- ID:
- ivo://nasa.heasarc/vlalh1400m
- Title:
- VLA Lockman Hole 1400-MHz Radio Source Catalog
- Short Name:
- VLALH1400M
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- In the run-up to routine observations with the upcoming generation of radio facilities, the nature of the sub-mJy radio population has been hotly debated. In this paper, the authors describe multi-frequency data designed to probe the emission mechanism that dominates in these faint radio sources. Their analysis is based on observations of the Lockman Hole (LH) using the Giant Metrewave Radio Telescope (GMRT) near Pune, India - the deepest 610-MHz imaging yet reported - together with 1.4-GHz imaging from the Very Large Array (VLA), which are well matched in resolution and sensitivity to the GMRT data: sigma<sub>610MHz</sub> ~ 15 µJy/beam (µJy/beam), sigma}<sub>1.4GHz</sub> ~ 6 µJy/beam, and full width at half-maximum (FWHM) ~ 5 arcseconds. The GMRT and VLA data are cross-matched to obtain the radio spectral indices for the faint radio emitters. During six 12-hr sessions in 2006 February and July, the authors obtained data at 610 MHz for three pointings (FWHM ~ 43 arcminutes) in the LH (see Table 1 of the reference paper for full details), separated by 11 arcminutes (the LOCKMAN-E, LOCK-3 and LHEX-4 fields), typically with 28 of the 30 antennas that comprise the GMRT. The total integration time in each field, after overheads, was 16 hr. The final image had a noise level in the central 100 arcmin<sup>2</sup> of 14.7 µJy/beam, the deepest map reported at 610 MHz as of the date of publication, despite the modest integration time. New and archival data were obtained at the same three positions using the National Radio Astronomy Observatory's VLA, largely in its B configuration. This table contains 1450 sources found in the LH field at 1400 MHz by the VLA. For 17 of the sources which have multiple components, the 29 individual components are listed as well. Thus, the final table contains 1479 (1450 + 29) entries. Source extraction was based on criteria of peak brightness > 5 times the local rms and integrated flux density > 3 times the local rms. This table was created by the HEASARC in February 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/397/281">CDS Catalog J/MNRAS/397/281</a> file table4.dat. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/vlssr
- Title:
- VLA Low-Frequency Sky Survey Redux Source Catalog
- Short Name:
- VLSSR
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Very Large Array (VLA) Low-Frequency Sky Survey (VLSS: see Cohen et al. 2007, AJ, 134, 1245) covers 95% of the 3 pi sr of sky area above -30 degrees Declination at most RAs (complete above -10 degrees Declination, while in some areas data are available down to Declinations of -36 degrees) at a frequency of 74 MHz, a resolution of 80", and an average rms map sensitivity of sigma ~ 0.130 Jy/beam. The survey was intended to serve as a low-frequency counterpart to the National Radio Astronomy Observatory (NRAO)-VLA Sky Survey (NVSS) at 1400 MHz, allowing spectral information to be compiled for statistical samples of sources. It also provides a low-frequency sky model. In their 2012 and 2014 reference papers, the authors present the details of improvements to data processing and analysis which were used for a re-reduction of the VLSS data, which they dub the VLSS redux or VLSSr. They used the VLSS catalogue as a sky model to correct the ionospheric distortions in the data and create a new set of sky maps and corresponding catalog at 73.8 MHz. The VLSS Redux (VLSSr) has a resolution of 75", and an average map rms noise level of sigma ~ 0.1 Jy beam<sup>-1</sup>. The clean bias is 0.66 x sigma and the theoretical largest angular size is 36 arcminutes. Six previously unimaged fields are included in the VLSSr, which has an unbroken sky coverage over 9.3 steradian above an irregular southern boundary. The final catalog includes 92,965 sources (in the abstract of Lane et al. (2014) it states 92.964 sources). The VLSSr improves upon the original VLSS in a number of areas including imaging of large sources, image sensitivity, and clean bias; however the most critical improvement is the replacement of an inaccurate primary beam correction which caused source flux errors which vary as a function of radius to the nearest pointing center in the VLSS. This table was initially created by the HEASARC in December 2012, based on the FITS file CATALOG.FIT obtained from the NRAO website at <a href="http://www.cv.nrao.edu/vlss/CATALOG/">http://www.cv.nrao.edu/vlss/CATALOG/</a>. It was updated in July 2014 with the the table data from the latest file on the NRAO website (which was marked as last modified on 26 August 2013). Some of the values for the name parameter in the HEASARC's implementation of this table were corrected in April 2018. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/vlam311p4g
