- ID:
- ivo://CDS.VizieR/VIII/37
- Title:
- The Third Bologna Survey (B3)
- Short Name:
- VIII/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue contains the first section of a sky survey performed at 408MHz with the 'Northern Cross' Radiotelescope. It contains about 13.000 radiosources. Although sources down to about 70mJy were measured, only sources brighter than 0.10Jy are retained in the catalogue. According to our estimate of confusion errors, this corresponds to a detection threshold of about 5{sigma}. The list is meant to include all the sources with a measured flux S>0.10Jy, in the sky area included between the declinations +37{deg}15' and +47{deg}37', epoch 1978.0. A number of zones however are affected by interferences, malfunctions, etc. The principal one is centered about the radiosource Cyg A, which is itself in the map, but not in the catalogue. The zone between RA 19h30m to 20h30m is entirely lacking, due to strong confusion. In the zone from 19h00m to 19h30m and from 20h30m to 21h00m, only sources brighter than 0.75Jy are listed, and to this level the catalogue is espected to be complete. For detailed discussion of the completeness of the catalogue see the original publication cited above.
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- ID:
- ivo://CDS.VizieR/J/A+A/644/A159
- Title:
- The third realization of the ICRF, ICRF3
- Short Name:
- J/A+A/644/A159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new realization of the International Celestial Reference Frame (ICRF) is presented based on the work achieved by a working group of the International Astronomical Union (IAU) mandated for this purpose. This new realization follows the initial realization of theICRF completed in 1997 and its successor, ICRF2, adopted as a replacement in 2009. The new frame, referred to as ICRF3, is based on nearly 40 years of data acquired by very long baseline interferometry at the standard geodetic and astrometric radio frequencies (8.4 and 2.3GHz), supplemented with data collected at higher radio frequencies (24GHz and dual-frequency 32 and 8.4GHz) over the past 15 years. State-of-the-art astronomical and geophysical modeling has been used to analyze these data and derive source positions. The modeling integrates, for the first time, the effect of the galactocentric acceleration of the solar system (directly estimated from the data) which, if not considered, induces significant deformation of the frame due to the data span. The new frame includes positions at 8.4GHz for 4536 extragalactic sources. Of these, 303 sources, uniformly distributed on the sky, are identified as "defining sources" and as such serve to define the axes of the frame. Positions at 8.4GHz are supplemented with positions at 24GHz for 824 sources and at 32GHz for 678 sources. In all, ICRF3 comprises 4588 sources, with three-frequency positions available for 600 of these. Source positions have been determined independently at each of the frequencies in order to preserve the underlying astrophysical content behind such positions. They are reported for epoch 2015.0 and must be propagated for observations at other epochs for the most accurate needs, accounting for the acceleration toward the Galactic center, which results in a dipolar proper motion field of amplitude 0.0058 milliarcsecond/yr (mas/yr). The frame is aligned onto the International Celestial Reference System to within the accuracy of ICRF2 and shows a median positional uncertainty of about 0.1mas in right ascension and 0.2 mas in declination, with a noise floor of 0.03mas in the individual source coordinates. A subset of 500 sources is found to have extremely accurate positions, in the range of 0.03 to 0.06mas, at the traditional 8.4GHz frequency. Comparing ICRF3 with the recently released Gaia Celestial Reference Frame 2 in the optical domain, there is no evidence for deformations larger than 0.03 mas between the two frames, in agreement with the ICRF3 noise level. Significant positional offsets between the three ICRF3 frequencies are detected for about 5% of the sources.Moreover, a notable fraction (22%) of the sources shows optical and radio positions that are significantly offset. There are indications that these positional offsets may be the manifestation of extended source structures. This third realization of the ICRF was adopted by the IAU at its 30th General Assembly in August 2018 and replaced the previous realization, ICRF2, on January 1, 2019.
- ID:
- ivo://CDS.VizieR/J/A+A/642/L13
- Title:
- The Toothbrush relic 14.25GHz image
- Short Name:
- J/A+A/642/L13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radio relics trace shock fronts generated in the intracluster medium (ICM) during cluster mergers. The particle acceleration mechanism at the shock fronts is not yet completely understood. We observed the Toothbrush relic with the Effelsberg and Sardinia Radio Telescope at 14.25GHz and 18.6GHz, respectively. Unlike previously claimed, the integrated spectrum of the relic closely follows a power law over almost three orders of magnitude in frequency, with a spectral index of {alpha}_58MHz_^18.6GHz^=-1.16+/-0.03. Our finding is consistent with a power-law injection spectrum, as predicted by diffusive shock acceleration theory. The result suggests that there is only little magnetic field strength evolution downstream of the shock. From the lack of spectral steepening, we find that either the Sunyaev-Zeldovich decrement produced by the pressure jump is less extended than ~600kpc along the line of sight or, conversely, that the relic is located far behind in the cluster. For the first time, we detect linearly polarized emission from the "brush" at 18.6GHz. Compared to 8.3GHz, the degree of polarization across the brush increases at 18.6GHz, suggesting a strong Faraday depolarization toward lower frequencies. The observed depolarization is consistent with an intervening magnetized screen that arises from the dense ICM containing turbulent magnetic fields. The depolarization, corresponding to a standard deviation of the rotation measures as high as {sigma}_RM_=212+/-23rad/m^2^, suggests that the brush is located in or behind the ICM. Our findings indicate that the Toothbrush relic can be consistently explained by the standard scenario for relic formation.
