- ID:
- ivo://nasa.heasarc/vlaecdfsoi
- Title:
- VLA Extended-Chandra Deep Field-South 1.4-GHz Sources Opt/IR Counterparts
- Short Name:
- VLAECDFSOI
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a sample of 883 sources detected in a deep Very Large Array (VLA) survey at 1.4 GHz in the Extended-Chandra Deep Field South (E-CDFS). The reference paper focuses on the identification of their optical and infrared (IR) counterparts. The authors use a likelihood-ratio technique that is particularly useful when dealing with deep optical images to minimize the number of spurious associations. They find a reliable counterpart for 95% of their radio sources. Most of the counterparts (74%) are detected at optical wavelengths, but there is a significant fraction (21%) that are only detectable in the IR. Combining newly acquired optical spectra with data from the literature, the authors are able to assign a redshift to 81% of the identified radio sources (37% spectroscopic). They also investigate the X-ray properties of the radio sources using the Chandra 4 Ms and 250 ks observations. In particular, the authors use a stacking technique to derive the average properties of radio objects undetected in the Chandra images. The results of their analysis are collected in this new catalog containing the position of the optical/IR counterpart, the redshift information, and the X-ray fluxes. It is the deepest multi-wavelength catalog of radio sources, which will be used for future study of this galaxy population. The E-CDFS was observed at 1.4 GHz with the VLA between 2007 June and September (Miller et al. 2008, ApJS, 179, 114). The mosaic image covered an area of about 34 by 34 arcminutes with near-uniform sensitivity. The typical rms is 7.4 µJy for a 2.8 by 1.6 arcseconds beam. The second data release (N. Miller et al. 2012, in preparation) provides a new source catalog with a 5-sigma point-source detection limit, for a total of 883 sources. The median value of the distribution is 58.5 µJy and the median signal-to-noise ratio (S/N) is 7.6. The authors note that ~ 90% of the sample has a flux density below 1 mJy, a regime where radio-quiet AGNs and star-forming galaxies (SFGs) become the dominant populations This table was created by the HEASARC in November 2012 based on the files table3.dat and table5.dat which were obtained from the ApJS web site. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/vlanep
- Title:
- VLA 1.5-GHz North Ecliptic Pole Survey
- Short Name:
- VLA
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The VLANEP database contains the VLA-NEP survey of 29.3 square degrees around the North Ecliptic Pole mapped with the VLA at 20 cm (1.5 GHz) in the `C-configuration`. The database table contains 2435 radio sources with flux densities ranging from 0.3 to 1000 mJy, including over 200 fainter than 1 mJy. Source positions have been corrected for instrumental effects, and most positions are accurate to less than 2 arcseconds. The sensitivity varies from field to field, with the 1 sigma level being approximately 0.06 mJy at the center of the inner fields and 0.12 mJy at the center of the outer fields. Sensitivity drops with distance from the center of each field due to the primary beam response of the VLA antennas and interferometer effects. Source flux densities have been corrected for these effects. The spatial resolution varies from field to field, with the typical HPBW being 20 arcseconds. Source positions have been corrected for instrumental effects, and most positions are accurate to less than 2 arcseconds. Approximately 6% of the sources were found to be extended with angular sizes greater than 30 arcseconds. This catalog was recreated at the HEASARC in February 2001 (replacing a previous version: some parameters were renamed, and the source names were changed to the format recommended for VLA-NEP sources in the Dictionary of Nomenclature of Celestial Objects maintained at the CDS) based on CDS/ADC Catalog J/ApJS/93/145/table2. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/lowzvlqvla
- Title:
- VLA 6-GHz Observations of Low-Redshift SDSS QSOs
- Short Name:
- LOWZVLQVLA