- Title:
- VLA M 31 1.4-GHz Source Catalog
- Short Name:
- VLAM311P4G
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the Data Release 2 of the Point Source Catalog created from a series of previously constructed radio-continuum images of M 31 at a wavelength lambda of 20 cm (frequency nu = 1.4 GHz) from archived VLA observations. In total, the authors identify a collection of 916 unique discrete radio sources across the field of M 31. Comparing these detected sources with those listed by Gelfand et al. (2004, ApJS, 155, 89, HEASARC table VLAM31325M) at lambda = 92 cm (325 MHz), the spectral index of 98 sources has been derived. The majority (73%) of these sources exhibit a spectral index of alpha < -0.6, indicating that their emission is predominantly non-thermal in nature, which is typical for background objects and Supernova Remnants (SNRs). This table contains the integrated flux densities for 1,131 detections of 916 unique sources detected at 1.4 GHz in 28 VLA observations. Of these 916 unique sources, 109 were detected in at least two separate images. For such sources, the authors list a group identifier, a group count, and an average flux and error. Sources were cross referenced with the Gelfand et al. (2004) catalog of sources detected at 92 cm. For matched sources, the flux density at this wavelength and the derived spectral index between 20 and 92 cm are listed. This table was created by the HEASARC in May 2015 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/Other/Ser/189.15">CDS Catalog J/Other/Ser/189.15</a> file m31radio.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/vla74mhzdp
- Title:
- VLA 74-MHz Deep High-Resolution Survey Source Catalog
- Short Name:
- VLA74MHZDP
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains some of the results from a 74-MHz survey of a 165 deg<sup>2</sup> region located near the North Galactic Pole (NGP). This survey has an unprecedented combination of both spatial resolution (25" FWHM) and sensitivity (1-sigma as low as 24mJy/beam). The authors detect 949 sources at the 5-sigma level in this region, enough to begin exploring the nature of the 74-MHz source population. In their paper, they present differential source counts, spectral index measurements, and the size distribution as determined from counterparts in the high-resolution FIRST 1.4-GHz survey. They find a trend of steeper spectral indices for the brighter sources. Further, there is a clear correlation between spectral index and median source size, with the flat-spectrum sources being much smaller on average. Ultra-steep spectrum objects (power-law index alpha <= -1.2, where S_nu ~ nu<sup>alpha</sup>) are identified. These sources are excellent candidates for high-redshift radio galaxies. The data used to produce this survey come from observations taken on 1998 March 7 intended to map two normal galaxies at 74 MHz (NGC 4565 and NGC 4631). These two pointings were separated by 6.4 degrees, roughly the radius of the primary beam at 74 MHz, allowing them to be ideally combined to produce a single deep image roughly 17 x 10 degrees in size. The combination of VLA A-configuration resolution (25 arcsec), favorable ionospheric conditions, and pointings in directions near the NGP, where the background temperature is low, produced the deepest observation ever obtained below 100 MHz. The same algorithm that was used in the 1.4-GHz NVSS was used to identify and characterize sources in this 74-MHz survey. The source detection algorithm had a threshold such that sources must have both a peak and integrated flux density level of at least 5 times the local rms noise level. Since the rms noise level varied from 24 mJy/beam to 80 mJy mJy/beam at the chosen field edge, the absolute level of the source-detection threshold of 5-sigma likewise varied over the image. This table was created by the HEASARC in August 2010 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/150/417/">CDS catalog J/ApJS/150/417/</a> file table2.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/vlam31325m
- Title:
- VLA M 31 325-MHz Source Catalog
- Short Name:
- VLAM31325M