- ID:
- ivo://CDS.VizieR/J/A+A/434/201
- Title:
- The 35um absorption line towards 1612MHz masers
- Short Name:
- J/A+A/434/201
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 1612MHz hydroxyl maser in circumstellar envelopes has long been thought to be pumped by 34.6{mu}m photons. Only recently, the Infrared Space Observatory has made possible spectroscopic observations which enable the direct confirmation of this pumping mechanism in a few cases. To look for the presence of this pumping line, we have searched the Infrared Space Observatory Data Archive and found 178 spectra with data around 34.6{mu}m for 87 galactic 1612MHz masers.
- ID:
- ivo://CDS.VizieR/VIII/80
- Title:
- The UTR-2 Very Low-Frequency Sky Survey Data
- Short Name:
- VIII/80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of the very-low frequency (16.7MHz) survey of discrete sources made with the UTR-2 radio telescope is presented. The survey concerns the declination zones -13{deg} to -2{deg}, 0{deg} to 20{deg}, 30{deg} to 40{deg}, and 41{deg} to 60{deg}. The UTR-2 radio source catalogue contains an estimate of the coordinates and flux densities of 1819 sources measured at a number of the lowest frequencies used in contemporary radio astronomy within the range from 10 to 25 MHz. The catalogue is made of two parts: mean.dat: the averaged values of the coordinates and the corresponding errors, the source flux-density at the middle UTR-2 frequency 16.7 MHz as obtained from measured spectrum of the source at all UTR-2 frequencies and its error, the value of measured low-frequency spectral index with respect to which the estimate of has been obtained, the parameter W characterizing the integral reliability of the obtained source estimates and the corresponding object name from higher-frequency radio survey provided the source has been identified. To indicate the integral readability of the source parameters obtained we used the symbols A, B and C. These reliability estimates take into account the total number of measurements, coordinate scatter, number of frequencies and hour-angle settings at which the source parameters have been evaluated. The highly reliable observation results have been marked with symbol A . The sources whose parameters can be used without an additional analysis are marked with B and sources whose parameters are to be used with care have been marked with C. data.dat: this file contains the experimental estimates of the source coordinates and flux densities as well as their errors at each operating frequency of the UTR-2 in the order of their increasing; the total number (N) of successive observations according to which the estimates were obtained and the number of different hour-angle settings (NRA) of the reception pattern at which the source was observed. In cases when the observations did not allow us to obtain a reliable estimates of a source flux density the catalogue contains only their upper limits which are not accompanied by errors. The approximated values of as well as low-frequency spectral indices are presented only for those sources which have flux density estimates obtained at not less than three different UTR-2 frequencies.
- ID:
- ivo://CDS.VizieR/VIII/41
- Title:
- The UTR-2 Very Low-Frequency Sky Survey Data
- Short Name:
- VIII/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of the very-low frequency (16.7MHz) survey of discrete sources made with the UTR-2 radio telescope is presented. The survey concerns the declination zones -13{deg} to -2{deg}, 0{deg} to 20{deg}, and 41{deg} to 60{deg}. The UTR-2 radio source catalogue contains an estimate of the coordinates and flux densities of 1819 sources measured at a number of the lowest frequencies used in contemporary radio astronomy within the range from 10 to 25 MHz. The catalogue is made of two parts: mean.dat: the averaged values of the coordinates and the corresponding errors, the source flux-density at the middle UTR-2 frequency 16.7 MHz as obtained from measured spectrum of the source at all UTR-2 frequencies and its error, the value of measured low-frequency spectral index with respect to which the estimate of has been obtained, the parameter W characterizing the integral reliability of the obtained source estimates and the corresponding object name from higher-frequency radio survey provided the source has been identified. To indicate the integral readability of the source parameters obtained we used the symbols A, B and C. These reliability estimates take into account the total number of measurements, coordinate scatter, number of frequencies and hour-angle settings at which the source parameters have been evaluated. The highly reliable observation results have been marked with symbol A . The sources whose parameters can be used without an additional analysis are marked with B and sources whose parameters are to be used with care have been marked with C. data.dat: this file contains the experimental estimates of the source coordinates and flux densities as well as their errors at each operating frequency of the UTR-2 in the order of their increasing; the total number (N) of successive observations according to which the estimates were obtained and the number of different hour-angle settings (NRA) of the reception pattern at which the source was observed. In cases when the observations did not allow us to obtain a reliable estimates of a source flux density the catalogue contains only their upper limits which are not accompanied by errors. The approximated values of as well as low-frequency spectral indices are presented only for those sources which have flux density estimates obtained at not less than three different UTR-2 frequencies.