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains results from 6-GHz Jansky Very Large Array (JVLA) observations covering a volume-limited sample of 178 low-redshift (0.2 < z <0.3) optically selected quasi-stellar objects (QSOs). These 176 radio detections fall into two clear categories: (1) about 20% are radio-loud QSOs (RLQs) with spectral luminosities of L<sub>6</sub> >~ 10<sup>23.2</sup> W/Hz that are primarily generated in the active galactic nucleus (AGN) responsible for the excess optical luminosity that defines a bona fide QSO; and (2) the remaining 80% that are radio-quiet QSOs (RQQs) that have 10<sup>21</sup> <~ L<sub>6</sub> <~ 10<sup>23.2</sup> W/Hz and radio sizes <~ 10 kpc, and the authors suggest that the bulk of their radio emission is powered by star formation in their host galaxies. "Radio-silent" QSOs (L_6_<~ 10<sup>21</sup> W/Hz) are rare, so most RQQ host galaxies form stars faster than the Milky Way; they are not "red and dead" ellipticals. Earlier radio observations did not have the luminosity sensitivity of L<sub>6</sub> <~ 10<sup>21</sup> W/Hz that is needed to distinguish between such RLQs and RQQs. Strong, generally double-sided radio emission spanning >> 10 kpc was found to be associated with 13 of the 18 RLQ cores with peak flux densities of S<sub>p</sub> > 5 mJy/beam (log(L) >~ 24). The radio luminosity function of optically selected QSOs and the extended radio emission associated with RLQs are both inconsistent with simple "unified" models that invoke relativistic beaming from randomly oriented QSOs to explain the difference between RLQs and RQQs. Some intrinsic property of the AGN or their host galaxies must also determine whether or not a QSO appears radio-loud. The authors have reprocessed the VLA observations of a sample of SDSS QSOs discussed in Kimball et al. (2011, ApJ, 739, L29). These were obtained using the VLA C configuration with a central frequency of 6 GHz and a bandwidth of 2 GHz in each of the two circular polarizations: with natural weighting the synthesized beam width was 3.5 arcseconds FWHM. The authors generated a catalog of radio sources associated with each QSO. They detected radio emission at 6 GHz from all but two of the 178 color-selected SDSS QSOs contained in this volume-limited sample of QSOs more luminous than M<sub>i</sub> = -23 and with redshifts 0.2 < z < 0.3. All calculations in the reference paper assume a flat LambdaCDM cosmology with H<sub>0</sub> = 70 km s<sup>-1</sup> Mpc<sup>-1</sup> and Omega<sub>Lambda</sub> = 0.7. Spectral luminosities are specified by their source-frame frequencies, flux densities are specified in the observer's frame, and a mean spectral index of alpha = d(log S)/d(log nu) = -0.7 is used to make frequency conversions This table was created by the HEASARC in April 2017 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/831/168">CDS Catalog J/ApJ/831/168</a> file table1.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/vlagoodsn
- Title:
- VLA GOODS-North Field 1.4-GHz Source Catalog
- Short Name:
- VLAGOODSN
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains results from deep, new, wide-field radio continuum observations of the Great Observatories Origins Deep Survey-North (GOODS-North) field. (The GOODS-North field covers ~160 arcmin<sup>2</sup> centered on the Hubble Deep Field North (Williams et al. 1996, AJ, 112, 1335) and is unrivaled in terms of its ancillary data sets, which include extremely deep Chandra, Hubble Space Telescope (HST), and Spitzer observations, deep UBVRIJHK ground-based imaging and ~3500 spectroscopic redshifts from 8 to 10 m telescopes). The resulting 1.4-GHz map has a synthesized beam size of ~1.7" and an rms noise level of ~3.9 microJansky per beam (µJy/beam) near its center and ~8 µJy/beam at 15 arcminutes from phase center. The authors have cataloged 1230 discrete radio emitters, within a 40' x 40' region, above a 5-sigma detection threshold of ~20 uJy at the field center. New techniques, pioneered by Owen & Morrison (2008, AJ, 136, 1889), have enabled the authors to achieve a dynamic range of 6800:1 in a field that has significantly strong confusing sources. The authors compare the 1.4-GHz (20-cm) source counts with those from other published radio surveys. Their differential counts are nearly Euclidean below 100 uJy with a median source diameter of ~1.2". This adds to the evidence presented by Owen & Morrison that the natural confusion limit may lie near 1 uJy. If the Euclidean slope of the counts continues down to the natural confusion limit as an extrapolation of their log N-log S, this indicates that the cutoff must be fairly sharp below 1 uJy, else the cosmic microwave background temperature would increase above 2.7K at 1.4GHz. A useful combined total of 165 hours of NRAOS's Very Large Array (VLA) A-configuration 1.4-GHz observations were obtained between 2005 February and 2006 February, all done at night so as to avoid solar interference, for a region centered at RA and Dec of 12:36:49.4, +62:12:58 (J2000). (See Table 1 of the reference paper for the VLA observing log) This table was created by the HEASARC in September 2013 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/188/178">CDS Catalog J/ApJS/188/178</a> file table2.dat This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/vlagbsper
