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981. VLA ELAIS N1, N2, N3 Fields 20-cm Source Catalog
ID:
ivo://nasa.heasarc/vlaen20cm
Title:
VLA ELAIS N1, N2, N3 Fields 20-cm Source Catalog
Short Name:
VLAEN20CM
Date:
07 Mar 2025
Publisher:
NASA/GSFC HEASARC
Description:
The authors have used the Very Large Array (VLA) in C configuration to carry out a sensitive 20-cm radio survey of regions of the sky that have been surveyed in the far-infrared (FIR) over the wavelength range 5 -200 microns (µm) with ISO (Infrared Space Observatory) as part of the European Large-Area ISO Survey (ELAIS). As usual in surveys based on a relatively small number of overlapping VLA pointings, the flux limit varies over the area surveyed: from a 5-sigma limit of 0.135 mJy over an area of 0.12 deg<sup>2</sup> to 1.15 mJy or better over the whole region covered of 4.22 deg<sup>2</sup>. In their paper, the authors present the complete radio catalog of 867 sources, 428 of which form a complete sample in the flux range 0.2 - 1.0 mJy. These regions of the sky have previously been surveyed to shallower flux limits at 20 cm with the VLA as part of the VLA D-configuration NVSS (full width at half-maximum, FWHM = 45arcseconds) and VLA-B configuration FIRST (FWHM = 5 arcseconds) surveys. This whole survey has a nominal 5-sigma flux limit a factor of 2 below that of the NVSS; 3.4 deg<sup>2</sup> of the survey reaches the nominal flux limit of the FIRST survey and 1.5 deg<sup>2</sup> reaches 0.25 mJy, a factor of 4 below the nominal FIRST survey limit. In addition, this survey is at a resolution intermediate between the two surveys and thus is well suited for a comparison of the reliability and resolution-dependent surface brightness effects that affect interferometric radio surveys. The authors have carried out a detailed comparison of their survey and these two independent surveys in order to assess the reliability and completeness of each. Considering the whole sample, they found that to the 5-sigma nominal limits of 2.3 and 1.0 mJy, respectively, the NVSS and FIRST surveys have a completeness of 96<sup>+2</sup><sub>-3</sub> and 89<sup>+2</sup><sub>-3</sub> % and a reliability of 99<sup>+1</sup><sub>-2</sub> and 94<sup>+2</sup><sub>-2</sub> %. The radio observations were obtained of three ISO ELAIS survey regions in the Northern celestial hemisphere (N1 1610+5430, N2 1636+4115 and N3 1429+3306) (see Table 1 of the reference paper for the details of the fields and the individual pointings). The observations are made with the Very Large Array (VLA) radio telescope at 1.4 GHz (20 cm) in the VLA C configuration (maximum baseline 3.4 km) with an angular resolution (FWHM) of ~15 arcseconds. The aim of these VLA observations was to obtain uniform coverage of the ELAIS regions with an rms noise limit of ~50 microJansky (µJy). This table contains the 921 components of 867 total sources detected at a level of >= 5 sigma (44 of which are multiple component sources as defined in Section 4.3 of the reference paper) over a total area of 4.222 deg<sup>2</sup>. There are also entries describing the properties of the total sources for the 44 multi-component sources (for which the positions have been computed as the flux-weighted average positions of their components), and thus this catalog contains 965 (921 + 44) entries. To filter out the latter, component_id values != 'T' should be selected when searching this table. This table was originally ingested by the HEASARC in August 2012, based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/302/222">CDS Catalog J/MNRAS/302/222</a> file table3.dat. It was last updated in September 2013 to remove a duplicate entry for the source ELAISR J142743+331323. This is a service provided by NASA HEASARC .