1727. The VLA-COSMOS survey
- ID:
- ivo://CDS.VizieR/J/AJ/128/1974
- Title:
- The VLA-COSMOS survey
- Short Name:
- J/AJ/128/1974
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 246 radio sources found in the central 1{deg} of the COSMOS field at 1.4GHz. The VLA pilot project data have a resolution of 1.9"x1.6" and an rms noise limit of ~25-100{mu}Jy/beam covering 0.837{deg}^2. About 20 radio sources are clearly extended, and most of them appear to be double-lobed radio galaxies. We find evidence for a cluster of seven radio galaxies with an extent of ~10' southeast of the COSMOS field center.
- ID:
- ivo://CDS.VizieR/J/ApJS/188/384
- Title:
- The VLA-COSMOS survey. IV.
- Short Name:
- J/ApJS/188/384
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the context of the VLA-COSMOS Deep project, additional VLA A array observations at 1.4GHz were obtained for the central degree of the COSMOS field and combined with the existing data from the VLA-COSMOS Large project. A newly constructed Deep mosaic with a resolution of 2.5" was used to search for sources down to 4{sigma} with 1{sigma}~12uJy/beam in the central 50'x50'. This new catalog is combined with the catalog from the Large project (obtained at 1.5"x1.4" resolution) to construct a new Joint catalog. All sources listed in the new Joint catalog have peak flux densities of >=5{sigma} at 1.5" and/or 2.5" resolution to account for the fact that a significant fraction of sources at these low flux levels are expected to be slightly resolved at 1.5" resolution. All properties listed in the Joint catalog, such as peak flux density, integrated flux density, and source size, are determined in the 2.5" resolution Deep image. In addition, the Joint catalog contains 43 newly identified multi-component sources.
- ID:
- ivo://CDS.VizieR/J/MNRAS/443/2590
- Title:
- The VLA-COSMOS Survey. V. 324MHz
- Short Name:
- J/MNRAS/443/2590
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 90cm Very Large Array imaging of the COSMOS field, comprising a circular area of 3.14 square degrees at 8.0"x6.0" angular resolution with an average rms of 0.5mJy/beam. The extracted catalogue contains 182 sources (down to 5.5{sigma}), 30 of which are multicomponent sources. Using Monte Carlo artificial source simulations, we derive the completeness of the catalogue, and we show that our 90cm source counts agree very well with those from previous studies. Using X-ray, NUV-NIR and radio COSMOS data to investigate the population mix of our 90cm radio sample, we find that our sample is dominated by active galactic nuclei. The average 90-20cm spectral index (S_{nu}_{prop.to}{nu}^{alpha}^, where S_{nu}_ is the flux density at frequency {nu} and {alpha} the spectral index) of our 90cm selected sources is -0.70, with an interquartile range from -0.90 to -0.53. Only a few ultra-steep-spectrum sources are present in our sample, consistent with results in the literature for similar fields. Our data do not show clear steepening of the spectral index with redshift. Nevertheless, our sample suggests that sources with spectral indices steeper than -1 all lie at z>~1, in agreement with the idea that ultra-steep-spectrum radio sources may trace intermediate-redshift galaxies (z>~1).
- ID:
- ivo://CDS.VizieR/VIII/79A
- Title:
- The VLA Low-frequency Sky Survey at 74MHz
- Short Name:
- VIII/79A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The VLA Low-Frequency Sky Survey (VLSS) is a 74MHz (4m) continuum survey covering the entire sky north of -30{deg} declination. Using the VLA in B- and BnA-configurations, we will map the entire survey region at a resolution of 80" and with an average rms noise of 0.1 Jy/beam. For a detailed description of the survey and its scientific motivations, please see the original proposal to the NRAO skeptical review committee. The VLSS is being made as a service to the astronomical community, and the principal data products are being released to the public as soon as they are produced and verified. Details and access to the images can be found at http://lwa.nrl.navy.mil/VLSS/