- Title:
- VLA Goulds Belt Survey Perseus Region Source Catalog
- Short Name:
- VLAGBSPER
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a source catalog from multi-epoch, large-scale (~2,000 arcmin<sup>2</sup>), fairly deep (~16 microJansky or uJy), high-resolution (~1") radio observations of the Perseus star-forming complex that were obtained with the Karl G. Jansky Very Large Array (VLA) at frequencies of 4.5 and 7.5 GHz. These observations were mainly focused on the clouds NGC 1333 and IC 348, although the authors also observed several fields in other parts of the Perseus complex. They detect a total of 206 sources, 42 of which are associated with young stellar objects (YSOs). The radio properties of about 60% of the YSOs are compatible with a non-thermal radio emission origin. Based on their sample, the authors find a fairly clear relation between the prevalence of non-thermal radio emission and the evolutionary status of the YSOs. By comparing their results with previously reported X-ray observations, they show that YSOs in Perseus follow a Gudel-Benz relation with a value of the kappa parameter (L<sub>X</sub>/L<sub>rad</sub> = kappa x 10<sup>(15.5 +/- 1)</sup> [Hz]) of 0.03, consistent with other regions of star formation. The authors argue that most of the sources detected in their observations that are not associated with known YSOs are extragalactic, but provide a list in the reference paper Of 20 unidentified radio sources whose radio properties are consistent with them being YSO candidates. Finally, they also detect five sources with extended emission features that can clearly be associated with radio galaxies. The observations were collected with the VLA of the National Radio Astronomy Observatory in B and BnA configurations. Two frequency sub-bands, each 1 GHz wide and centered at 4.5 and 7.5 GHz, respectively, were recorded simultaneously. The observations were obtained in three observing sessions, on 2011 March 06/13, April 14/25, and May 01/02/10/19/22, typically separated from one another by a month. This dual-frequency, multi-epoch strategy was chosen to enable the characterization of the spectral index and variability of the detected sources, as well as to help with the identification of the emission mechanisms. The locations of the VLA observations are shown in Figure 1 of the reference paper. Other details of the observations are given in Table 1 of the reference paper. The approximate positions of the two main fields observed are: <pre> RA (ICRS) DE Designation(s) </pre> 03 28 55 +31 22.2 Ced 16 = NGC 1333 03 44 34 +32 09.8 NAME omi Per Cloud = IC 348 <pre> This HEASARC table contains the contents of Table 2 (74 radio sources detected in NGC 1333), Table 3 (91 radio sources detected in IC 348) and Table 4 (41 radio sources detected in single fields in Perseus) from the reference paper, totaling 206 radio sources. This table was created by the HEASARC in February 2018 based on an ASCII version of Table 2 from the reference paper that was obtained from the ApJ website and on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/818/116">CDS catalog J/ApJ/818/116</a> files table3.dat and table4.dat that contains Tables 3 and 4 from the reference paper. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/vlahdf20cm
- Title:
- VLA Hubble Deep Field 20-cm Source Catalog
- Short Name:
- VLAHDF20CM