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains some of the results from a 325-MHz radio survey of M 31, conducted with the A configuration of the Very Large Array. The survey covered an area of 7.6 square degrees, and a total of 405 radio sources between <~ 6" and 170" in extent were mapped with a resolution of 6" and a 1-sigma sensitivity of ~ 0.6mJy/beam. For each source, its morphological class, major axis theta<sub>M</sub>, minor axis theta<sub>m</sub>, position angle theta<sub>PA</sub>, peak flux I, integrated flux density S, spectral index alpha, and spectral curvature parameter {phi were calculated. A comparison of the flux and radial distribution - both in the plane of the sky and in the plane of M 31 - of these sources with those of the XMM-Newton Large-Scale Structure Survey and the Westerbork Northern Sky Survey revealed that a vast majority of sources detected are background radio galaxies. As a result of this analysis, the authors expect that only a few sources are intrinsic to M 31. This study is based on a 5 hr (4 hr on-source) observation of M 31 conducted on 2000 December 15 with the VLA in A configuration. The procedures used to generate the source list and the source properties (essentially making use of the MIRIAD task SFIND) are discussed in Sections 2.2.2 and 2.3 of the reference paper, respectively. This table was created by the HEASARC in September 2014 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/155/89">CDS Catalog J/ApJS/155/89</a> file table3.dat, the GLG (Gelfand, Lazio, Gaensler) source list. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/vlaonccat
- Title:
- VLA Orion Nebula Cluster Compact Source Catalog
- Short Name:
- VLAONCCAT
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a deep centimeter-wavelength catalog of the Orion Nebula Cluster (ONC), based on a 30-hr single-pointing observation with the Karl G. Jansky Very Large Array (JVLA) in its high-resolution A configuration using two 1-GHz bands centered on 4.7 and 7.3 GHz. A total of 556 compact sources were detected in a map with a nominal rms noise of 3 µJy/beam, limited by complex source structure and the primary beam response. Compared to previous catalogs, these detections increase the sample of known compact radio sources in the ONC by more than a factor of seven. The new data show complex emission on a wide range of spatial scales. Following a preliminary correction for the wideband primary-beam response, the authors determine radio spectral indices for 170 sources whose index uncertainties are less than +/-0.5. They compare the radio to the X-ray and near-infrared point-source populations, noting similarities and differences. The observations were carried out with the JVLA of the National Radio Astronomy Observatory on 2012 September 30 and October 2-5 under the auspices of the project code SD630. Data were taken using the VLA's C-band (4-8 GHz) receivers in full polarization mode, with two 1-GHz basebands centered at 4.736 and 7.336 GHz to provide a good baseline for source spectral index determination. Apart from the first epoch, the field was simultaneously observed with the Chandra X-Ray Observatory. Mostly of interest for variability information, these data will be presented as part of a follow-up paper. This table was created by the HEASARC in September 2016 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/822/93">CDS Catalog J/ApJ/822/93</a> file table1.dat (the compact source catalog). Some of the values for the name parameter in the HEASARC's implementation of this table were corrected in April 2018. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/vlass821p4
- Title:
- VLA SDSS Stripe 82 Survey 1.4-GHz Source Catalog
- Short Name:
- VLASS821P4
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains results from a high-resolution radio survey of the Sloan Digital Sky Survey (SDSS) Southern Equatorial Stripe, also known as Stripe 82. This 1.4-GHz survey was conducted with the Very Large Array (VLA) primarily in the A configuration, with supplemental B configuration data to increase sensitivity to extended structure. The survey has an angular resolution of 1.8 arcseconds and achieves a median rms noise of 52 µJy/beam (µJy/beam) over 92 deg<sup>2</sup>. This is the deepest 1.4-GHz survey to achieve this large of an area, filling a gap in the phase space between small, deep and large, shallow surveys. It also serves as a pilot project for a larger high-resolution survey with the Expanded Very Large Array (EVLA). The authors discuss the technical design of the survey and details of the observations, and outline their method for data reduction, in the reference paper. They present a catalog of 17,969 isolated radio components, for an overall source density of ~195 sources deg<sup>-2</sup>. The astrometric accuracy of the data is excellent, with an internal check utilizing multiply observed sources yielding an rms scatter of 0.19 arcseconds in both Right Ascension and Declination. A comparison to the SDSS DR7 Quasar Catalog further confirms that the astrometry is well-tied to the optical reference frame, with mean offsets of 0.02" +/- 0.01" in Right Ascension, and 