- ID:
- ivo://CDS.VizieR/J/AJ/138/1032
- Title:
- Filling in the gaps in the 4.85GHz sky
- Short Name:
- J/AJ/138/1032
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe a 4.85GHz survey of bright, flat-spectrum radio sources conducted with the Effelsberg 100m telescope in an attempt to improve the completeness of existing surveys, such as CRATES. We report the results of these observations and of follow-up 8.4GHz observations with the VLA of a subset of the sample. We comment on the connection to the Wilkinson Microwave Anisotropy Probe point source catalog and on the survey's effectiveness at supplementing the CRATES sky coverage.
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- ID:
- ivo://CDS.VizieR/J/AJ/130/2473
- Title:
- Fine-scale structure in 250 sources at 15GHz
- Short Name:
- J/AJ/130/2473
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have examined the compact structure in 250 flat-spectrum extragalactic radio sources using interferometric fringe visibilities obtained with the Very Long Baseline Array (VLBA) at 15GHz. With projected baselines out to 440M{lambda}, we are able to investigate source structure on typical angular scales as small as 0.05mas.
- ID:
- ivo://CDS.VizieR/J/ApJ/862/L2
- Title:
- First detection of HCOOH in TW Hya disk with ALMA
- Short Name:
- J/ApJ/862/L2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation of asteroids, comets, and planets occurs in the interior of protoplanetary disks during the early phase of star formation. Consequently, the chemical composition of the disk might shape the properties of the emerging planetary system. In this context, it is crucial to understand whether and what organic molecules are synthesized in the disk. In this Letter, we report the first detection of formic acid (HCOOH) toward the TW Hydrae protoplanetary disk. The observations of the trans-HCOOH 6_(1,6)-5(1,5)_ transition were carried out at 129GHz with Atacama Large Millimeter/Submillimeter Array (ALMA). We measured a disk-averaged gas-phase t-HCOOH column density of ~(2-4)x10^12^cm^-2^, namely as large as that of methanol. HCOOH is the first organic molecule containing two oxygen atoms detected in a protoplanetary disk, a proof that organic chemistry is very active, albeit difficult to observe, in these objects. Specifically, this simplest acid stands as the basis for synthesis of more complex carboxylic acids used by life on Earth.
- ID:
- ivo://CDS.VizieR/J/AJ/130/1977
- Title:
- FIRST-Optical-VLA survey for lensed radio lobes
- Short Name:
- J/AJ/130/1977
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a survey for gravitationally lensed radio lobes. Lensed lobes are a potentially richer source of information about galaxy mass distributions than lensed point sources, which have been the exclusive focus of other recent surveys. Our approach is to identify radio lobes in the Faint Images of the Radio Sky at Twenty cm (FIRST, Cat. <VIII/71>) catalog and then search optical catalogs for coincident foreground galaxies, which are candidate lensing galaxies. We then obtain higher resolution images of these targets at both optical and radio wavelengths and obtain optical spectra for the most promising candidates. We present maps of several radio lobes that are nearly coincident with galaxies. We have not found any new and unambiguous cases of gravitational lensing. One radio lobe in particular, FOV J0743+1553, has two hot spots that could be multiple images produced by a z=0.19 spiral galaxy, but the lensing interpretation is problematic.
- ID:
- ivo://CDS.VizieR/J/AN/338/700
- Title:
- Flux densities for 290 blazars
- Short Name:
- J/AN/338/700
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of nine years of the blazar observing programme at the RATAN-600 radio telescope (2005-2014). The data were obtained at six frequency bands (1.1, 2.3, 4.8, 7.7, 11.2, 21.7GHz) for 290 blazars, mostly BL Lacs. In addition, we used data at 37GHz obtained quasi-simultaneously with the Metsahovi radio observatory for some sources. For each source NVSS name (RA (hhmmss) and DEC (ddmmss) for the J2000.0 epoch), and flux densities at seven frequencies are presented (1.1-37GHz).
- ID:
- ivo://CDS.VizieR/VIII/57
- Title:
- Fluxes of Faint Radio Sources at 2.7/4.75 GHz
- Short Name:
- VIII/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This table is a compilation of revised 4.75 GHz and 2.695 GHz flux densities and corresponding spectral indices at epoch 1986.2 of a catalog of 239 sources, which has previously been published by Forkert and Altschuler, (1987A&AS...70...77F). It comprises 209 sources (marked 'A'), forming a complete, flux density limited sample above 50 mJy at 4.76 GHz in 1981.9 (Altschuler, 1986A&AS...65..267A), and 30 sources (marked 'a') below this limit, but with 5.0 GHz flux densities from 1971.0 (Davis, 1971AJ.....76..980D). The catalogue covers a narrow strip of the sky around declination of 33 degrees. The flux densities were calibrated with 3C286 on the scale of Kellermann, Pauliny-Toth and Williams (1969ApJ...157....1K). After publication of the catalog a statistical analysis for flux density variability in the data has been performed (Forkert, 1990), using 6cm flux density measurements of Davis (1971AJ.....76..980D) and Altschuler (1986A&AS...65..267A) and the 2.695 GHz flux densities of Pauliny-Toth et al. (1974A&A....35..421P), the details and results of which are going to be published elsewhere (Altschuler & Forkert, in preparation). For the purposes of this analysis it has become necessary to obtain more individual error estimates of the 1986.2 data, not dominated by the effect of overall scale errors. This revision for some of the sources also led to slightly different flux densities from those previously published. The variability study proved the flux density errors to represent the individual 1-sigma uncertainties, WITHOUT the effect of overall scale errors. From the aforementioned comparison with other measurements scale errors of ~1% at 2.695 GHz and ~3% at 4.75 GHz seem likely.
