- ID:
- ivo://CDS.VizieR/J/AJ/136/580
- Title:
- Sixth VLBA calibrator survey: VCS6
- Short Name:
- J/AJ/136/580
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents the sixth part of the Very Long Baseline Array (VLBA) Calibrator Survey. It contains the positions and maps of 264 sources of which 169 were not previously observed with very long baseline interferometry. This survey, based on two 24h VLBA observing sessions, was focused on (1) improving positions of 95 sources from previous VLBA Calibrator Surveys that were observed either with very large a priori position errors or were observed not long enough to get reliable positions and (2) observing remaining new flat-spectrum sources with predicted correlated flux density in the range 100-200mJy that were not observed in previous surveys. Source positions were derived from astrometric analysis of group delays determined at the 2.3 and 8.6GHz frequency bands using the Calc/Solve software package. The VCS6 catalog of source positions, plots of correlated flux density versus projected baseline length, contour plots and fits files of naturally weighted CLEAN images, as well as calibrated visibility function files, are available on the Web at http://vlbi.gsfc.nasa.gov/vcs6.
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- ID:
- ivo://CDS.VizieR/J/ApJS/74/181
- Title:
- Small-diameter radiosources catalogue
- Short Name:
- J/ApJS/74/181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A survey of the Galactic plane in the longitude range -20deg=<l<=120deg for Galactic latitudes |b|=<0.8deg has been carried out at 1400MHz using the VLA in the B configuration. We present here a catalog of the 1992 discrete sources detected in this survey which is ~75% complete to a limiting peak flux density of 25mJy for sources smaller than ~20" in diameter, although sources as faint as 8mJy and as large as 90" are also included. The catalog includes for each entry a position accurate to ~<3", peak and integrated flux densities, source extent, and information on counterparts both from earlier radio surveys of the plane (for which a comprehensive bibliography is included) and from the IRAS point source catalog. An extensive analysis of the integrity and completeness of the survey is presented here: in separate publications, we discuss the source content of the survey as derived from statistical analysis of the spatial distribution of the sources and from radio, optical and infrared follow up observations .
- ID:
- ivo://CDS.VizieR/J/A+A/561/A55
- Title:
- Small-diameter sources in Sino-German 6cm survey
- Short Name:
- J/A+A/561/A55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out the Sino-German 6cm polarisation survey of the Galactic plane at 6cm in total and polarised intensity using the Urumqi 25-m telescope of Xinjiang (formerly Urumqi) Astronomical Observatory, Chinese Academy of Sciences. The angular resolution is 9.5-arcmin. The surveyed area covers 10{deg} to 230{deg} in Galactic longitude and absolute Galactic latitudes of up to 5{deg}. The measured rms-noise is about 6.1 mJy/beam area for total intensities and 3.05mJy/beam area for polarised intensities. The survey maps are accessible from http://zmtt.bao.ac.cn/6cm/ .
- ID:
- ivo://CDS.VizieR/J/A+A/587/A47
- Title:
- SMA 1.3mm image of OMC 1 North
- Short Name:
- J/A+A/587/A47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The filamentary structure of molecular clouds may set important constraints on the mass distribution of stars forming within them. It is therefore important to understand which physical mechanism dominates filamentary cloud fragmentation and core formation. Orion A is the nearest giant molecular cloud, and its so-called S-shaped filament is a very active star-forming region that is a good target for such a study. We have recently reported on the collapse and fragmentation properties of the northernmost part of this structure, located ~2.4pc north of Orion KL - Orion Molecular Cloud (OMC) 3. As part of our project to study the S-shaped filament, we analyze the fragmentation properties of the northern OMC 1 filament (located <~0.3pc north of Orion KL). This filament is a dense structure previously identified by JCMT/SCUBA submillimeter continuum and VLA NH_3_ observations and was shown to have fragmented into clumps. Our aim is to search for cores and young protostars embedded within OMC 1n and to study how the filament is fragmenting to form them. We observed OMC 1North (hereafter OMC 1n) with the Submillimeter Array (SMA) at 1.3mm and report on our analysis of the continuum data.
- ID:
- ivo://CDS.VizieR/J/A+AS/121/321
- Title:
- SMC catalogue of radiosources
- Short Name:
- J/A+AS/121/321
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present catalogues of radio sources in the Small Magellanic Cloud from observations with the Parkes radio telescope at 1.42, 2.45, 4.75 and 8.55GHz, and an additional catalogue from the Parkes-MIT-NRAO survey at 4.85GHz. A total of 224 sources were detected at at least one of these frequencies, 60 of which are reported here for the first time as radio sources. We compare positions and flux densities of these sources with previously published results and find no significant positional displacement or flux discrepancies.