0.01" +/- 0.02" in Declination. A check of their photometry reveals a small, negative CLEAN-like bias on the level of 35 uJy. The authors report on the catalog completeness, finding that 97% of FIRST-detected quasars are recovered in the new Stripe 82 radio catalog, while faint, extended sources are more likely to be resolved out by the resolution bias. In their paper, they conclude with a discussion of the optical counterparts to the catalog sources, including 76 newly detected radio quasars. The full catalog as well as a search page and cutout server are available online at <a href="http://third.ucllnl.org/cgi-bin/stripe82cutout">http://third.ucllnl.org/cgi-bin/stripe82cutout</a>. The SDSS Stripe 82 observations were made with the National Radio Astronomy Observatory's (NRAO's) VLA. The data were collected over two VLA cycles, 2007-2008 and 2008-2009. The majority of the observations were taken in the A configuration, but the authors also obtained B-configuration coverage of the area in order to improve the sampling of the Fourier (U-V) plane and to increase sensitivity to the extended structure. Area 1 (delineated in black in Figure 1(a) of the paper) was covered in the A and B configurations in 2007-2008, and Area 2 (delineated in purple in Figure 1(a) of the paper) in the A and B configurations in 2008-2009. Area 1 is made up of 275 pointings, and Area 2 has 374, coming to 649 fields, and 92 deg<sup>2</sup> covered in total. This table was created by the HEASARC in August 2013 based on a complete machine-readable version of Table 1 from the reference paper which was kindly provided by the first author. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/vlasxdf1p4
- Title:
- VLA Subaru/XMM-Newton Deep Field 1.4-GHz Source Catalog
- Short Name:
- VLASXDF1P4
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains results from the deep radio imaging at 1.4 GHz of the 1.3-deg<sup>2</sup> Subaru/XMM-Newton Deep Field (SXDF), made with the Very Large Array (VLA) in B and C configurations. This resulted in a radio map of the entire field, and a catalog of 505 sources covering 0.8 deg<sup>2</sup> to a peak flux density limit of 100 microJansky (µJy), which corresponds to signal-to-noise (S/N) ratios of between 5 and 8. Robust optical identifications are provided for 90 per cent of the sources, and suggested identifications are presented for all but 14 (of which seven are optically blank, and seven are close to bright contaminating objects). The authors show that the optical properties of the radio sources do not change with flux density, suggesting that active galactic nuclei (AGN) continue to contribute significantly at faint flux densities. they test this assertion by cross-correlating their radio catalog with the X-ray source catalog and conclude that radio-quiet AGN become a significant population at flux densities below 300 uJy, and may dominate the population responsible for the flattening of the radio source counts if a significant fraction of them are Compton-thick. The SXDF was observed with NRAO's VLA in B-array using the 14 overlapping pointings arranged an an hexagonal pattern that are listed in Table 1 of the reference paper. Three test observations of pointings 1, 4 and 6 were taken on 2001 May 17, and the rest of the data were obtained in 13 runs, each lasting 4.5 hours, between 2002 August 10 and September 9. All 14 pointings were re-observed in C-array on 2003 January 15 to provide additional information on larger angular scales. This table contains the catalog of 505 detected radio sources and their proposed optical counterparts (the latter taken mostly from the ultra-deep BRíz' Suprime-Cam images of the SXDF). As mentioned above, 14 of these 505 radio sources have no suggested identifications. Additionally, 7 of the radio sources (source numbers 16, 114, 129, 263, 360, 361 and 488) have 2 listed optical identifications: in such cases, there are 2 entries for each source listed detailing the alternative optical counterparts, and with identical sets of radio parameters. Thus, there are 512 = 505 + 7 entries in this table. This table was created by the HEASARC in August 2013 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/372/741">CDS Catalog J/MNRAS/372/741</a> file table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/vlasxdfoid
- Title:
- VLA Subaru/XMM-Newton Deep Field 1.4-GHz Sources Optical/Near-IR Counterparts
- Short Name:
- VLASXDFOID