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors have conducted a deep radio survey with the Very Large Array (VLA) at 1.4 GHz of a region containing the Hubble Deep Field (HDF). This survey overlaps previous observations at 8.5 GHz allowing them to investigate the radio spectral properties of microJansky sources to flux densities greater than 40 µJy (µJy) at 1.4 GHz and greater than 8 uJy at 8.5 GHz. A total of 371 sources have been catalogued at 1.4 GHz as part of a complete sample within 20 arcminutes of the HDF. The differential source count for this region is only marginally sub-Euclidean and is given by n(S) = (8.3 +/- 0.4) S^(-2.4 +/- 0.1) sr<sup>-1</sup> Jy<sup>-1</sup>. Above about 100 uJy the radio source count is systematically lower in the HDF as compared to other fields. The authors conclude that there is clustering in this radio sample on size scales of 1 to 40 arcminutes. The 1.4 GHz-selected sample shows that the radio spectral indices are preferentially steep (mean spectral index of 0.85) and that the sources are moderately extended with average angular size Theta = 1.8". Optical identification with disk-type systems at z ~ 0.1 - 1 suggests that synchrotron emission, produced by supernovae remnants, is powering the radio emission in the majority of sources. In 1996 November, the authors observed a field centered on the Hubble Deep Field (RA, Dec (J2000.0) = (12<sup>h</sup> 36<sup>m</sup> 49.4<sup>s</sup>, 62<sup>o</sup> 12' 58.00") for a total of 50 hours at 20 cm in the A configuration of the VLA. They reached an rms noise level near the center of the field of 7.5 uJy. They adopted 40 uJy as the formal completeness limit over the entire 1 degree field in their untapered naturally weighted 2 arcseconds image. The authors identified 314 sources within 20 arcminutes of the field center (20% power contour). They found 57 additional sources within this same region (presumably resolved at 2" resolution) in lower resolution (3.5 and 6") tapered images above completeness levels of 50 uJy at 3.5" resolution and 75 uJy at 6" resolution, making a grand total of 371 radio sources detected at 1.4 GHz within 20 arcminutes of the phase center of the field. This table was created by the HEASARC in June 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/533/611">CDS Catalog J/ApJ/533/611</a> file table2.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/vlalhn3ghz
- Title:
- VLA Lockman Hole 3-GHz Radio Source Catalog
- Short Name:
- VLALHN3GHZ
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table is from the second of two papers describing the observations and source catalogs derived from sensitive 3-GHz images of the Lockman Hole North using the Karl G. Jansky Very Large Array (VLA). In their paper, the authors describe the reduction and cataloguing process, which yielded an image with 8-arcsecond resolution and instrumental noise of sigma<sub>n</sub> = 1.01 µJy/beam (µJy/beam) rms (before primary beam corrections) and a catalog of 558 sources detected above 5 * sigma<sub>n</sub>. The authors also include details of how they estimate source spectral indices across the 2-GHz VLA bandwidth, finding a median index of -0.76 +/- 0.04. Stacking of source spectra reveals a flattening of spectral index with decreasing flux density. In the reference paper, the authors present a source count derived from the catalog. They show a traditional count estimate compared with a completely independent estimate made via a P(D) confusion analysis, and find very good agreement. Cross-matches of the catalog with X-ray, optical, infrared, radio, and redshift catalogs are also presented. The X-ray, optical and infrared data, as well as AGN selection criteria allow them to classify 10% as radio-loud AGN, 28% as radio-quiet AGN, and 58% as star-forming galaxies, with only 4% unclassified. Observations were made with the VLA in the C configuration at S band, with a frequency range of 2 to 4GHz, with a total of roughly 50 hours of on-source time in 2012. The HEASARC has converted the radio and IR flux density units from those given in the original table (µJy and µJy/beam) to its standard units for radio flux densities (mJy and mJy/beam). This table was created by the HEASARC in April 2017 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/462/2934">CDS Catalog J/MNRAS/462/2934</a> files cat3ghz.dat and catcrx.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/vlalh1400m
- Title:
- VLA Lockman Hole 1400-MHz Radio Source Catalog
- Short Name:
- VLALH1400M
- Date:
- 02 May 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 .
- ID:
- ivo://nasa.heasarc/vlssr
- Title:
- VLA Low-Frequency Sky Survey Redux Source Catalog
- Short Name:
- VLSSR
- Date:
- 02 May 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:
- 02 May 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 .