- ID:
- ivo://CDS.VizieR/J/other/Ser/183.103
- Title:
- SMC observations at 13, 20 and 36cm
- Short Name:
- J/other/Ser/183.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalogue of radio-continuum sources in the field of the Small Magellanic Cloud (SMC). This catalogue contains sources previously not found in 2370MHz (λ=13cm) with sources found at 1400MHz (λ=20cm) and 843MHz (λ=36cm). 45 sources have been detected at 13cm, with 1560 sources at 20cm created from new high sensitivity and resolution radio-continuum images of the SMC at 20cm from paper I (Wong et al., <A HREF="http://simbad.cds.unistra.fr/simbad/sim-ref?bibcode=2011SerAJ.182...43W%202011SerAJ.182...43W">2011SerAJ.182...43W 2011SerAJ.182...43W</A>). We also created a 36cm catalogue to which we listed 1689 radio-continuum sources.
- ID:
- ivo://CDS.VizieR/J/MNRAS/431/2453
- Title:
- SN1996cr radio observations
- Short Name:
- J/MNRAS/431/2453
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present newly reduced archival radio observations of SN 1996cr in the Circinus Galaxy from the Australia Telescope Compact Array and the Molonglo Observatory Synthesis Telescope, and attempt to model its radio light curves using recent hydrodynamical simulations of the interaction between the supernova (SN) ejecta and the circumstellar material (CSM) at X-ray wavelengths. The radio data within the first 1000d show clear signs of free-free absorption (FFA), which decreases gradually and is minimal above 1.4GHz after day ~3000. Constraints on the FFA optical depth provide estimates of the CSM free electron density, which allows insight into the ionization of SN 1996cr's CSM and offers a test on the density distribution adopted by the hydrodynamical simulation. The intrinsic spectral index of the radiation shows evidence for spectral flattening, which is characterized by {alpha}=0.852+/-0.002 at day 3000 and a decay rate of {Delta}{alpha}=-0.014+/-0.001yr^-1^. The striking similarity in the spectral flattening of SN 1987A, SN 1993J and SN 1996cr suggests this may be a relatively common feature of SNe/CSM shocks. We adopt this spectral index variation to model the synchrotron radio emission of the shock, and consider several scalings that relate the parameters of the hydrodynamical simulation to the magnetic field and electron distribution. The simulated light curves match the large-scale features of the observed light curves, but fail to match certain tightly constraining sections. This suggests that simple energy density scalings may not be able to account for the complexities of the true physical processes at work, or alternatively, that the parameters of the simulation require modification in order to accurately represent the surroundings of SN 1996cr.
- ID:
- ivo://CDS.VizieR/J/A+A/593/A18
- Title:
- SN 2008iz 4.8 and 8.4GHz images
- Short Name:
- J/A+A/593/A18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on multi-frequency Very Large Array (VLA) and Very Long Baseline Interferometry (VLBI) radio observations for a monitoring campaign of supernova SN 2008iz in the nearby irregular galaxy M82.
- ID:
- ivo://CDS.VizieR/J/A+A/587/A71
- Title:
- SNR G11.0-0.0 1.4GHz radio continuum image
- Short Name:
- J/A+A/587/A71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The main goal of this paper is to provide new insights on the origin of the observable flux of {gamma} rays from HESS J1809-193 using new high-quality observations in the radio domain. We used the Expanded Very Large Array (now known as the Karl G. Jansky Very large Array, JVLA) to produce a deep full-synthesis imaging at 1.4GHz of the vicinity of PSR J1809-1917. These data were used in conjunction with 12CO observations from the James Clerk Maxwell Telescope in the transition line J=3-2 and atomic hydrogen data from the Southern Galactic Plane Survey to investigate the properties of the interstellar medium in the direction of the source HESS J1809-193.
- ID:
- ivo://CDS.VizieR/J/A+A/642/A136
- Title:
- Sources detected at 325 and 610 MHz in Cygnus
- Short Name:
- J/A+A/642/A136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations at the radio continuum band below the gigahertz band are key when the nature and properties of non-thermal sources are investigated because their radio radiation is strongest at these frequencies. The low radio frequency range is therefore the best to spot possible counterparts to very high-energy (VHE) sources: relativistic particles of the same population are likely to be involved in radio and high-energy radiation processes. Some of these counterparts to VHE sources can be stellar sources. The Cygnus region in the northern sky is one of the richest in this type of sources that are potential counterparts to VHEsources. We surveyed the central ~15 sq deg of the Cygnus constellation at the 325 and 610MHz bands with angular resolutions and sensitivities of 10" and 6", and 0.5 and 0.2mJy/beam, respectively. The data were collected during 172 hours in 2013-2017, using the Giant Metrewave Radio Telescope (GMRT) with 32MHz bandwidth, and were calibrated using the SPAM routines. The source extraction was carried out with the PyBDSF tool,followed by verification through visual inspection of every putative catalog candidate source in order to determine its reliability. In this first paper we present the catalog of sources, consisting of 1048 sources at 325MHz and 2796 sources at 610MHz. By cross-matching the sources from both frequencies with the objects of the SIMBAD database, we found possible counterparts for 143 of them. Most of the sources from the 325MHz catalog (993) were detected at the 610MHz band, and their spectral index alpha was computed adopting S(nu){prop.to}nu^alpha^. The maximum of the spectral index distribution is at alpha=-1, which is characteristic of non-thermal emitters and might indicate an extragalactic population.
