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2251. VLBA calibrator survey: VCS1 catalog
ID:
ivo://CDS.VizieR/J/ApJS/141/13
Title:
VLBA calibrator survey: VCS1 catalog
Short Name:
J/ApJS/141/13
Date:
21 Oct 2021
Publisher:
CDS
Description:
A catalog containing milli-arcsecond-accurate positions of 1332 extragalactic radio sources distributed over the northern sky is presented - the Very Long Baseline Array Calibrator Survey (VCS1). The positions have been derived from astrometric analysis of dual-frequency 2.3 and 8.4 GHz VLBA snapshot observations; in a majority of cases, images of the sources are also available. These radio sources are suitable for use in geodetic and astrometric experiments, and as phase-reference calibrators in high-sensitivity astronomical imaging. The VCS1 is the largest high-resolution radio survey ever undertaken and triples the number of sources available to the radio astronomy community for VLBI applications. In addition to the astrometric role, this survey can be used in active galactic nuclei, Galactic, gravitational lens, and cosmological studies.
2252. VLBA imaging and polarimetry survey at 5GHz
ID:
ivo://CDS.VizieR/J/ApJ/658/203
Title:
VLBA imaging and polarimetry survey at 5GHz
Short Name:
J/ApJ/658/203
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first results of the VLBA Imaging and Polarimetry Survey (VIPS), a 5GHz VLBI survey of 1119 sources with flat radio spectra. Through automated data reduction and imaging routines, we have produced publicly available I, Q, and U images and have detected polarized flux density from 37% of the sources. We have also developed an algorithm to use each source's I image to automatically classify it as a pointlike source, a core jet, a compact symmetric object (CSO) candidate, or a complex source. Using data from the Sloan Digital Sky Survey (SDSS), we have found no significant trend between optical flux and 5 GHz flux density for any of the source categories.
2253. VLBI Ecliptic Plane Survey: VEPS-1
ID:
ivo://CDS.VizieR/J/ApJS/230/13
Title:
VLBI Ecliptic Plane Survey: VEPS-1
Short Name:
J/ApJS/230/13
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present here the results of the first part of the VLBI Ecliptic Plane Survey (VEPS) program. The goal of the program is to find all compact sources within 7.5{deg} of the ecliptic plane that are suitable as calibrators for anticipated phase referencing observations of spacecraft, and determine their positions with accuracy at the 1.5 nrad level. We run the program in two modes: search and refine. In the search mode, a complete sample of all sources brighter than 50mJy at 5GHz listed in the Parkes-MIT-NRAO and Green Bank 6cm (GB6) catalogs, except those previously detected with VLBI, is observed. In the refining mode, the positions of all ecliptic plane sources, including those found in the search mode, are improved. By 2016 October, thirteen 24hr sessions that targeted all sources brighter than 100mJy have been observed and analyzed. Among 3320 observed target sources, 555 objects have been detected. We also conducted a number of follow-up VLBI experiments in the refining mode and improved the positions of 249 ecliptic plane sources.
2254. VLT-FLAMES Tarantula Survey
ID:
ivo://CDS.VizieR/J/A+A/530/A108
Title:
VLT-FLAMES Tarantula Survey
Short Name:
J/A+A/530/A108
Date:
21 Oct 2021
Publisher:
CDS
Description:
The VLT-FLAMES Tarantula Survey (VFTS) is an ESO Large Programme that has obtained multi-epoch optical spectroscopy of over 800 massive stars in the 30 Doradus region of the Large Magellanic Cloud (LMC). Here we introduce our scientific motivations and give an overview of the survey targets, including optical and near-infrared photometry and comprehensive details of the data reduction. One of the principal objectives was to detect massive binary systems via variations in their radial velocities, thus shaping the multi-epoch observing strategy. Spectral classifications are given for the massive emission-line stars observed by the survey, including the discovery of a new Wolf-Rayet star (VFTS 682, classified as WN5h), 2' to the northeast of R136. To illustrate the diversity of objects encompassed by the survey, we investigate the spectral properties of sixteen targets identified by Gruendl & Chu (2009, Cat. J/ApJS/184/172) from Spitzer photometry as candidate young stellar objects or stars with notable mid-infrared excesses. Detailed spectral classification and quantitative analysis of the O- and B-type stars in the VFTS sample, paying particular attention to the effects of rotational mixing and binarity, will be presented in a series of future articles to address fundamental questions in both stellar and cluster evolution.
2255. VLT ISAAC Ks Observations of the Southern Hubble Ultradeep Field
ID:
ivo://nasa.heasarc/skyview/hudfisaac
Title:
VLT ISAAC Ks Observations of the Southern Hubble Ultradeep Field
Short Name:
HUDFISAAC
Date:
07 Mar 2025
Publisher:
NASA/GSFC HEASARC
Description:
A very deep Ks observation of the Hubble Ultradeep Field. This observation is approximately 0.6 magnitudes deeper than the GOODS ISAAC Ks image but covers only small fraction of the area. Provenance: Data downloaded from VLT archive. This is a service of NASA HEASARC.
2256. VLT LBG Redshift Survey. III.
ID:
ivo://CDS.VizieR/J/MNRAS/430/425
Title:
VLT LBG Redshift Survey. III.
