- ID:
- ivo://CDS.VizieR/VIII/109
- Title:
- GLEAM III. South Galactic Pole
- Short Name:
- VIII/109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the South Galactic Pole (SGP) data release from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. These data combine both years of GLEAM observations at 72-231MHz conducted with the Murchison Widefield Array (MWA) and cover an area of 5,113 deg^2^ centred on the SGP at 20h40m<RA<05h04m and -48{deg}<Dec<-2{deg}. At 216MHz, the typical rms noise is ~5mJy/beam and the angular resolution ~2 arcmin. The source catalogue contains a total of 108851 components above 5{sigma}, of which 77 per cent have measured spectral indices between 72 and 231MHz. Improvements to the data reduction in this release include the use of the GLEAM Extragalactic catalogue as a sky model to calibrate the data, a more efficient and automated algorithm to deconvolve the snapshot images, and a more accurate primary beam model to correct the flux scale. This data release enables more sensitive large-scale studies of extragalactic source populations as well as spectral variability studies on a one-year timescale.
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- ID:
- ivo://CDS.VizieR/VIII/107
- Title:
- GLEAM sources ionospheric position shifts
- Short Name:
- VIII/107
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Nearly 200 hours of observing with the Murchison Widefield Array (MWA) radio telescope during the Galactic and Extra-galactic All-sky MWA (GLEAM) survey were used to assemble images of ionospheric structure. These images cover a nearly 50 degree-wide area on the sky at a cadence of 10 minutes over many 5-7 hours-long observing runs. They are generated by tracking the apparent motions of ~200-800 cosmic radio sources caused by changes in the transverse gradient of the ionospheric total electron content. Spectral analysis of these images revealed that the dataset was dominated by three distinct signatures. The first is consistent with field-aligned structures within the topside ionosphere/lower plasmasphere previously imaged with the MWA. The second are structures that are relatively large and aligned nearly east/west. Regional weather data implies that these are preferentially detected when there is a noticeable shear within the sub- tropical jet stream, which passes near the MWA. This suggests that this signature may be related to gravity waves launched by jet stream shear. The final signature is consistent with the properties of so-call electro-buoyancy waves that are known to occur at midlatitudes at night. Detections of these were more common when regional sporadic-E was present, supporting a proposed connection between these waves and polarization electric fields that may arise within sporadic-E. We discuss the implications for future observations with the Square Kilometer Array.
- ID:
- ivo://CDS.VizieR/II/293
- Title:
- GLIMPSE Source Catalog (I + II + 3D)
- Short Name:
- II/293
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galactic Legacy Infrared Midplane Survey Extraordinaire (GLIMPSE), is a survey of Galactic Plane central parts made with the Infrared Array Camera (IRAC) aboard the Spitzer Space Telescope (SST). It covers approximately 220 square degrees, between galactic longitudes +/-65{deg} and +/-1{deg} in galactic latitude (up to 4.2{deg} in the central parts). The four IRAC bands are centered at approximately 3.6, 4.5, 5.8 and 8.0{mu}m. The GLIMPSE combines the 3 surveys: * GLIMPSE-I covers the longitude ranges |l|=10--65{deg} and the latitude range |b|<=1{deg} (Benjamin et al. 2003PASP..115..953B) * GLIMPSE-II covers the longitude range of |l|<=10{deg}, and a latitude range |b|<=1{deg} from |l|=5--10, |b|<=1.5 for |l|=2--5, and |b|<=2{deg} for |l|<=2. GLIMPSE-II coverage excludes the Galactic center region |l|<=1, |b|<=0.75 observed by the GALCEN GO program (PID=3677). * GLIMPSE-3D adds vertical extensions up to |b|=4.2{deg} near the galactic center, and up to |b|=3{deg} in selected other parts of the Galaxy (+/-10, 18.5, 25, 30, and -15 (345){deg}). GLIMPSE-II had two-epoch coverage for a total of three visits on the sky. The observations consisted of two 1.2 second integrations at each position in the first epoch of data taking (September 2005) and a single 1.2 second integration at each position six months later (April 2006). The highly reliable v2.0 GLIMPSEII Catalog (v2.0_GLMIIC) consists of point sources that are detected at least twice in one band and at least once in an adjacent band and a S/N > 5 cut for the band with the two detections. There are also faint and bright flux limits on the Catalog entries. The more complete v2.0 Archive (v2.0_GLMIIA) has less stringent criteria, namely two detections in any bands, those detections having a S/N > 5. The IRAC data were bandmerged with the 2MASS All-Sky Point Source Catalog. See the GLIMPSEII v2.0 Data Products & Data Delivery document for more details. The catalog available from CDS merges the 3 surveys GLIMPSE-I (v2.0), GLIMPSE-II (v2.0), and GLIMPSE-3D; Catalog and Archive records are also merged here. In the regions of overlap between the 3 surveys (e.g. longitude around 10{deg}) preference was given to (1) GLIMPSE-II, as recommended in the GLIMPSE documents of May 2007 (glimpse1_v2.0.pdf) and April 2008 (glimpse2-v2.0.pdf); (2) GLIMPSE-I, and (3) GLIMPSE-3D sources. Sources from different surveys were merged if their position is closer than 0.1arcsec. Documents and a document describing in detail the point source photometry steps, see http://www.astro.wisc.edu/glimpse/docs.html
- ID:
- ivo://CDS.VizieR/J/AJ/136/159
- Title:
- Global 86GHz VLBI survey of compact radio sources
- Short Name:
- J/AJ/136/159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a large 86GHz global very long baseline interferometry (VLBI) survey of compact radio sources. The main goal of the survey is to increase by factors of 3-5 the total number of objects accessible for future 3mm VLBI imaging. The survey observations reach a baseline sensitivity of 0.1Jy and an image sensitivity of better than 10mJy/beam. A total of 127 compact radio sources have been observed. The observations have yielded images for 109 sources, extending the database of the sources imaged at 86GHz with VLBI observation by a factor of 5, and only six sources have not been detected. The remaining 12 objects have been detected but could not be imaged due to insufficient closure phase information.
