- ID:
- ivo://nasa.heasarc/gmrtlbdsly
- Title:
- Giant Metrewave Radio Telescope LBDS-Lynx Region 150-MHz Radio Source Catalog
- Short Name:
- GMRTLBDSLY
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- It has been known for nearly three decades that high-redshift radio galaxies exhibit steep radio spectra, and hence ultrasteep spectrum radio sources provide candidates for high-redshift radio galaxies. Nearly all radio galaxies with z > 3 have been found using this redshift-spectral index correlation. The authors have started a program with the Giant Metrewave Radio Telescope (GMRT) to exploit this correlation at flux density levels about 10 to 100 times deeper than the known high-redshift radio galaxies which were identified primarily using the already available radio catalogs. In their program, they have obtained deep, high-resolution radio observations at 150 MHz with the GMRT for several "deep" fields which are well studied at higher radio frequencies and in other bands of the electromagnetic spectrum, with the aim to detect candidate high-redshift radio galaxies. In their paper, they present results from the deep 150-MHz observations of the LBDS (Leiden-Berkeley Deep Survey) Lynx field, which has been already imaged at 327, 610 and 1412 MHz with the Westerbork Synthesis Radio Telescope (WSRT) and at 1400 and 4860 MHz with the Very Large Array (VLA). The counterparts for the 150-MHz sources at higher radio frequencies were searched within a 20-arcsec radius from the 150-MHz position. The 150-MHz image made with the GMRT has an rms noise of ~ 0.7 mJy beam<sup>-1</sup> and a resolution of ~ 19 x 15 arcsec<sup>2</sup>. It is the deepest low-frequency image of the LBDS-Lynx field. The source catalog of this field at 150 MHz has 765 sources down to ~ 20% of the primary beam response, covering an area of about 15 deg<sup>2</sup>. The spectral index was estimated by cross-correlating each source detected at 150 MHz with the available observations at 327, 610, 1400 and 4860 MHz and also using available radio surveys such as the Westerbork Northern Sky Survey (WENSS) at 327 MHz and the NRAO VLA Sky Survey (NVSS) and the Faint Images of the Radio Sky at Twenty-cm (FIRST) survey at 1400 MHz. A total of 639 sources out of 765 (83%) have spectral indices determined. The remaining 17% of the sources are mostly weak radio sources with a median flux density of ~ 9 mJy, or fall in the regions where deep observations at higher frequencies do not exist. The median spectral index of the sample is 0.78. The authors find about 150 radio sources with spectra steeper than 1. About two-thirds of these are not detected in the Sloan Digital Sky Survey (SDSS), hence are strong candidate high-redshift radio galaxies, which need to be further explored with deep infrared imaging and spectroscopy to estimate the redshift. The list of the 98 such steep-spectrum sources lacking SDSS counterparts is given in Table 4 of the published paper. This table was created by the HEASARC in February 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/405/436">CDS Catalog J/MNRAS/405/436</a> file table3.dat. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/gmrtlhcat2
- Title:
- Giant Metrewave Radio Telescope Lockman Hole 610-MHz Radio Source Catalog 2
- Short Name:
- GMRTLHCAT2
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a source catalog based on further observations of the Lockman Hole field, made with the Giant Metrewave Radio Telescope at 610 MHz with an angular resolution of 6 x 5 arcsec<sup>2</sup>. These complement this group's earlier observations of the central ~ 5 deg<sup>2</sup> of the Lockman Hole (Garn et al. 2008, MNRAS, 387, 1037, the HEASARC Browse table GMRTLHCAT) by covering a further ~ 8 deg<sup>2</sup> area, with an rms noise down to ~ 80 microJansky/beam (µJy/beam). A catalog of 4934 radio sources in both the inner and outer regions of the Lockman Hole is presented in this table. The earlier survey had 12 pointings covering ~ 5 square degrees in the center of the Lockman Hole, and herein a further 26 pointings in the outer parts of the Lockman Hole are added, to cover a total of ~ 14 square degrees. To match the earlier survey, the images were made with a resolution of 6" x 5", at a position angle of +45 degrees. The majority of the new pointings have an rms noise of ~80 µJy/beam before the primary beam correction, but the noise in the west - particularly near the very bright source 3C244.1 - is worse. This table was created by the HEASARC in February 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/BASI/38.103">CDS Catalog J/BASI/38.103</a> file gmrtlh2.cat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gmrtlhcat
- Title:
- Giant Metrewave Radio Telescope Lockman Hole 610-MHz Radio Source Catalog
- Short Name:
- GMRTLHCAT