982. VLA Extended-Chandra Deep Field-South Classification Catalog
ID:
ivo://nasa.heasarc/vlaecdfscls
Title:
VLA Extended-Chandra Deep Field-South Classification Catalog
Short Name:
VLAECDFSCLS
Date:
07 Mar 2025
Publisher:
NASA/GSFC HEASARC
Description:
The sub-mJy radio population is a mixture of active systems, that is star-forming galaxies (SFGs) and active galactic nuclei (AGNs). In their paper, the authors study a sample of 883 radio sources detected at 1.4 GHz in a deep Very Large Array (VLA) survey of the Extended Chandra Deep Field-South (E-CDF-S) that reaches a best rms sensitivity of 6 microJansky (µJy). The authors have used a simple scheme to disentangle SFGs, radio-quiet (RQ), and radio-loud (RL) AGNs based on the combination of radio data with Chandra X-ray data and mid-infrared observations from Spitzer. They find that at flux densities between about 30 and 100 uJy, the radio population is dominated by SFGs (~60%) and that RQ AGNs become increasingly important over RL ones below 100 uJy. In the paper, the authors also compare the host galaxy properties of the three classes in terms of morphology, optical colors and stellar masses. Their results show that both SFG and RQ AGN host galaxies have blue colors and late-type morphology while RL AGNs tend to be hosted by massive red galaxies with early-type morphology. This supports the hypothesis that radio emission in SFGs and RQ AGNs mainly comes from the same physical process: star formation in the host galaxy. This table was created by the HEASARC in January 2014 based on the machine-readable version of Table 1 from the reference paper which was obtained from the MNRAS web site. This is a service provided by NASA HEASARC .
983. VLA Extended-Chandra Deep Field-South 1.4-GHz Source Catalog
ID:
ivo://nasa.heasarc/vlaecdfs1p4
Title:
VLA Extended-Chandra Deep Field-South 1.4-GHz Source Catalog
Short Name:
VLAECDFS1P4
Date:
07 Mar 2025
Publisher:
NASA/GSFC HEASARC
Description:
Deep radio observations at 1.4 GHz for the Extended Chandra Deep Field South were performed in 2007 June through September and presented in a first data release (Miller et al. 2008, ApJS, 179, 114). The survey was made using six separate pointings of the Very Large Array with over 40 hr of observation per pointing. In the current study, the authors improve on the data reduction to produce a second data release (DR2) mosaic image. This DR2 image covers an area of about a third of a square degree, reaches a best rms sensitivity of 6 µJy (µJy), and has a typical sensitivity of 7.4 uJy per 2.8" by 1.6" beam. The authors also present a more comprehensive catalog, including sources down to peak flux densities of five or more times the local rms noise, along with information on source sizes and relevant pointing data. In their paper, they discuss in some detail the consideration of whether sources are resolved under the complication of a radio image created as a mosaic of separate pointings, each suffering some degree of bandwidth smearing, and the accurate evaluation of the flux densities of such sources. Finally, the radio morphologies and optical/near-IR counterpart identifications are used to identify 17 likely multiple-component sources so as to arrive at a catalog of 883 radio sources (and also 49 individual components of the 17 multi-component sources), which is roughly double the number of sources contained in the first data release. In order to cover the full E-CDF-S area at near-uniform sensitivity, the authors pointed the VLA at six separate coordinate locations arranged