- ID:
- ivo://nasa.heasarc/ami10c15gz
- Title:
- 10C Survey at 15.7 GHz Radio Source Catalog
- Short Name:
- AMI10C15GZ
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- In a previous paper (AMI Consortium 2011, MNRAS, 415, 2699: Paper I), the observational, mapping and source-extraction techniques used for the Tenth Cambridge (10C) Survey of Radio Sources were described. Here, the first results from the survey, carried out using the Arcminute Microkelvin Imager (AMI) Large Array (LA) at an observing frequency of 15.7 GHz, are presented. The survey fields cover an area of ~ 27 deg<sup>2</sup> to a flux-density completeness of 1 mJy. Results for some deeper areas, covering ~ 12 deg<sup>2</sup>, which are wholly contained within the total areas and complete to 0.5 mJy, are also presented. The completeness for both areas is estimated to be at least 93 per cent. The 10C survey is the deepest radio survey of any significant extent (>~ 0.2 deg<sup>2</sup>) above 1.4 GHz. The 10C source catalogue contains 1897 entries detected above a flux density threshold of > 4.62 sigma, and is available here and at the authors' web site <a href="http://www.mrao.cam.ac.uk/surveys/10C">http://www.mrao.cam.ac.uk/surveys/10C</a>. The source catalog has been combined with that of the Ninth Cambridge Survey to calculate the 15.7-GHz source counts. A broken power law is found to provide a good parametrization of the differential count between 0.5 mJy and 1 Jy. The measured source count has been compared with that predicted by de Zotti et al. (2005, A&A, 431, 893, and the model is found to display good agreement with the data at the highest flux densities. However, over the entire flux-density range of the measured count (0.5 mJy to 1 Jy), the model is found to underpredict the integrated count by ~ 30 per cent. Entries from the source catalog have been matched with those contained in the catalogues of the NRAO VLA Sky Survey and the Faint Images of the Radio Sky at Twenty-cm survey (both of which have observing frequencies of 1.4 GHz). This matching provides evidence for a shift in the typical 1.4-GHz spectral index to 15.7-GHz spectral index of the 15.7-GHz-selected source population with decreasing flux density towards sub-mJy levels - the spectra tend to become less steep. Automated methods for detecting extended sources, developed in Paper I, have been applied to the data; ~ 5 per cent of the sources are found to be extended relative to the LA-synthesized beam of ~ 30 arcsec. Investigations using higher resolution data showed that most of the genuinely extended sources at 15.7 GHz are classical doubles, although some nearby galaxies and twin-jet sources were also identified. This table was created by the HEASARC in August 2011 based on an electronic version of Table 1 of the reference paper which was obtained from the 10C Survey web site <a href="http://www.mrao.cam.ac.uk/surveys/10C/">http://www.mrao.cam.ac.uk/surveys/10C/</a>. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/cygob2cxo2
- Title:
- Cygnus OB2 Association Chandra X-Ray Point Source Catalog 2
- Short Name:
- CYGOB2CXO2
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a catalog of 1696 X-ray sources detected in the massive star-forming region (SFR) Cygnus OB2 and extracted from two archival Chandra observations of the center of the region. A deep source extraction routine, exploiting the low background rates of Chandra observations was employed to maximize the number of sources extracted. Observations at other wavelengths were used to identify low count-rate sources and remove likely spurious sources. Monte Carlo simulations were also used to assess the authenticity of these sources. X-ray spectra were fitted with thermal plasma models to characterize the objects and X-ray light curves were analyzed to determine their variability. The authors used a Bayesian technique to identify optical or near-IR counterparts for 1501 (89%) of our sources, using deep observations from the INT Photometric H-alpha Survey, the Two Micron All Sky Survey (2MASS), and the UKIRT Infrared Deep Sky Survey-Galactic Plane Survey. 755 (45%) of these objects have six-band r', H-alpha, i', J, H, and K optical and near-IR photometry. From an analysis of the Poisson false-source probabilities for each source they estimate that their X-ray catalog includes <1% of false sources, and an even lower fraction when only sources with optical or near-IR associations are considered. A Monte Carlo simulation of the Bayesian matching scheme allows this method to be compared to more simplified matching techniques and enables the various sources of error to be quantified. The catalog of 1696 objects presented here includes X-ray broad-band fluxes, spectral model fits, and optical and near-IR photometry in what is one of the largest X-ray catalogs of a single SFR to date. The high number of stellar X-ray sources detected from relatively shallow observations confirms the status and importance of Cygnus OB2 as one of our Galaxy's most massive SFRs. This table was created by the HEASARC in October 2009 based on electronic versions of Tables 2, 3 and 4 from the reference paper which were obtained from the CDS (their catalog J/ApJS/184/84 files table2.dat, table3.dat and table4.dat). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/cygob2cxo