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a source catalog based on observations of the Lockman Hole with the Giant Metrewave Radio Telescope (GMRT) taken at 610 MHz (49 cm). Twelve pointings were observed, covering a total area of ~5 deg<sup>2</sup> with a resolution of 6 x 5 arcsec<sup>2</sup>, position angle +45 degrees. The majority of the pointings have an rms noise of ~ 60 µJy/beam (µJy/beam) before correction for the attenuation of the GMRT primary beam. The techniques used for data reduction and the production of a mosaicked image of the region are described in the reference paper, where the final mosaic is presented, along with a catalog of 2845 sources detected above the 6-sigma threshold which is contained in this table. In the paper, radio source counts are calculated at 610 MHz and combined with existing 1.4-GHz source counts, in order to show that pure luminosity evolution of the local radio luminosity functions for active galactic nuclei and starburst galaxies is sufficient to account for the two source counts simultaneously. The 'central region' of the Lockman Hole, consisting of 12 pointings spaced by 36 arcminutes in a hexagonal pattern (shown in Fig. 1 of the reference paper) was observed on 2004 July 24 and 25 using the GMRT. The observations were made in two 16-MHz sidebands centered on 610 MHz, each split into 128 spectral channels, with a 16.9s integration time. This table was created by the HEASARC in February 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/387/1037">CDS Catalog J/MNRAS/387/1037</a> file catalog.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gmrtlhcat3
- Title:
- Giant Metrewave Radio Telescope Lockman Hole 610-MHz Radio Source Catalog 3
- Short Name:
- GMRTLHCAT3
- 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 1585 sources found in the LH field at 610 MHz by the GMRT. For 19 of the sources which have multiple components, the 34 individual components are listed as well. Thus, the final table contains 1619 (1585 + 34) 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 table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gmrtk2f1lf
- Title:
- Giant Metrewave Radio Telescope 150-MHz Survey of Kepler K2 Field 1
- Short Name:
- GMRTK2F1LF
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains some of the results from the first dedicated radio continuum survey of a Kepler K2 mission field, Field 1, covering the North Galactic Cap. The survey was wide-field, contemporaneous, multi-epoch, and multi-resolution in nature and was conducted at low radio frequencies between 140 and 200 MHz. The multi-epoch and ultra-wide-field (but relatively low-resolution) part of the survey was provided by 15 nights of observation using the Murchison Widefield Array (MWA) over a period of approximately a month, contemporaneous with K2 observations of this field. The multi-resolution aspect of the survey was provided by the low-resolution (4 arcminutes) MWA imaging, complemented by non-contemporaneous but much higher resolution (20 arcseconds) observations using the Giant Metrewave Radio Telescope (GMRT). The survey is, therefore, sensitive to the details of radio structures across a wide range of angular scales. Consistent with other recent low radio frequency surveys, no significant radio transients or variables were detected in the survey. The resulting source catalogs consist of 1,085 and 1,468 detections in the two MWA observation bands (centered at 154 and 185 MHz, respectively) and 7,445 detections in the GMRT observation band (centered at 148 MHz), over 314 square degrees. The survey is presented as a significant resource for multi-wavelength investigations of the more than 21,000 target objects in the K2 field. In the reference paper, the authors briefly examined their survey data against K2 target lists for dwarf star types (stellar types M and L) that had been known to produce radio flares. This survey included contemporaneous observations of the K2 Field 1 made with the MWA and historical (from 2010-2012) observations made with the Tata Institute of Fundamental Research (TIFR) GMRT Sky Survey (TGSS; see <a href="http://tgss.ncra.tifr.res.in/">http://tgss.ncra.tifr.res.in/</a>), via the TGSS Alternative Data Release 1 (ADR1; Intema et al. 2016, in prep.). The MWA and GMRT are radio telescopes operating at low radio frequencies (approximately 140-200 MHz for the work described here). The K2 mission Campaign 1 was conducted on Field 1 (center at J2000.0 coordinates RA of 11:35:45.51 and Dec of +01:25:02.28;), covering the North Galactic Cap, between 2014 May 30 and August 21. A full survey of the radio sky at 150 MHz as visible from the GMRT was performed within the scope of the PI-driven TGSS project between 2010 and early 2012, covering the declination range from -55 to +90 degrees. Summarizing the observational parameters as given on the TGSS project website (<a href="http://tgss.ncra.tifr.res.in/150MHz/obsstrategy.html">http://tgss.ncra.tifr.res.in/150MHz/obsstrategy.html</a>), the survey consists of more than 5,000 pointings on an approximate hexagonal grid. Data were recorded in full polarization (RR, LL, RL, LR) every 2 seconds, in 256 frequency channels across 16 MHz of bandwidth (140-156 MHz). Each pointing was observed for about 15 minutes, split over three or more scans spaced in time to improve UV-coverage. Typically, 20-40 pointings were grouped together into single night-time observing sessions, bracketed and interleaved by primary (flux density and bandpass) calibrator scans on 3C48, 3C147, and/or 3C286. Interleaving secondary (phase) calibrator scans on a variety of standard