in a hexagonal grid around the adopted center of the CDF-S, viz. RA, Dec (J2000) 03<sup>h</sup> 32<sup>m</sup> 28.00<sup>s</sup>, -27<sup>o</sup> 48' 30.0". The observations were spread over many days on account of the low declination of the field and typically amounted to 5 hr of time per calendar date. The details of the individual pointings are: <pre> Pointing ID R.A. (J2000) DE. (J2000) rms sensitivity for final image ECDFS 1 03:33:22.25 -27:48:30.0 10.5 uJy ECDFS 2 03:32:55.12 -27:38:03.0 9.4 uJy ECDFS 3 03:32:00.88 -27:38:03.0 9.7 uJy ECDFS 4 03:31:33.75 -27:48:30.0 9.5 uJy ECDFS 5 03:32:00.88 -27:58:57.0 10.0 uJy ECDFS 6 03:32:55.12 -27:58:57.0 9.3 uJy </pre> The images corresponding to the six individual pointings were combined to form the final mosaic image (shown in Figure 1 of the reference paper). This HEASARC table contains the catalog of 883 radio sources (Table 3 in the reference paper) and also the catalog of 49 individual components of the 17 multi-component sources (Table 4 in the reference paper), so that there are a total of 932 entries in the present table. To allow users to easily distinguish these types of entry, the HEASARC created a parameter type_flag which is set to 'S' for the 883 source entries and to 'C' for the 49 component entries. The HEASARC created names for the sources following the standard CDS and IAU recommendations for position-based names and using the prefix of '[MBF2013]' for Miller, Bonzini, Fomalont (2013), the first 3 authors and the date of publication of the reference paper. For the components, we have used the names based on the positions of the parent sources and the suffixes 'A', 'B', etc, in order of increasing J2000.0 RA. Thus, for the multi-component source [MBF2013] J033115.0-275518 which has 3 components, there are 4 entries in this table, one for the entire source, and one for each component, e.g.: <pre> Name | type_flag | RA (J2000.0) Dec (J2000.0) [MBF2013] J033115.0-275518 | S | 03 31 15.04 | -27 55 18.8 [MBF2013] J033115.0-275518 A| C | 03 31 13.99 | -27 55 19.9 [MBF2013] J033115.0-275518 B| C | 03 31 15.06 | -27 55 18.9 [MBF2013] J033115.0-275518 C| C | 03 31 17.05 | -27 55 15.2 </pre> The 17 sources thought to consist of multiple components associated with a single host object are each listed with a single aggregate integrated flux density. Gaussian fits to the individual components associated with these sources are separately listed for their components This table was created by the HEASARC in May 2013 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/205/13">CDS Catalog J/ApJS/205/13</a> files table3.dat and table4.dat. This is a service provided by NASA HEASARC .
984. VLA Extended-Chandra Deep Field-South 1.4-GHz Sources Opt/IR Counterparts
ID:
ivo://nasa.heasarc/vlaecdfsoi
Title:
VLA Extended-Chandra Deep Field-South 1.4-GHz Sources Opt/IR Counterparts
Short Name:
VLAECDFSOI
Date:
07 Mar 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 .
985. VLA 1.5-GHz North Ecliptic Pole Survey
ID:
ivo://nasa.heasarc/vlanep
Title:
VLA 1.5-GHz North Ecliptic Pole Survey
Short Name:
VLA
Date:
07 Mar 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 .
986. VLA 6-GHz Observations of Low-Redshift SDSS QSOs
ID:
ivo://nasa.heasarc/lowzvlqvla
Title:
VLA 6-GHz Observations of Low-Redshift SDSS QSOs
Short Name:
LOWZVLQVLA
Date:
07 Mar 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 .
987. VLA GOODS-North Field 1.4-GHz Source Catalog
ID:
ivo://nasa.heasarc/vlagoodsn
Title:
VLA GOODS-North Field 1.4-GHz Source Catalog
Short Name:
VLAGOODSN
Date:
07 Mar 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 .
988. VLA Goulds Belt Survey Ophiuchus Complex Source Catalog
ID:
ivo://nasa.heasarc/vlagbsoph
Title:
VLA Goulds Belt Survey Ophiuchus Complex Source Catalog
Short Name:
VLAGBSOPH
Date:
07 Mar 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table contains results from large-scale (~2000 arcmin<sup>2</sup>), deep (~20 µJy), high-resolution (~1") radio observations of the Ophiuchus star-forming complex obtained with the Karl G. Jansky Very Large Array (JVLA) at wavelengths of 4 and 6 cm (frequencies of 7.5 and 4.5 GHz). In total, 189 sources were detected, 56 of them associated with known young stellar objects (YSOs), and 4 with known extragalactic objects; the other 129 remain unclassified, but most of them are most probably background quasars. The vast majority of the young stars detected at radio wavelengths have spectral types K or M, although four objects of A/F/B types and two brown dwarf candidates are also detected. At least half of these young stars are non-thermal (gyrosynchrotron) sources, with active coronae characterized by high levels of variability, negative spectral indices, and (in some cases) significant circular polarization. As expected, there is a clear tendency for the fraction of non-thermal sources to increase from the younger (Class 0/I or flat spectrum) to the more evolved (Class III or weak-line T Tauri) stars. The young stars detected both in X-rays and at radio wavelengths broadly follow a Gudel-Benz relation, but with a different normalization than the most radio-active types of stars. Finally, the authors detected a ~70 mJy compact extragalactic source near the center of the Ophiuchus core, which should be used as gain calibrator for any future radio observations of this region. The observations were obtained with the JVLA of the National Radio Astronomy Observatory (NRAO). 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 on three different epochs (2011 February 17/19, April 3/4, and May 4/6) typically separated from one another by a month. The angular resolution of the observations is of the order of 1 arcsecond. To identify sources in their observations, the authors used the images corresponding to the concatenation of the three epochs, which provided the highest sensitivity. The criteria used to consider a detection as firm were: (1) sources with reported counterparts and a flux larger than four times the rms noise of the area, or (2) sources with a flux larger than five times the rms noise of the area and without reported counterparts. The authors searched the literature for previous radio detections, and for counterparts at X-ray, optical, near-infrared, and mid-infrared wavelengths. The search was done in SIMBAD, and accessed all the major catalogs (listed explicitly in the footnote of Table 3 in the reference paper). Note that the Spitzer c2d catalog includes cross-references to other major catalogs which were taken into account in their counterpart search. The authors considered a radio source associated with a counterpart at another wavelengths if the separation between the two was below the combined uncertainties of the two data sets. This was about 1.5 arcseconds for the optical and infrared catalogs, but could be significantly larger for some of the radio catalogs (for instance, the NVSS has a positional uncertainty of about 5 arcseconds). The authors found that only 76 of the sources detected here had previously been reported at radio wavelengths (matches are listed in the radio_name parameter in such cases), while the other 113 are new radio detections. On the other hand, they found a total of 100 counterparts at other wavelengths. Note that there are a significant number of sources that were previously known at radio wavelengths and have known counterparts at other frequencies. As a consequence, the number of sources that were previously known (at any frequency) is 134, while 55 of the sources in this sample are reported here for the first time. The authors argue that most of these 55 objects are likely background sources. They note, however, that 18 of the 129 unclassified objects (55 identified here for the first time and 74 previously known at radio wavelengths) are compact, have a positive spectral index, or exhibit high variability. Since these latter two properties are not expected of quasars (which are certainly variable, but usually not strongly on such short timescale), but would be natural characteristics of young stars, the authors argue that a small population of YSOs might be present among the unclassified sources. This population could account for, at most, 15% of the unclassified sources, and possibly significantly less. This table was created by the HEASARC in July 2015 based on electronic versions of Tables 1, 3 and 5 from the reference paper, which were obtained from the CDS (Catalog J/ApJ/775/63 files table1.dat, table3.dat and table5.dat). This is a service provided by NASA HEASARC .