- Title:
- Cygnus OB2 Association Chandra X-Ray Point Source Catalog
- Short Name:
- CYGOB2CXO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The aim of this study is to identify the so far unknown low mass stellar population of the ~2 Myr old Cygnus OB2 star forming region, and to investigate the X-ray and near-IR stellar properties of its members. The authors analyzed a 97.7ks Chandra ACIS-I observation pointed at the core of the Cygnus OB2 region. Sources were detected using the PWDETECT code and were positionally correlated with optical and near-IR catalogs from the literature. Source events were extracted with the ACIS EXTRACT package. X-ray variability was characterized through the Kolmogorov-Smirnov test and spectra were fitted using absorbed APEC thermal plasma models. The authors detected 1003 X-ray sources. Of these, 775 have near-IR counterparts and are expected to be almost all associated with Cygnus OB2 members. From near-IR color-color and color-magnitude diagrams, they estimate a typical absorption toward Cygnus OB2 of A<sub>V</sub> ~ 7.0 mag. Although the region is young, very few stars (~ 4.4%) show disk-induced excesses in the near-IR. X-ray variability is detected in ~ 13% of the sources, but this fraction increases, up to 50%, with increasing source statistics. Flares account for at least 60% of the variability. Despite being generally bright, all but 2 of the 26 detected O-type and early B-type stars are not significantly variable. Typical X-ray spectral parameters are log N<sub>H</sub> ~ 22.25 (cm<sup>-2</sup>) and kT ~ 1.35 keV with 1-sigma dispersion of 0.2 dex and 0.4 keV, respectively. Variable and flaring sources have harder spectra with median kT = 3.3 and 3.8 keV, respectively. OB stars are typically softer (kT ~ 0.75 keV). X-ray luminosities range between 10<sup>30</sup> and 10<sup>31</sup> erg s<sup>-1</sup> for intermediate-mass and low-mass stars, and between 2.5 x 10<sup>30</sup> and 6.3 x 10<sup>33</sup> erg s<sup>-1</sup> for OB stars. Cygnus OB2 was observed with the ACIS detector on board the Chandra X-ray Observatory (CXO) on 2004 January 16 (Obs.Id. 4511; PI: E. Flaccomio). The ACIS-I 17' x 17' field of view is covered by 4 chips each with 1024 x 1024 pixels (scale 0.49 arcseconds per pixel). The observation was pointed towards J2000.0 (RA,Dec) = (20 33 12.2, +41 15 00.7). An SNR threshold of 4.5 sigma was chosen which resulted in an initial source list of 1054 sources, 51 of which were subsequently rejected as either instrumental artifacts or multiple detections of the same source with different spatial scales. An additional 10 of the 1003 X-ray sources in the present table are likely spurious statistical fluctuations rather than real sources. This table was created by the HEASARC in March 2008 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/464/211">CDS catalog J/A+A/464/211</a> files table1.dat, table2.dat and table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/cygob2xmm
- Title:
- Cygnus OB2 Association XMM-Newton X-Ray Point Source Catalog
- Short Name:
- CYGOB2XMM
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Cyg OB2 is one of the most massive associations of O-type stars in our Galaxy. Despite the large interstellar reddening towards Cyg OB2, many studies, spanning a wide range of wavelengths, have been conducted to more clearly understand this association. X-ray observations provide a powerful tool to overcome the effect of interstellar absorption and study the most energetic processes associated with the stars in Cyg OB2. The author analyses XMM-Newton data to investigate the X-ray and UV properties of massive O-type stars as well as low-mass pre-main sequence stars in Cyg OB2. Six XMM-Newton observations of the core of Cyg OB2 were obtained. In the analysis, the author paid particular attention to the variability of the X-ray bright OB stars, especially the luminous blue variable candidate Cyg OB2 #12. He found that X-ray variability is quite common among the stars in Cyg OB2. While short-term variations are restricted mostly to low-mass pre-main sequence stars, one third of the OB stars display long-term variations. The X-ray flux of CygO B2 #12 varies by 37%, over timescales from days to years, while its mean log L<sub>X</sub>/L<sub>bol</sub> amounts to -6.10. These properties suggest that Cyg OB2 wind. Two other X-ray bright O-type stars (MT91 516 and CPR2002A11) display variations that suggest they are interacting wind binary systems. This table lists the general properties of the X-ray sources detected in Cyg OB2 with the EPIC cameras onboard XMM-Newton as given in Table 2 of the reference paper. An additional list of the properties of the sources detected inside Cyg OB2 with the two UV filters of the OM instrument onboard XMM-Newton which was contained in Table 4 of the reference paper is not included herein. This table was created by the HEASARC in December 2011 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/536/A31">CDS Catalog J/A+A/536/A31</a> file table2.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/cygtevcxo