phase calibrators were also included, but were typically too faint to be of significant benefit at these frequencies. The single epoch TGSS image was processed in the same way as each of the MWA images using the background and noise characterization source finding techniques outlined in Section 3.1.3 of the reference paper. A source catalog was produced from the single TGSS image. For the high-resolution TGSS images, the sources were resolved in some cases and so morphology information is included in this catalog. The final set of MWA images after source finding yielded a total of 1,085 radio sources at 154 MHz, and 1,471 sources at 185 MHz over 314 square degrees, at an angular resolutions of ~4 arcminutes: this MWA catalog is contained in the HEASARC table <a href="/W3Browse/radio-catalog/mwak2f1lfc.html">MWAK2F1HFC</a>, which thus has 1,085 + 1,471 = 2,556 entries. The GMRT images, after source finding, yielded a total of 7,445 radio sources over the same field, at an angular resolution of ~0.3 arcminutes: this GMRT source catalog is contained in the present HEASARC table. Thus, the overall survey covers multiple epochs of observation, spans approximately 140-200 MHz, is sensitive to structures on angular scales from arcseconds to degrees, and the MWA part is contemporaneous with the K2 observations of the field over a period of approximately one month. This table was created by the HEASARC in December 2016 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/AJ/152/82">CDS Catalog J/AJ/152/82</a> file table3.dat (the GMRT Kepler 2 Field 1 source catalog). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gmrtspxfls
- Title:
- Giant Metrewave Radio Telescope Spitzer xFLS Field 610-MHz Radio Source Catalog
- Short Name:
- GMRTSPXFLS
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a source catalog based on observations of the Spitzer extragalactic First Look Survey (xFLS) field taken at 610 MHz with the Giant Metrewave Radio Telescope (GMRT). Seven individual pointings were observed, covering a total area of ~ 4 square degrees with a resolution of 5.8 x 4.7 arcsec<sup>2</sup>, position angle 60 degrees. The rms noise at the center of the pointings is between 27 and 30 microJansky (µJy) before correction for the GMRT primary beam. The techniques used for data reduction and production of a mosaicked image of the region are described in the reference paper, where the final mosaic, along with a catalog of 3944 sources detected above a ~ 5-sigma threshold, are presented. The survey complements existing radio and infrared data available for this region. For further details of the surveys and data analysis procedures, please refer to the published paper. This table contains the xFLS catalog of 3944 610-MHz radio sources detected by the GMRT, the 05-May-2008 (Release 1.1) version provided to the CDS by the co-author Sally Hales (MRAO, Cambridge). In this version, a rounding error in the right ascension and declination positions listed for some sources in the original 10-May-2007 (Release 1.0) version has been corrected. The source IAU designations remain unchanged, having been based on the correctly computed positions throughout. The main purpose in correcting the positions was to eliminate sporadic mismatches between IAU designation and listed position in the first data release. In other respects the effect on the positions is negligible. This table was created by the HEASARC in February 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/376/1251">CDS catalog J/MNRAS/376/1251</a> file gmrtfls.dat, the release 1.1 (05-May-2008) version. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gmrtvvdsvl
- Title:
- Giant Metrewave Radio Telescope VVDS-VLA Deep Field 610-MHz Radio Source Catalog
- Short Name:
- GMRTVVDSVL
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the 5-sigma catalog at 610 MHz of the VIMOS VLT Deep Survey-Very Large Array (VVDS-VLA) deep field obtained from Giant Metrewave Radio Telescope (GMRT) observations. The field is located at RA, Dec = 02:26:00, -04:30:00 (J2000) and covers a 1-square degree area. The GMRT observations imaged the whole 1 square degree field with an angular resolution of 6 arcseconds and an average sensitivity of about 50 µJy/beam. The catalog lists 514 radio sources, 17 of which are fitted with multiple components (between 2 and 5). For these multiple sources, each component (A, B, etc.) is listed separately, and the entire source (indicated by the suffix T in the name) is also listed. Thus, there are 557 entries in this table, 43 of which correspond to multiple components. This table was created by the HEASARC in February 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/463/519">CDS Catalog J/A+A/463/519</a> file table.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gmrtxl240m
- Title:
- Giant Metrewave Radio Telescope XMM Large Scale Structure 240-MHz Source Catalog
- Short Name:
- GMRTXL240M