989. VLA Goulds Belt Survey Orion Complex Source Catalog
ID:
ivo://nasa.heasarc/vlagbsori
Title:
VLA Goulds Belt Survey Orion Complex Source Catalog
Short Name:
VLAGBSORI
Date:
07 Mar 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table contains results from a high-sensitivity (60 µJy), large-scale (2.26 deg<sup>2</sup>) survey obtained with the Karl G. Jansky Very Large Array (JVLA) as part of the Gould's Belt Survey (GBS) program. The authors detected 374 and 354 sources at 4.5 and 7.5 GHz, respectively. Of these, 148 are associated with previously known young stellar objects (YSOs). Another 86 sources previously unclassified at either optical or infrared wavelengths exhibit radio properties that are consistent with those of young stars. The overall properties of these sources at radio wavelengths such as their variability and radio to X-ray luminosity relation are consistent with previous results from the GBS. These detections provide target lists for follow-up Very Long Baseline Array radio observations to determine their distances, as YSOs are located in regions of high nebulosity and extinction, making it difficult to measure their optical parallaxes. The observations were obtained with the JVLA of the National Radio Astronomy Observatory (NRAO) in its A configuration. The observations of the 210 fields in the Orion Molecular Clouds A and B were obtained in three different epochs (2011 June 25 to July 4, July 23 to 30, and August 25 to 29, as described in Table 1 of the reference paper) typically separated from one another by a month. The 210 individual fields have been split into 7 maps, with 30 fields being observed per map, as follows: 12 in the lambda Ori region, 3 in L1622, 27 are shared between NGC 2068 and NGC 2071, 14 are shared between NGC 2023 and NGC 2024, 11 in the sigma Ori region, 109 in the Orion Nebula Cluster (ONC), 16 in L1641-N, 8 in L1641-C, and 10 in L1641-S (see Figures 1 to 7 in the reference paper). Two frequency sub-bands, each 1-GHz wide, and centered at 4.5 and 7.5 GHz, respectively, were recorded simultaneously. The authors achieved a nearly uniform rms noise of 60 µJy beam<sup>-1</sup> at both frequencies in all the regions. The only exception to this is in the Trapezium region due to nebular emission; there the noise was 200 µJy beam<sup>-1</sup> after excluding baselines smaller than 150 kilo-lambda during imaging to remove extended emission. Sources were identified through a visual inspection of the individual fields at 4.5 GHz during the cleaning and imaging process since an automated source identification was deemed to be not sufficiently advanced and produced results that were too unreliable. In particularly clustered regions such as the Trapezium and NGC 2024, in addition to standard imaging, data from all three epochs were combined into a single image for source identification purposes only to improve statistical significance of each detection. The authors detected a combined total of 374 sources among the three epochs for all of the regions. All sources but one had fluxes greater than five times the rms noise in at least one epoch. The remaining source, 'GBS-VLA J053518.67-052033.1', was detected at two epochs with maximum detection probability of 4.9 sigma in a single epoch data. It is found in the Trapezium region, and has known counterparts in other wavelength regimes. The authors cross-referenced their catalog of sources with previous major radio, infrared, optical and X-ray surveys of the regions published in the literature. They have generally considered sources in these surveys to be counterparts if they had positional coincidences less than 1 arcsecond, but have allowed for larger offsets if the combined uncertainty between the databases was large. Of 374 detected sources, 261 have been previously found at another wavelength region, while 113 are new detections. 146 sources have been detected in X-rays, 94 at optical wavelengths, 218 at infrared, and 63 in previous radio surveys. Of the previously identified sources, 1 is extragalactic, while the other 148 as young stellar objects (YSOs). Of the YSOs, 106 have been placed on the standard class system based on the IRAC color-color classification of Allen et al. (2004, ApJS, 154, 363). There are 11 Class 0/I, 26 Class II, and 70 Class III type stars. A total of 225 sources are either new detections or, to the authors' knowledge, have not been previously classified in the literature. Of these remaining objects, they have identified 86 as exhibiting variability or high levels of circular polarization. While the authors cannot exclude the possibility that any of them are extragalactic in nature, quasars are not expected to vary as strongly on timescales of few weeks to few months, and exhibit very weak circular polarization, so these sources (listed in Table 5 of the reference paper) are likely YSO candidates. Using the same criteria of variability and circular polarization would identify only 107 of the 148 previously-known YSOs; thus we cannot tell which of the remaining 139 unidentified sources are YSOs or extragalactic objects. This table was created by the HEASARC in July 2015 based on electronic versions of Tables 2 and 4 from the reference paper, which were obtained from the ApJ web site. This is a service provided by NASA HEASARC .
990. VLA Goulds Belt Survey Perseus Region Source Catalog
ID:
ivo://nasa.heasarc/vlagbsper
Title:
VLA Goulds Belt Survey Perseus Region Source Catalog
Short Name:
VLAGBSPER
Date:
07 Mar 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 .