Short Name:
J/MNRAS/430/425
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalogue of 2135 galaxy redshifts from the VLT LBG Redshift Survey (VLRS), a spectroscopic survey of z~3 galaxies in wide fields centred on background quasi-stellar objects. We have used deep optical imaging to select galaxies via the Lyman-break technique. Spectroscopy of the Lyman-break galaxies (LBGs) was then made using the Very Large Telescope (VLT) Visible Multi-Object Spectrograph (VIMOS) instrument, giving a mean redshift of z=2.79. We analyse the clustering properties of the VLRS sample and also of the VLRS sample combined with the smaller area Keck-based survey of Steidel et al. (2003, Cat. J/ApJ/592/728).
2257. VLT spectroscopic survey of RX J0152.7-1357
ID:
ivo://CDS.VizieR/J/A+A/432/381
Title:
VLT spectroscopic survey of RX J0152.7-1357
Short Name:
J/A+A/432/381
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of an extensive spectroscopic survey of RX J0152.7-1357, one of the most massive distant clusters of galaxies known. Multi-object spectroscopy, carried out with FORS1 and FORS2 on the ESO Very Large Telescope (VLT), has allowed us to measure more than 200 redshifts in the cluster field and to confirm 102 galaxies as cluster members. The mean redshift of the cluster is z=0.837+/-0.001 and we estimate the velocity dispersion of the overall cluster galaxy distribution to be ~1600km/s.
2258. VLT Survey Telescope ATLAS
ID:
ivo://CDS.VizieR/II/350
Title:
VLT Survey Telescope ATLAS
Short Name:
II/350
Date:
21 Oct 2021
Publisher:
CDS
Description:
The VLT Survey Telescope ATLAS survey is an optical ugriz survey aiming to cover ~4700deg^2^ of the southern sky to similar depths as the Sloan Digital Sky Survey (SDSS). From reduced images and object catalogues provided by the Cambridge Astronomical Surveys Unit, we first find that the median seeing ranges from 0.8-arcsec FWHM (full width at half-maximum) in i to 1.0-arcsec in u, significantly better than the 1.2-1.5arcsec seeing for SDSS. The 5{sigma} mag limit for stellar sources is r_AB_=22.7 and in all bands these limits are at least as faint as SDSS. SDSS and ATLAS are more equivalent for galaxy photometry except in the z band where ATLAS has significantly higher throughput. We have improved the original ESO magnitude zero-points by comparing m<16 star magnitudes with the AAVSO Photometric All-Sky Survey in gri, also extrapolating into u and z, resulting in zero-points accurate to ~+/-0.02mag. We finally compare star and galaxy number counts in a 250deg^2^ area with SDSS and other count data and find good agreement. ATLAS data products can be retrieved from the ESO Science Archive, while support for survey science analyses is provided by the OmegaCAM Science Archive, operated by the Wide-Field Astronomy Unit in Edinburgh.
2259. VLT/VIMOS spectroscopy in GOODS-South field
ID:
ivo://CDS.VizieR/J/A+A/512/A12
Title:
VLT/VIMOS spectroscopy in GOODS-South field
Short Name:
J/A+A/512/A12
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the full data set of the VIsible Multi-Object Spectrograph (VIMOS) spectroscopic campaign of the ESO/GOODS program in the Chandra Deep Field South (CDFS), which complements the FORS2 ESO/GOODS spectroscopic campaign. The ESO/GOODS spectroscopic programs are aimed at reaching signal-to-noise ratios adequate to measure redshifts for galaxies with AB magnitudes in the range ~24-25 in the B and R band using VIMOS, and in the z band using FORS2.
2260. VMC XXVII. Young stellar structures in the LMC
ID:
ivo://CDS.VizieR/J/ApJ/849/149
Title:
VMC XXVII. Young stellar structures in the LMC
Short Name:
J/ApJ/849/149
Date:
21 Oct 2021
Publisher:
CDS
Description:
Star formation is a hierarchical process, forming young stellar structures of star clusters, associations, and complexes over a wide range of scales. The star-forming complex in the bar region of the Large Magellanic Cloud is investigated with upper main-sequence stars observed by the VISTA Survey of the Magellanic Clouds. The upper main-sequence stars exhibit highly nonuniform distributions. Young stellar structures inside the complex are identified from the stellar density map as density enhancements of different significance levels. We find that these structures are hierarchically organized such that larger, lower-density structures contain one or several smaller, higher- density ones. They follow power-law size and mass distributions, as well as a lognormal surface density distribution. All these results support a scenario of hierarchical star formation regulated by turbulence. The temporal evolution of young stellar structures is explored by using subsamples of upper main-sequence stars with different magnitude and age ranges. While the youngest subsample, with a median age of log({tau}/yr)=7.2, contains the most substructure, progressively older ones are less and less substructured. The oldest subsample, with a median age of log({tau}/yr)=8.0, is almost indistinguishable from a uniform distribution on spatial scales of 30-300pc, suggesting that the young stellar structures are completely dispersed on a timescale of ~100Myr. These results are consistent with the characteristics of the 30 Doradus complex and the entire Large Magellanic Cloud, suggesting no significant environmental effects. We further point out that the fractal dimension may be method dependent for stellar samples with significant age spreads.

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