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The low-frequency radio survey of the XMM-Large Scale Structure (XMM-LSS) field centered at RA (J2000) = 2<sup>h</sup>24<sup>m</sup>00<sup>s</sup>, Dec (J2000) = -4<sup>0</sup>09'47" aims to study the connection between the extragalactic radio source populations and their environment as traced by X-ray and optical emission. In their paper, the authors present new radio observations of the XMM-LSS field carried out using the Giant Meterwave Radio Telescope (GMRT) at 240 and 610 MHz. These observations complement the observations presented by Cohen at al. (2003, ApJ, 591, 640; <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/591/640">CDS Cat. <J/ApJ/591/640></a>) and Tasse et al. (2006, A&A, 456, 791; <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/456/791">CDS Cat. <J/A+A/456/791></a>) at 74 and 325 MHz with the Very Large Array (VLA). At 240 and 610 MHz, the authors reach noise levels of ~2.5 and ~0.3 mJy/beam, leading to the detection of 466 and 769 sources over 18.0 and 12.7 degree<sup>2</sup> with resolutions of 14.7 arcseconds and 6.5 arcseconds, respectively. Combining these data with the available source lists at 74 MHz, 325 MHz (Tasse et al., 2006) and 1400MHz (NVSS), the authors built a multifrequency catalog containing 1611 radio sources. They checked for consistency of the astrometry and flux density estimates. They fit a simple synchrotron radiation model to the flux density measurements of the 318 radio sources that were detected in at least 4 bands. While ~26% of them showed signature of spectral ageing, ~6% showed self absorption. This table contains the GMRT 240-MHz source list, comprising 388 single sources and 183 components of multiple sources, for a total of 571 entries. For the multiple sources, each component (A, B, etc.) is listed separately, in order of decreasing brightness. This table was created by the HEASARC in February 2012 based on CS Catalog J/A+A/471/1105 file table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gmrtxl610m
- Title:
- Giant Metrewave Radio Telescope XMM Large Scale Structure 610-MHz Source Catalog
- Short Name:
- GMRTXL610M
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The low-frequency radio survey of the XMM-Large Scale Structure (XMM-LSS) field centered at RA (J2000) = 2<sup>h</sup>24<sup>m</sup>00<sup>s</sup>, Dec (J2000) = -4<sup>0</sup>09'47" aims to study the connection between the extragalactic radio source populations and their environment as traced by X-ray and optical emission. In their paper, the authors present new radio observations of the XMM-LSS field carried out using the Giant Meterwave Radio Telescope (GMRT) at 240 and 610 MHz. These observations complement the observations presented by Cohen at al. (2003, ApJ, 591, 640; <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/591/640">CDS Cat. <J/ApJ/591/640></a>) and Tasse et al. (2006, A&A, 456, 791; <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/456/791">CDS Cat. <J/A+A/456/791></a>) at 74 and 325 MHz with the Very Large Array (VLA). At 240 and 610 MHz, the authors reach noise levels of ~2.5 and ~0.3 mJy/beam, leading to the detection of 466 and 769 sources over 18.0 and 12.7 degree<sup>2</sup> with resolutions of 14.7 arcseconds and 6.5 arcseconds, respectively. Combining these data with the available source lists at 74 MHz, 325 MHz (Tasse et al., 2006) and 1400MHz (NVSS), the authors built a multifrequency catalog containing 1611 radio sources. They checked for consistency of the astrometry and flux density estimates. They fit a simple synchrotron radiation model to the flux density measurements of the 318 radio sources that were detected in at least 4 bands. While ~26% of them showed signature of spectral ageing, ~6% showed self absorption. This table contains the GMRT 610-MHz source list, comprising 592 single sources and 445 components of multiple sources, for a total of 1037 entries. For the multiple sources, each component (A, B, etc.) is listed separately, in order of decreasing brightness. This table was created by the HEASARC in February 2012 based on CS Catalog J/A+A/471/1105 file table4.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gb6
- Title:
- Green Bank 6-cm (GB6) Radio Source Catalog
- Short Name:
- GB6
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the Green Bank 6-cm (GB6) Radio Source Catalog. The Green Bank 4.85 GHz (6-cm wavelength) survey (Condon J.J., Broderick J.J., Seielstad G.A., Douglas K., & Gregory P.C. in 1994AJ....107.1829C) was made with the NRAO seven-beam receiver on the (former) 91m telescope during 1986 November and 1987 October. The final set of sky maps covering the declination band 0 deg < Dec. < +75 deg was constructed with data from both epochs. Its noise and position errors are nearly a factor of 2^(1/2) smaller than in the epoch 1987 maps, from which the 87GB Catalog (<a href="https://cdsarc.cds.unistra.fr/ftp/cats/VIII/14">CDS Catalog <VIII/14></a>) of 54,579 sources stronger than S ~ 25mJy was extracted. Therefore, the new maps were used to make the GB6 catalog of 75,162 discrete sources with angular sizes phi <= 10.5 arcmin and flux densities S >= 18mJy. The GB6 weighted differential source counts S^(5/2)n(S) between 18 mJy and 7 Jy agree well with evolutionary models based on independent data. This table was created by the HEASARC in July 2003 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VIII/40">CDS Catalog <VIII/40></a>. This is a service provided by NASA HEASARC .