- Title:
- Cygnus TeV Source Chandra X-Ray Point Source Catalog
- Short Name:
- CYGTEVCXO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- A 50 ks Chandra observation of the unidentified TeV source in Cygnus reported by the High Energy Gamma-Ray Astronomy (HEGRA) collaboration reveals no obvious diffuse X-ray counterpart. However, 240 pointlike X-ray sources are detected within or nearby the extended TeV J2032+4130 source region, of which at least 36 are massive stars and two may be radio emitters. That the HEGRA source is a composite, having as a counterpart the multiple pointlike X-ray sources that are observed, cannot be ruled out. Indeed, the distribution of pointlike X-ray sources appears nonuniform and concentrated broadly within the extent of the TeV source region. A hypothesis is offered for the origin of the very high energy gamma-ray emission in Cyg OB2 based on the local acceleration of TeV-range cosmic rays and the differential distribution of OB versus less massive stars in this association. The region of TeV J2032+4130 was observed by Chandra on 2004 July 12 for a total effective exposure time of 48,728 seconds using the Advanced CCD Imaging Specrometer imaging array (ACIS-I). The observation was centered on J2000.0 coordinates (RA, Dec) = )20 32 07.0, +41 30 30). This table contains the list of the 240 pointlike sources which were detected in the ACIS-I data and their 2MASS near-IR counterparts, if any are found within 3" of the X-ray sources. 130 (54%) of the 240 X-ray sources have 2MASS counterparts within these error radii. This table was created by the HEASARC in February 2007 based on the electronic version of Table 1 from the above reference which was obtained from the ApJ website. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/xdeep2
- Title:
- DEEP2 Galaxy Redshift Survey Fields Chandra Point Source Catalog
- Short Name:
- XDEEP2
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the X-ray point-source catalog produced from the Chandra Advanced CCD Imaging Spectrometer (ACIS-I) observations of the combined ~3.2 deg<sup>2</sup> DEEP2 (XDEEP2) survey fields, which consist of four ~ 0.7 - 1.1 deg<sup>2</sup> fields. The combined total exposures across all four XDEEP2 fields range from ~ 10 ks to 1.1 Ms. The authors detect X-ray point sources in both the individual ACIS-I observations and the overlapping regions in the merged (stacked) images. They find a total of 2976 unique X-ray sources within the survey area with an expected false-source contamination of ~ 30 sources (<~ 1%). In their paper, the authors present the combined log N-log S distribution of sources detected across the XDEEP2 survey fields and find good agreement with the Extended Chandra Deep Field and Chandra-COSMOS fields to f_(X,0.5-2keV)_ ~ 2 x 10<sup>-16</sup> erg cm<sup>-1</sup> s<sup>-1</sup>. Given the large survey area of XDEEP2, they additionally place relatively strong constraints on the log N-log S distribution at high fluxes (f_(X,0.5-2keV) ~ 3 x 10<sup>-14</sup> erg cm<sup>-1</sup> s<sup>-1</sup>), and find a small systematic offset (a factor ~ 1.5) toward lower source numbers in this regime, when compared to smaller area surveys. The number counts observed in XDEEP2 are in close agreement with those predicted by X-ray background synthesis models. Additionally, the authors present a Bayesian-style method for associating the X-ray sources with optical photometric counterparts in the DEEP2 catalog (complete to R<sub>AB</sub> < 25.2) and find that 2126 (~ 71.4% +/- 2.8%) of the 2976 X-ray sources presented here have a secure optical counterpart with a <~ 6% contamination fraction. The present table provides the DEEP2 optical source properties (e.g., magnitude, redshift) as part of the X-ray-optical counterpart catalog. This table was created by the HEASARC in October 2012 based on electronic versions of Tables 5 and 7 from the reference paper which were obtained from the ApJS web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/sixdfgs
- Title:
- 6dFGS Galaxy Survey Final Redshift Release Catalog
- Short Name:
- SIXDFGS
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The final redshift release of the 6dF Galaxy Survey (6dFGS) is a combined redshift and peculiar velocity survey over the southern sky (|b| > 10 degrees). Its 136,304 spectra have yielded 110,256 new extragalactic redshifts and a new catalogue of 125,071 galaxies making near-complete samples with limits in (K, H, J, r<sub>F</sub>, b<sub>J</sub>) (12.65, 12.95, 13.75, 15.60, 16.75). The median redshift of the survey is 0.053. The catalog includes basic data for the galaxies in the 6dFGS with redshifts, using the best 6dFGS redshifts (radial velocity quality flag Q =3 or 4) plus available redshifts from SDSS, 2dFGRS and ZCAT (124,647 entries in all). It supersedes the previous DR2 version (<a href="https://cdsarc.cds.unistra.fr/ftp/cats/VII/249">CDS Cat. VII/249</a>). The home page of of the 6dFGS database is <a href="http://www-wfau.roe.ac.uk/6dFGS">http://www-wfau.roe.ac.uk/6dFGS</a>. Any use of these data should explicitly state that they come from the Final Release of 6dFGS and cite both the 6dGS DR3 paper (Jones et al. 2009, MNRAS, 399, 683) as well as the original 6dFGS survey paper (Jones et al. 2004, MNRAS, 355, 747). This table was created by the HEASARC in March 2011 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VII/259">CDS Catalog VII/259</a> file 6dfgs.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/twodfqsoz