- ID:
- ivo://CDS.VizieR/J/A+A/609/A68
- Title:
- Full-Stokes polarimetry of 5 radio sources
- Short Name:
- J/A+A/609/A68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis pipeline that enables the recovery of reliable information for all four Stokes parameters with high accuracy. Its novelty relies on the effective treatment of the instrumental effects even before the computation of the Stokes parameters, contrary to conventionally used methods such as that based on the Mueller matrix. For instance, instrumental linear polarization is corrected across the whole telescope beam and significant Stokes Q and U can be recovered even when the recorded signals are severely corrupted by instrumental effects. The accuracy we reach in terms of polarization degree is of the order of 0.1-0.2%. The polarization angles are determined with an accuracy of almost 1{def}. The presented methodology was applied to recover the linear and circular polarization of around 150 active galactic nuclei, which were monitored between July 2010 and April 2016 with the Effelsberg 100-m telescope at 4.85GHz and 8.35GHz with a median cadence of 1.2 months. The polarized emission of the Moon was used to calibrate the polarization angle measurements. Our analysis showed a small system-induced rotation of about 1{deg} at both observing frequencies. Over the examined period, five sources have significant and stable linear polarization; three sources remain constantly linearly unpolarized; and a total of 11 sources have stable circular polarization degree m_c_, four of them with non-zero m_c_. We also identify eight sources that maintain a stable polarization angle. All this is provided to the community for future polarization observations reference. We finally show that our analysis method is conceptually different from those traditionally used and performs better than the Mueller matrix method. Although it has been developed for a system equipped with circularly polarized feeds, it can easily be generalized to systems with linearly polarized feeds as well.
- ID:
- ivo://CDS.VizieR/J/ApJS/118/201
- Title:
- Galactic Center 6 and 20cm survey
- Short Name:
- J/ApJS/118/201
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the VLA to survey 10 fields at 20 cm (1658MHz) and 11 fields at 6 cm (5GHz) that are between 7' and 137' from SgrA*. Our objective was to identify extragalactic sources and measure their scattering diameters so as to constrain the GC-scattering region separation. In order to find sources within these fields, we have employed pdfCLEAN, a source detection algorithm in which sources are identified in an image by comparing the intensity histogram of the image to that expected from a noise-only image. We found over 100 sources, with the faintest sources being approximately 3 mJy. The average number of sources per field is approximately 10, though fields close to SgrA* tend to contain fewer sources. A number of Galactic sources are included in our source catalog. The double-lobed source 1LC 359.872+0.178, potentially an X-ray quiet version of 1E 1740.7-2942, a shell-like structure with a central point source, and a possible radio transient, are discussed in the paper.
- ID:
- ivo://CDS.VizieR/J/ApJ/738/27
- Title:
- Galactic HII regions RRL and continuum data
- Short Name:
- J/ApJ/738/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The distribution of metals in the Galaxy provides important information about galaxy formation and evolution. HII regions are the most luminous objects in the Milky Way at mid-infrared to radio wavelengths and can be seen across the entire Galactic disk. We used the National Radio Astronomy Observatory (NRAO) Green Bank Telescope to measure radio recombination line (RRL) and continuum emission in 81 Galactic HII regions. We calculated LTE electron temperatures using these data. In thermal equilibrium metal abundances are expected to set the nebular electron temperature with high abundances producing low temperatures. Our HII region distribution covers a large range of Galactocentric radius (5-22kpc) and samples the Galactic azimuth range 330-60{deg}. Using our highest quality data (72 objects) we derived an O/H Galactocentric radial gradient of -0.0383+/-0.0074dex/kpc. Combining these data with a similar survey made with the NRAO 140 Foot telescope we get a radial gradient of -0.0446+/-0.0049dex/kpc for this larger sample of 133 nebulae.
80. Galactic Worms
- ID:
- ivo://CDS.VizieR/J/ApJ/390/108
- Title:
- Galactic Worms
- Short Name:
- J/ApJ/390/108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalog of candidates for the Galactic Worms that are possibly the walls surrounding the superbubbles is compiled; 118 isolated structures that appear both in HI and in IR (60 and 100{mu}m). 52 are possibly associated with HII regions. It is found that the 100-{mu}m emissivity increases systematically toward the Galactic interior, which is consistent with the increase of the general interstellar radiation field. The 100-{mu}m emissivity of the structures associated with the HII regions is larger than that of the structures without associated HII regions. The 60-100{mu}m ratio is large, 0.28+/-0.03, which may indicate that the grains associated with the atomic gas have a relatively large population of small grains. 35 structures appear in the 408MHz continuum. The IR and the radio continuum properties suggest that the 408MHz continuum emission in those structures is very likely thermal. The implications of these results on the ionization of gas far from the Galactic plane are discussed.