had optical spectra available were examined to obtain a spectral classification.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A93
- Title:
- AT 2020hat and AT 2020kog light curves
- Short Name:
- J/A+A/647/A93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of our monitoring campaigns of the luminous red novae (LRNe) AT 2020hat in NGC 5068 and AT 2020kog in NGC 6106. The two objects were imaged (and detected) before their discovery by routine survey operations. They show a general trend of slow luminosity rise lasting at least a few months. The subsequent major LRN outbursts were extensively followed in photometry and spectroscopy. The light curves present an initial short-duration peak, followed by a redder plateau phase. AT 2020kog is a moderately luminous event peaking at ~7x10^40^erg/s, while AT 2020hat is almost one order of magnitude fainter than AT 2020kog, although it is still more luminous than V838 Mon. In analogy with other LRNe, the spectra of AT 2020kog change significantly with time. They resemble those of type IIn supernovae at early phases, then they become similar to those of K-type stars during the plateau, and to M-type stars at very late phases. In contrast, AT 2020hat already shows a redder continuum at early epochs, and its spectrum shows the late appearance of molecular bands. A moderate-resolution spectrum of AT 2020hat taken at +37d after maximum shows a forest of narrow P Cygni lines of metals with velocities of 180 km/s, along with an Halpha emission with a full-width at half-maximum velocity of 250km/s. For AT 2020hat, a robust constraint on its quiescent progenitor is provided by archival images of the Hubble Space Telescope. The progenitor is clearly detected as a mid-K type star, with an absolute magnitude of M_F606W=-3.33+/-0.09mag and a colour of F606W-F814W=1.14+/-0.05mag, which are inconsistent with the expectations from a massive star that could later produce a core-collapse supernova. Although quite peculiar, the two objects nicely match the progenitor versus light curve absolute magnitude correlations discussed in the literature.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A134
- Title:
- ATHOS. Flux ratio based stellar parameterization
- Short Name:
- J/A+A/619/A134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The rapidly increasing number of stellar spectra obtained by existing and future large-scale spectroscopic surveys feeds a demand for fast and efficient tools for the spectroscopic determination of fundamental stellar parameters. Such tools should not only comprise customized solutions for one particular survey or instrument, but, in order to enable cross-survey comparability, they should also be capable of dealing with spectra from a variety of spectrographs, resolutions, and wavelength coverages. To meet these ambitious specifications, we developed ATHOS (A Tool for HOmogenizing Stellar parameters), a fundamentally new analysis tool that adopts easy-to-use, computationally inexpensive analytical relations tying flux ratios (FRs) of designated wavelength regions in optical spectra to the stellar parameters effective temperature (Teff), iron abundance ([Fe/H]), and surface gravity (logg). Our Teff estimator is based on FRs from nine pairs of wavelength ranges around the Balmer lines H{beta} and H{alpha}, while for [Fe/H] and logg we provide 31 and 11 FRs, respectively, which are spread between ~4800{AA} and ~6500{AA}; a region covered by most optical surveys. The analytical relations employing these FRs were trained on N=124 real spectra of a stellar benchmark sample that covers a large parameter space of Teff~=4000 to 6500K (spectral types F to K), [Fe/H]~=-4.5 to 0.3dex, and logg~=1 to 5dex, which at the same time reflects ATHOS' range of applicability. We find accuracies of 97K for Teff, 0.16dex for [Fe/H], and 0.26dex for logg, which are merely bounded by finite uncertainties in the training sample parameters. ATHOS' internal precisions can be better by up to 70%. We tested ATHOS on six independent large surveys spanning a wide range of resolutions (R~=2000 to 52000), amongst which are the Gaia-ESO and the SDSS/SEGUE surveys. The exceptionally low execution time (<30ms per spectrum per CPU core) together with a comparison to the literature parameters showed that ATHOS can successfully achieve its main objectives, in other words fast stellar parametrization with cross-survey validity, high accuracy, and high precision. These are key to homogenize the output from future surveys, such as 4MOST or WEAVE.