- ID:
- ivo://CDS.VizieR/J/ApJS/171/101
- Title:
- Globular clusters in the ACS Virgo cluster survey
- Short Name:
- J/ApJS/171/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze the luminosity function of the globular clusters (GCs) belonging to the early-type galaxies observed in the ACS Virgo Cluster Survey. We have obtained maximum likelihood estimates for a Gaussian representation of the globular cluster luminosity function (GCLF) for 89 galaxies. We have also fit the luminosity functions with an "evolved Schechter function", which is meant to reflect the preferential depletion of low-mass GCs, primarily by evaporation due to two-body relaxation, from an initial Schechter mass function similar to that of young massive clusters in local starbursts and mergers. We find a highly significant trend of the GCLF dispersion {sigma} with galaxy luminosity, in the sense that the GC systems in smaller galaxies have narrower luminosity functions. The GCLF dispersions of our Galaxy and M31 are quantitatively in keeping with this trend, and thus the correlation between {sigma} and galaxy luminosity would seem more fundamental than older notions that the GCLF dispersion depends on Hubble type. We show that this narrowing of the GCLF in a Gaussian description is driven by a steepening of the cluster mass function above the classic turnover mass, as one moves to lower luminosity host galaxies. In a Schechter function description, this is reflected by a steady decrease in the value of the exponential cutoff mass scale. We argue that this behavior at the high-mass end of the GC mass function is most likely a consequence of systematic variations of the initial cluster mass function rather than long-term dynamical evolution.
- ID:
- ivo://CDS.VizieR/J/A+A/651/A86
- Title:
- GLOSTAR Galactic plane survey. II. SNR.
- Short Name:
- J/A+A/651/A86
- Date:
- 17 Jan 2022 00:20:41
- Publisher:
- CDS
- Description:
- The properties of the population of Galactic supernova remnants (SNRs) are essential to our understanding of the dynamics of the interstellar medium (ISM) in the Milky Way. However, the completeness of the catalog of Galactic SNRs is expected to be only ~30%, with on order 700 SNRs yet to be detected. Deep interferometric radio continuum surveys of the Galactic plane help in rectifying this apparent deficiency by identifying low surface brightness SNRs and compact SNRs that have not been detected in previous surveys. However, SNRs are routinely confused with HII regions, which can have similar radio morphologies. Radio spectral index, polarization, and emission at mid-infrared (MIR) wavelengths can help distinguish between SNRs and HII regions. We aim to identify SNR candidates using continuum images from the Karl G. Jansky Very Large Array GLObal view of the STAR formation in the Milky Way (GLOSTAR) survey. GLOSTAR is a C-band (4-8GHz) radio wavelength survey of the Galactic plane covering 358{deg}>=l<=60{deg}, |b|<=1{deg}. The continuum images from this survey, which resulted from observations with the most compact configuration of the array, have an angular resolution of 18''. We searched for SNRs in these images to identify known SNRs, previously identified SNR candidates, and new SNR candidates. We study these objects in MIR surveys and the GLOSTAR polarization data to classify their emission as thermal or nonthermal. We identify 157 SNR candidates, of which 80 are new. Polarization measurements provide evidence of nonthermal emission from 9 of these candidates. We find that two previously identified candidates are filaments. We also detect emission from 91 of the 94 known SNRs in the survey region. Four of these are reclassified as HII regions following detection in MIR surveys. The better sensitivity and resolution of the GLOSTAR data have led to the identification of 157 SNR candidates, along with the reclassification of several misidentified objects. We show that the polarization measurements can identify nonthermal emission, despite the diffuse Galactic synchrotron emission. These results underscore the importance of higher resolution and higher sensitivity radio continuum data in identifying and confirming SNRs.