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- In Simpson et al. (2006, MNRAS, 372, 741, hereafter Paper I, available at the HEASARC as the <a href="/W3Browse/radio-catalog/vlasxdf1p4.html">VLASXDF1P4</a> table, the authors presented a catalog of 505 sources with 1.4-GHz peak radio flux densities greater than 100 uJy over a 0.81 deg<sup>2</sup> region of the Subaru/XMM-Newton Deep Field (SXDF) and some of the properties of their optical counterparts. In this study (Simpson et al. 2012, MNRAS, 421, 3060, Paper III in the series) the authors present spectroscopic and 11-band photometric redshifts for galaxies in the 100-uJy Subaru/XMM-Newton Deep Field radio source sample. The authors find good agreement between their redshift distribution and that predicted by the Square Kilometre Array (SKA) Simulated Skies project. They find no correlation between K-band magnitude and radio flux, but show that sources with 1.4-GHz flux densities below ~ 1 mJy are fainter in the near-infrared than brighter radio sources at the same redshift, and they discuss in their paper the implications of this result for spectroscopically incomplete samples where the K-z relation has been used to estimate redshifts. The authors use the infrared-radio correlation to separate their sample into radio-loud and radio-quiet objects and show that only radio-loud hosts have spectral energy distributions consistent with predominantly old stellar populations, although the fraction of objects displaying such properties is a decreasing function of radio luminosity. Many of the spectra presented in this study were obtained as part of the European Southern Observatory (ESO) program P074.A-0333, undertaken using the Visible Multi-Object Spectrograph (VIMOS) instrument on UT3/Melipal. Several observational campaigns have obtained spectra of objects within the SXDF, and Paper II in this series (Vardoulaki et al. 2008, MNRAS, 387, 505) presented spectra for 28 of the brightest 37 radio sources, obtained from a variety of sources. The near-infrared data used here come from the third data release (DR3) of the UKIRT (United Kingdom Infrared telescope) Infrared Deep Sky Survey, while the optical data in the UDS come from the SXDF, which comprises five separate Suprime-Cam pointings. This table was created by the HEASARC in August 2013 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/421/3060">CDS Catalog J/MNRAS/421/3060</a> file table1.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/vlacdfscat
- Title:
- VLA Survey of Chandra Deep Field South
- Short Name:
- VLACDFSCAT
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains some of the results from 20 and 6 cm VLA deep observations of the Chandra Deep Field-South (CDF-S), including the Extended CDF-S (E-CDF-S). In the reference paper, the authors discuss the radio properties of 266 cataloged radio sources, of which 198 are above a 20-cm completeness level reaching down to 43 microJanskies (µJy) at the center of the field. Survey observations made at 6 cm over a more limited region cover the original CDF-S to a comparable level of sensitivity as the 20-cm observations. Of 266 cataloged radio sources, 52 have X-ray counterparts in the CDF-S and a further 37 have counterparts in the E-CDF-S area not covered by the 1 Ms exposure. Using a wide range of material, the authors have found optical or infrared counterparts for 254 radio sources, of which 186 have either spectroscopic or photometric redshifts. Three radio sources have no apparent counterpart at any other wavelength. Measurements of the 20-cm radio flux density at the position of each CDF-S X-ray source detected a further 30 radio sources (not included in this table) above a conservative 3-sigma detection limit. X-ray and sub-millimeter observations have been traditionally used as a measure of AGN and star formation activity, respectively. These new observations probe the faint end of both the star formation and radio galaxy/AGN population, as well as the connection between the formation and evolution of stars and SMBHs. Both of the corresponding gravitational and nuclear fusion-driven energy sources can lead to radio synchrotron emission. AGN and radio galaxies dominate at high flux densities. Although emission from star formation becomes more prominent at the microJansky levels reached by deep radio surveys, even for the weakest sources, an apparent significant contribution from low-luminosity AGN as well as from star formation is still found. Notice that are 319 entries in this table corresponding to the 266 catalogued radio sources, due to the fact that some of these sources have multiple components. In such cases, the composite source as well as each of its components are listed as separate entries, e.g., source 7 which has 3 components (A, B and C) has 4 entries in this table. This table was created by the HEASARC in November 2008 based on the electronic version of Table 1 from the reference paper which was obtained from the ApJ web site. This is a service provided by NASA HEASARC .