- Title:
- 2dF QSO Redshift (2QZ) Survey
- Short Name:
- TWODFQSOZ
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The final catalog of the 2dF QSO Redshift Survey (2QZ) is based on Anglo-Australian Telescope 2dF spectroscopic observations of 44,576 color-selected (u, b<sub>J</sub>, r) objects with 18.25 < b<sub>J</sub> < 20.85 selected from automated plate measurement scans of UK Schmidt Telescope (UKST) photographic plates. The 2QZ comprises 23,338 quasi-stellar objects (QSOs), 12,292 galactic stars (including 2,071 white dwarfs) and 4,558 compact narrow emission-line galaxies. The authors obtained a reliable spectroscopic identification for 86 per cent of objects observed with 2dF. They also report on the 6dF QSO Redshift Survey (6QZ), based on UKST 6dF observations of 1,564 brighter (16 < b<sub>J</sub> < 18.25) sources selected from the same photographic input catalog. In total, the authors identified 322 QSOs spectroscopically in the 6QZ. The completed 2QZ is, by more than a factor of 50, the largest homogeneous QSO catalog ever constructed at these faint limits (b<sub>J</sub> < 20.85) and high QSO surface densities (35 QSOs/deg<sup>2</sup>). As such, it represents an important resource in the study of the Universe at moderate-to-high redshifts. The survey area comprised 30 UKST fields, arranged in two 75 degrees by 5 degrees declination strips, one passing across the South Galactic Gap centered on Dec = -30 degrees (the SGP strip), and the other across the North Galactic Gap centered on Dec = 0 degrees (referred to in the reference paper as the equatorial strip, but also known as the NGP strip. The total survey area is 721.6 deg<sup>2</sup>, when allowance is made for regions of sky excised around bright stars. Spectroscopic observations of the input catalogue were made with the 2dF instrument at the Anglo-Australian Telescope (AAT; the 2QZ sample) and the 6dF instrument at the UKST (the 6QZ sample). 2dF spectroscopic observations began in January 1997 and were completed in April 2002. Six-degree Field observations were performed over the period 2001 March-2002 September. This online catalog was created by the HEASARC in October 2010 based on the machine-readable table 2qz.dat obtained from the CDS (their catalog VII/241). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/skyview/nh
- Title:
- Dickey and Lockman HI map
- Short Name:
- nH
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This survey is derived from the 21cm maps presented by Dickey and Lockman in the <i>ARAA</i> 28, p215. The nH is derived assuming optically thin emission. The nH given should be considered a lower limit when the nH is greater than several times 10<sup>20</sup>. Provenance: provided by S. Snowden from data by Dickey and Lockman. This is a service of NASA HEASARC.
- ID:
- ivo://nasa.heasarc/dixon
- Title:
- Dixon Master List of Radio Sources (Version 43)
- Short Name:
- Dixon
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This database table is the Dixon Master List of Radio Sources (Version 43, dated November 1981) which contains flux densities for known radio sources detected at a variety of frequencies. The Master List of Radio Sources was prepared by combining about thirty catalogs of radio sources that were available as of that date into a common format. Notice that this is a list of observations, not of individual sources, and that an entry in this table corresponds to an observation of a radio source at a particular frequency from a particular source catalog: also, no attempt was made by the author to use the same name for the same source, e.g., the source 3C 273 appears more than a dozen times under a variety of names such as PKS 1226+02, NRAO400, CTA 53, etc. This database table was recreated at the HEASARC in June 2005 after it was discovered that the positions had been incorrectly precessed. The original input table used for both the previous and current HEASARC Dixon tables was the 43rd version of the Master List, dated November 1981. It was obtained from the Colorado node of the Astrophysics Data System (ADS), the now-defunct HTTP link <adswww.colorado.edu/catalogs/rad_msl43.html>, and apparently was provided by D. E. Harris on or after 1991. Notice that the version of this table that is currently available at CDS (<a href="https://cdsarc.cds.unistra.fr/ftp/cats/VII/2A">https://cdsarc.cds.unistra.fr/ftp/cats/VII/2A</a>) is, according to Andernach (1989, Bull. Inf. Centre Donnees Stellaires, 37, 139), the 42nd edition (dated 1976) and has only 79493 entries compared to 84510 entries in the HEASARC table. 49 duplicate entries were removed from the HEASARC table in June 2019. This is a service provided by NASA HEASARC .
