- ID:
- ivo://nasa.heasarc/gmrtk2f1lf
- Title:
- Giant Metrewave Radio Telescope 150-MHz Survey of Kepler K2 Field 1
- Short Name:
- GMRTK2F1LF
- Date:
- 27 Sep 2024
- 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 .
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- ID:
- ivo://nasa.heasarc/gmrtspxfls
- Title:
- Giant Metrewave Radio Telescope Spitzer xFLS Field 610-MHz Radio Source Catalog
- Short Name:
- GMRTSPXFLS
- Date:
- 27 Sep 2024
- 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:
- 27 Sep 2024
- 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:
- 27 Sep 2024
- 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:
- 27 Sep 2024
- 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://CDS.VizieR/J/ApJS/149/343
- Title:
- Giant molecular clouds in M33
- Short Name:
- J/ApJS/149/343
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first interferometric ^12^CO (J=1->0) map of the entire H{alpha} disk of M33. The 13" diameter synthesized beam corresponds to a linear resolution of 50pc, sufficient to distinguish individual giant molecular clouds (GMCs). From these data we generated a catalog of 148 GMCs with an expectation that no more than 15 of the sources are spurious. The catalog is complete down to GMC masses of 1.5x10^5^M_{sun}_ and contains a total mass of 2.3x10^7^M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/ApJ/654/240
- Title:
- Giant molecular clouds in M31
- Short Name:
- J/ApJ/654/240
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Berkeley-Illinois-Maryland Association (BIMA) millimeter interferometer observations of giant molecular clouds (GMCs) along a spiral arm in M31. The observations consist of a survey using the compact configuration of the interferometer and follow-up, higher resolution observations on a subset of the detections in the survey. The data are processed using an analysis algorithm designed to extract GMCs and correct their derived properties for observational biases, thereby facilitating comparison with Milky Way data. The algorithm identifies 67 GMCs, of which 19 have a sufficient signal-to-noise ratio to accurately measure their properties. The GMCs in this portion of M31 are indistinguishable from those found in the Milky Way, having a similar size-line width relationship and distribution of virial parameters, confirming the results of previous, smaller studies. The velocity gradients and angular momenta of the GMCs are comparable to the values measured in M33 and the Milky Way, and in all cases are below expected values based on the local galactic shear. The studied region of M31 has an interstellar radiation field, metallicity, Toomre Q parameter, and midplane volume density similar to those of the inner Milky Way, so the similarity of GMC populations between the two systems is not surprising.
- ID:
- ivo://CDS.VizieR/J/A+A/542/A108
- Title:
- Giant molecular clouds in M33
- Short Name:
- J/A+A/542/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of a systematic CO(2-1) survey at 12" resolution covering most of the Local Group spiral M33, which, at a distance of 840kpc, is close enough for individual giant molecular clouds (GMCs) to be identified. The goal of this work is to study the properties of the GMCs in this subsolar metallicity galaxy. The CPROPS (Cloud PROPertieS) algorithm was used to identify 337 GMCs in M33, the largest sample to date for an external galaxy. The sample is used to study the GMC luminosity function, or mass spectrum under the assumption of a constant N(H_2_)/I_CO_ ratio.
- ID:
- ivo://CDS.VizieR/J/ApJ/772/107
- Title:
- Giant molecular clouds in nearby galaxies
- Short Name:
- J/ApJ/772/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We resolve 182 individual giant molecular clouds (GMCs) larger than 2.5x10^5^M_{sun}_ in the inner disks of 5 large nearby spiral galaxies (NGC 2403, NGC 3031, NGC 4736, NGC 4826, and NGC 6946) to create the largest such sample of extragalactic GMCs within galaxies analogous to the Milky Way. Using a conservatively chosen sample of GMCs most likely to adhere to the virial assumption, we measure cloud sizes, velocity dispersions, and ^12^CO(J=1-0) luminosities and calculate cloud virial masses. The average conversion factor from CO flux to H_2_ mass (or X_CO_) for each galaxy is 1-2x10^20^/cm2 (K.km/s)^-1^, all within a factor of two of the Milky Way disk value (~2x10^20^/cm2(K.km/s)^-1^). We find GMCs to be generally consistent within our errors between the galaxies and with Milky Way disk GMCs; the intrinsic scatter between clouds is of order a factor of two. Consistent with previous studies in the Local Group, we find a linear relationship between cloud virial mass and CO luminosity, supporting the assumption that the clouds in this GMC sample are gravitationally bound. We do not detect a significant population of GMCs with elevated velocity dispersions for their sizes, as has been detected in the Galactic center. Though the range of metallicities probed in this study is narrow, the average conversion factors of these galaxies will serve to anchor the high metallicity end of metallicity-X_CO_ trends measured using conversion factors in resolved clouds; this has been previously possible primarily with Milky Way measurements.
- ID:
- ivo://CDS.VizieR/J/ApJ/803/16
- Title:
- Giant molecular clouds in NGC4526 based on ^12^CO
- Short Name:
- J/ApJ/803/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a high spatial resolution (~20pc) of ^12^CO(2-1) observations of the lenticular galaxy NGC 4526. We identify 103 resolved giant molecular clouds (GMCs) and measure their properties: size R, velocity dispersion {sigma}_v_, and luminosity L. This is the first GMC catalog of an early-type galaxy. We find that the GMC population in NGC 4526 is gravitationally bound, with a virial parameter {alpha}~1. The mass distribution, dN/dM{propto}M^-2.39+/-0.03^, is steeper than that for GMCs in the inner Milky Way, but comparable to that found in some late-type galaxies. We find no size-line width correlation for the NGC 4526 clouds, in contradiction to the expectation from Larson's relation. In general, the GMCs in NGC 4526 are more luminous, denser, and have a higher velocity dispersion than equal-size GMCs in the Milky Way and other galaxies in the Local Group. These may be due to higher interstellar radiation field than in the Milky Way disk and weaker external pressure than in the Galactic center. In addition, a kinematic measurement of cloud rotation shows that the rotation is driven by the galactic shear. For the vast majority of the clouds, the rotational energy is less than the turbulent and gravitational energy, while the four innermost clouds are unbound and will likely be torn apart by the strong shear at the galactic center. We combine our data with the archival data of other galaxies to show that the surface density {Sigma} of GMCs is not approximately constant, as previously believed, but varies by ~3 orders of magnitude. We also show that the size and velocity dispersion of the GMC population across galaxies are related to the surface density, as expected from the gravitational and pressure equilibrium, i.e., {sigma}_v_R^-1/2^{propto}{Sigma}^1/2^.