- ID:
- ivo://CDS.VizieR/J/A+A/632/L6
- Title:
- AT 2018hso light curves and spectra
- Short Name:
- J/A+A/632/L6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The absolute magnitudes of luminous red novae (LRNe) are intermediate between those of novae and supernovae (SNe), and show a relatively homogeneous spectro-photometric evolution. Although they were thought to derive from core instabilities in single stars, there is growing support for the idea that they are triggered by binary interaction that possibly ends with the merging of the two stars. AT 2018hso is a new transient showing transitional properties between those of LRNe and the class of intermediate-luminosity red transients (ILRTs) similar to SN 2008S. Through the detailed analysis of the observed parameters, our study support that it actually belongs to the LRN class and was likely produced by the coalescence of two massive stars. We obtained ten months of optical and near-infrared photometric monitoring, and 11 epochs of low-resolution optical spectroscopy of AT 2018hso. We compared its observed properties with those of other ILRTs and LRNe. We also inspected the archival Hubble Space Telescope (HST) images obtained about 15 years ago to constrain the progenitor properties. The light curves of AT 2018hso show a first sharp peak (reddening-corrected M_r_=13.93mag), followed by a broader and shallower second peak that resembles a plateau in the optical bands. The spectra dramatically change with time. Early-time spectra show prominent Balmer emission lines and a weak [CaII] doublet, which is usually observed in ILRTs. However, the strong decrease in the continuum temperature, the appearance of narrow metal absorption lines, the great change in the H{alpha} strength and profile, and the emergence of molecular bands support an LRN classification. The possible detection of a M_I_~8mag source at the position of AT 2018hso in HST archive images is consistent with expectations for a pre-merger massive binary, similar to the precursor of the 2015 LRN in M101. We provide reasonable arguments to support an LRN classification for AT 2018hso. This study reveals growing heterogeneity in the observables of LRNe than has been thought previously, which is a challenge for distinguishing between LRNe and ILRTs. This suggests that the entire evolution of gap transients needs to be monitored to avoid misclassifications.
- ID:
- ivo://nasa.heasarc/atlasd2cpt
- Title:
- ATLargeAreaSurvey(ATLAS)CDF-S&ELAIS-S11.4-GHzDR2ComponentsCatalog
- Short Name:
- ATLASD2CPT
- Date:
- 18 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table derives from the first of two papers describing the second data release (DR2) of the Australia Telescope Large Area Survey (ATLAS) at 1.4 GHz. This survey comprises deep wide-field observations in total intensity, linear polarization, and circular polarization over the Chandra Deep Field-South (CDF-S) and European Large Area Infrared Space Observatory Survey (ELAIS)-South 1 regions. DR2 improves upon the first data release by maintaining consistent data reductions across the two regions, including polarization analysis, and including differential number counts in total intensity and linear polarization. Typical DR2 sensitivities across the mosaicked multi-pointing images are 30 µJy per beam at approximately 12 arcseconds by 6 arcseconds resolution over a combined area of 6.4 square degrees. In their paper, the authors present detailed descriptions of their data reduction and analysis procedures, including corrections for instrumental effects such as positional variations in image sensitivity, bandwidth smearing with a non-circular beam, and polarization leakage, and application of the BLOBCAT source extractor. They present the DR2 images and catalogs of components (discrete regions of radio emission) and sources (groups of physically associated radio components), and describe new analytic methods to account for resolution bias and Eddington bias when constructing differential number counts of radio components. The authors use the term 'component' to refer to an isolated region of emission that is best described by a single 2D elliptical Gaussian. Blended regions of contiguous emission may consist of multiple individual components. Following the terminology from Hales et al. (2012, MNRAS, 425, 979), a 'blob' is an agglomerated island of pixels above an SNR cutoff, which may encapsulate a single component or a blended region of emission. In Section 6 of the reference paper, the authors use the term 'source' to refer to single or multiple components belonging to the same astronomical object. This HEASARC table contains the ATLAS 1.4 GHz DR2 component catalog, a portion of which is displayed in Table A1 of the reference paper for guidance regarding its form and content. The catalog lists a total of 2,588 components in total intensity and linear polarization; no components were discovered in circular polarization. A list of the ATLAS 1.4 GHz DR2 sources, a portion of which is displayed in Table B1 of the reference paper for guidance regarding its form and content, is not included in this HEASARC table. This table was created by the HEASARC in October 2014 based on an electronic version of Table A1 from the reference paper which was obtained from the MNRAS web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/atlascscpt
- Title:
- AT Large Area Survey (ATLAS) CDF-S/SWIRE 1.4-GHz Components Catalog
- Short Name:
- ATLASCSCPT
- Date:
- 18 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains some of the first results from the Australia Telescope Large Area Survey (ATLAS), which consists of deep 1.4-GHz radio observations of a 3.7 deg<sup>2</sup> field surrounding the Chandra Deep Field-South (CDF-S), largely coincident with the infrared Spitzer Wide-Area Infrared Extragalactic (SWIRE) Survey. A total of 784 radio components are identified, corresponding to 726 distinct radio sources, nearly all of which are identified with SWIRE sources in the companion table ATLASCSID. Of the radio sources with measured redshifts, most lie in the redshift range 0.5 to 2 and include both star-forming galaxies and active galactic nuclei. The authors identify a rare population of infrared-faint radio sources that are bright at radio wavelengths but are not seen in the available optical, infrared, or X-ray data. Such rare classes of sources can only be discovered in wide, deep surveys such as this. The radio observations where made on 2002 Apr 4-27, Aug 24-29 and 2004 Jan 7-12, Feb 1-5, Jun 6-12 and Nov 24-30, with the Australia Telescope Compact Array (ATCA). The observations in 2002 were made in a mosaic of 7 overlapping fields, for a total of 149 hours of integration time, or 21.3 hours per pointing. The observations in 2004 were taken in the AT mosaic mode, in which the array was cycled around 21 pointing centers They total 173 hours of integration time, or 8.2 hours per pointing. All observations were made with two 128-MHz bands, centered on frequencies of 1344 and 1472 MHz. This table contains the list of 784 radio components given in Table 4 of the reference paper. The authors define a radio 'component' as a region of radio emission identified in the source extraction process. They define a radio 'source' as one or more radio components that appear to be physically connected and that probably correspond to one galaxy. Thus, the authors count a classical triple radio-loud source as being a radio source consisting of three radio components, but count a pair of interacting starburst galaxies as being two sources, each with one radio component. This table was created by the HEASARC in August 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/AJ/132/2409">CDS Catalog J/AJ/132/2409</a> file table4.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/atlascsid
- Title:
- AT Large Area Survey (ATLAS) CDF-S/SWIRE ID and Classification Catalog
- Short Name:
- ATLASCSID
- Date:
- 18 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains some of the first results from the Australia Telescope Large Area Survey (ATLAS), which consists of deep radio observations of a 3.7 deg<sup>2</sup> field surrounding the Chandra Deep Field-South (CDF-S), largely coincident with the infrared Spitzer Wide-Area Infrared Extragalactic (SWIRE) Survey. A total of 784 radio components are identified (see the companion table ATLASCSCPT), corresponding to 726 distinct radio sources, nearly all of which are identified with SWIRE sources. Of the radio sources with measured redshifts, most lie in the redshift range 0.5 to 2 and include both star-forming galaxies and active galactic nuclei. The authors identify a rare population of infrared-faint radio sources that are bright at radio wavelengths but are not seen in the available optical, infrared, or X-ray data. Such rare classes of sources can only be discovered in wide, deep surveys such as this. The radio observations where made on 2002 Apr 4-27, Aug 24-29 and 2004 Jan 7-12, Feb 1-5, Jun 6-12 and Nov 24-30, with the Australia Telescope Compact Array (ATCA). The observations in 2002 were made in a mosaic of 7 overlapping fields, for a total of 149 hours of integration time, or 21.3 hours per pointing. The observations in 2004 were taken in the AT mosaic mode, in which the array was cycled around 21 pointing centers They total 173 hours of integration time, or 8.2 hours per pointing. All observations were made with two 128-MHz bands, centered on frequencies of 1344 and 1472 MHz. This table contains the list of 726 radio sources and their cross-identifications at optical and infrared wavelengths which were given in Table 6 of the reference paper. The authors define a radio 'component' as a region of radio emission identified in the source extraction process. They define a radio 'source' as one or more radio components that appear to be physically connected and that probably correspond to one galaxy. Thus, the authors count a classical triple radio-loud source as being a radio source consisting of three radio components, but count a pair of interacting starburst galaxies as being two sources, each with one radio component. his table was created by the HEASARC in August 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/AJ/132/2409">CDS Catalog J/AJ/132/2409</a> file table6.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/atlas5p5gh
- Title:
- AT Large Area Survey (ATLAS) E-CDF-S 5.5-GHz Components Catalog
- Short Name:
- ATLAS5P5GH
- Date:
- 18 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Star-forming galaxies are thought to dominate the sub-mJy radio population, but recent work has shown that low-luminosity active galactic nuclei (AGNs) can still make a significant contribution to the faint radio source population. Spectral indices are an important tool for understanding the emission mechanism of the faint radio sources. The authors have observed the extended Chandra Deep Field South at 5.5 GHz using a mosaic of 42 pointings with the Australia Telescope Compact Array (ATCA). Their image reaches an almost uniform sensitivity of ~ 12 µJy (µJy) rms over 0.25 deg<sup>2</sup> with a restoring beam of 4.9 arcsec x 2.0 arcsec, making the ATLAS 5.5-GHz survey one of the deepest 6-cm surveys to date. This table contains the 5.5 GHz catalog of 142 source components corresponding to the 123 sources in this field: the source counts from this field are discussed in the reference paper. This table was created by the HEASARC in February 2013 based on the electronic version of Table 1 from the reference paper which was obtained from the MNRAS web site. This is a service provided by NASA HEASARC .