- ID:
- ivo://CDS.VizieR/J/A+A/627/A175
- Title:
- GLOSTAR. Radio Source Catalogue I
- Short Name:
- J/A+A/627/A175
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radio continuum surveys of the Galactic plane are an excellent way to identify different source populations such as planetary nebulae, HII regions, and radio stars and characterize their statistical properties. The Global View of Star Formation in the Milky Way (GLOSTAR) survey will study the star formation in the Galactic plane between -2{deg}<l<85{deg} and |b|<1{deg} with unprecedented sensitivity in both flux density (~40uJy/beam) and range of angular scales (~1.5" to the largest radio structures in the Galaxy). In this paper we present the first results obtained from a radio continuum map of a 16-square-degree-sized region of the Galactic plane centered on l=32{deg} and b=0{deg} (28{deg}<l<36{deg} and |b|<1{deg}). This map has a resolution of 18" and a sensitivity of 60-150uJy/beam. We present data acquired in 40 hours of observations with the VLA in D-configuration. Two 1GHz wide sub-bands were observed simultaneously and they were centered at 4.7 and 6.9GHz. These data were calibrated and imaged using the Obit software package. The source extraction was performed using the BLOBCAT software package and verified through a combination of visual inspection and cross-matching with other radio and mid-infrared surveys. The final catalog consists of 1575 discrete radio sources and 27 large scale structures (including W43 and W44). By crossmatching with other catalogs and calculating the spectral indices (S({nu}){prop.to}{nu}^{alpha}^), we have classified 231 continuum sources as HII regions, 37 as ionization fronts, and 46 as planetary nebulae. The longitude and latitude distribution and negative spectral indices are all consistent with the vast majority of the unclassified sources being extragalactic background sources. We present a catalog of 1575 radio continuum sources and discuss their physical properties, emission nature, and relation to previously reported data. These first GLOSTAR results have increased the number of reliable HII regions in this part of the Galaxy by a factor of four.
- ID:
- ivo://CDS.VizieR/J/A+A/549/A55
- Title:
- GMRT 153MHz (2m) Radio Mini Survey I.
- Short Name:
- J/A+A/549/A55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present wide area, deep, high-resolution 153MHz GMRT observations of the NOAO Bootes field, adding to the extensive, multi-wavelength data of this region. The observations, data reduction, and catalogue construction and description are described here. The seven pointings produced a final mosaic covering 30 square degrees with a resolution of 25". The rms noise is 2mJy/beam in the centre of the image, rising to 4-5mJy/beam on the edges, with an average of 3mJy/beam. Seventy-five per cent of the area has an rms <4mJy/beam. The extracted source catalogue contains 1289 sources detected at 5{sigma}, of which 453 are resolved. We estimate the catalogue to be 92 per cent reliable and 95 per cent complete at an integrated flux density limit of 14mJy. The flux densities and astrometry have been corrected for systematic errors. We calculate the differential source counts which are in good agreement with those in the literature and provide an important step forward in quantifying the source counts at these low frequencies and low flux densities. The GMRT 153MHz sources have been matched to the 1.4GHz NVSS and 327MHz WENSS catalogues and spectral indices were derived.
- ID:
- ivo://CDS.VizieR/J/MNRAS/464/3357
- Title:
- GMRT 610-MHz observations of the AMI001 field
- Short Name:
- J/MNRAS/464/3357
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 610-MHz Giant Metrewave Radio Telescope observations of 0.84deg^2^ of the AMI001 field (centred on 00h23m10s, +31d53') with an rms noise of 18microJy/beam in the centre of the field. A total of 955 sources are detected, and 814 are included in the source count analysis. The source counts from these observations are consistent with previous work. We have used these data to study the spectral index distribution of a sample of sources selected at 15.7GHz from the recent deep extension to the Tenth Cambridge (10C) survey. The median spectral index, alpha, (where S{prop.to}nu^-alpha^^) between 0.08<S_15.7GHz/mJy<0.2 is 0.32+/-0.14, showing that star-forming galaxies, which have much steeper spectra, are not contributing significantly to this population. This is in contrast to several models, but in agreement with the results from the 10C ultra-deep source counts; the high-frequency sky therefore continues to be dominated by radio galaxies down to S_15.7GHz_=0.1mJy.
- ID:
- ivo://CDS.VizieR/J/A+A/551/A24
- Title:
- GMRT Radio Halo Cluster Survey diffuse sources
- Short Name:
- J/A+A/551/A24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To gain further insight on the origin of diffuse radio sources in galaxy clusters and their connection with cluster merger processes, we performed GMRT low frequency observations of the radio halos, relics and new candidates belonging to the GMRT Radio Halo Cluster Sample first observed at 610MHz. Our main aim was to investigate their observational properties and integrated spectrum at frequencies below 610MHz.
