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22761. Ultra-steep spectrum radiosources
ID:
ivo://CDS.VizieR/J/A+AS/108/79
Title:
Ultra-steep spectrum radiosources
Short Name:
J/A+AS/108/79
Date:
21 Oct 2021
Publisher:
CDS
Description:
Radio sources with ultra-steep spectra (USS; spectral index <~ -1.0) have been found to be excellent tracers of galaxies at redshifts z>~2. The samples are selected from the set of catalogues referenced below, in a range of frequencies from 38 to 408MHz; they are are fainter by a factor of three than the previously well-studied samples of USS sources from 4C. Snapshot observations of sources from these samples have been made with the VLA at 1.5arcsec resolution and are presented in the printed paper. The list of the sources (Appendix A of the paper) includes positions, flux densities and radio structures for a total number of 605 sources derived from these observations.
22762. Ultra-steep spectrum radio sources
ID:
ivo://CDS.VizieR/J/A+A/436/457
Title:
Ultra-steep spectrum radio sources
Short Name:
J/A+A/436/457
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of radio (VLA) and optical (ESO/La Silla) imaging of a sample of 52 radio sources having an ultra-steep radio spectrum with {alpha} mostly steeper than -1.1 at decimetre wavelengths (median {alpha}=-1.22). Radio-optical overlays are presented to an astrometric accuracy of ~1". For 41 of the sources, radio spectral indices are newly determined using unpublished observations made with the 100-m Effelsberg radio telescope. For 14 of the sources identified with relatively brighter optical counterparts, spectroscopic observations were also carried out at La Silla and their redshifts are found to lie in the range 0.4 to 2.6.
22763. Ultra steep spectrum radio sources catalog
ID:
ivo://CDS.VizieR/J/A+AS/143/303
Title:
Ultra steep spectrum radio sources catalog
Short Name:
J/A+AS/143/303
Date:
21 Oct 2021
Publisher:
CDS
Description:
The three tables contain the 669 Ultra Steep Spectrum sources from the 3 samples WN (WENSS-NVSS), TN (TEXAS-NVSS) and MP (MRC-PMN) (tables A.1, A.2 and A.3). For each source, the radio fluxes from the surveys and from VLA or ATCA observations are given, as well as coordinates, radio structure, angular size and position angle determined from the radio map indicated in the last column.
22764. Ultra-steep spectrum radio sources in SDSS
ID:
ivo://CDS.VizieR/J/MNRAS/406/197
Title:
Ultra-steep spectrum radio sources in SDSS
Short Name:
J/MNRAS/406/197
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyse optical and radio properties of radio galaxies detected in the Sloan Digital Sky Survey. The sample of radio sources is selected from the catalogue of Kimball & Ivezic (2008AJ....136..684K) with flux densities at 325, 1400 and 4850MHz, using Westerbork Northern Sky Survey, NRAO VLA Sky Survey and Green Bank 6cm radio surveys and from flux measurements at 74MHz taken from Very Large Array Low-Frequency Sky Survey (Cohen et al. 2006, Cat. VIII/79). We study radio galaxy spectral properties using radio colour-colour diagrams and find that our sample follows a single power law from 74 to 4850MHz.
22765. Ultraviolet Excess Galaxies
ID:
ivo://CDS.VizieR/VII/63
Title:
Ultraviolet Excess Galaxies
Short Name:
VII/63
Date:
21 Oct 2021
Publisher:
CDS
Description:
The catalog contains a list of 412 faint galaxies selected for their apparent ultraviolet excess. The galaxies were selected from a 3-color (UBV) plate taken with the Palomar 48-inch Schmidt telescope. The 14-inch-square plates cover an area of 30 square degrees centered on Kapteyn Selected Area 28. The catalog includes running numbers, coordinates, color codes, magnitude codes, morphologies, diameters, and notes. The catalogued galaxies were selected by eye from the Palomar Schmidt 3-color (UBV) plate PS24771, centered on Kapteyn Selexted Area 28 and taken by Usher under conditions of good seeing and transparency.
22766. Ultraviolet Extinction in the GALEX Bands. UVEXT
ID:
ivo://CDS.VizieR/J/ApJ/861/153
Title:
Ultraviolet Extinction in the GALEX Bands. UVEXT
Short Name:
J/ApJ/861/153
Date:
21 Oct 2021
Publisher:
CDS
Description:
Interstellar extinction in ultraviolet is the most severe in comparison with optical and infrared wavebands and a precise determination plays an important role in correctly recovering the ultraviolet brightness and colors of objects. By finding the observed bluest colors at the given effective temperature and metallicity range of dwarf stars, stellar intrinsic colors, C_B,V_^0^, C_NUV,B_^0^, C_FUV,B_^0^, and C_FUV,NUV_^0^, are derived according to the stellar parameters from the LAMOST spectroscopic survey and photometric results from the GALEX and APASS surveys. With the derived intrinsic colors, the ultraviolet color excesses are calculated for about 25,000 A- and F-type dwarf stars. Analysis of the color excess ratios yields the extinction law related to the GALEX UV bands: E_NUV,B_/E_B,V_=3.77, E_FUV,B_/E_B,V_=3.39, and E_FUV,NUV_/E_B,V_=-0.38. The results agree very well with previous works in the NUV band and in general with the extinction curve derived by Fitzpatrick (1999PASP..111...63F) for R_V_=3.35.
22767. Ultraviolet Imaging Telescope
ID:
ivo://archive.stsci.edu/uit
Title:
Ultraviolet Imaging Telescope
Short Name:
UIT
Date:
22 Jul 2020 21:32:30
Publisher:
Space Telescope Science Institute Archive
Description:
The Ultraviolet Imaging Telescope UIT was one of three ultraviolet telescopes on the ASTRO-1 mission flown on the space shuttle Columbia during 2-10 December 1990. The same three instruments were later flown on the space shuttle Endeavour from 3-17 March 1995, as part of the ASTRO-2 mission. Exposures were obtained on 70-mm photographic film in the 1200-3300 Å range using broadband filters and later digitized using a Perkin-Elmer microdensitometer. Image resolution was 3" over a 40' field of view. Overall, UIT-1 obtained 821 exposures of 66 targets, and UIT-2 obtained 758 images of 193 targets.
22768. Ultraviolet Imaging Telescope Master Catalog
ID:
ivo://nasa.heasarc/uitmaster
Title:
Ultraviolet Imaging Telescope Master Catalog
Short Name:
UITMASTER
Date:
28 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
The Ultraviolet Imaging Telescope (UIT) was one of three ultraviolet telescopes on the ASTRO-1 mission flown on the Space Shuttle Columbia during the period of 2 - 10 December 1990. The same three instruments were later flown on the Space Shuttle Endeavour during 3 - 17 March 1995, as part of the ASTRO-2 mission. Exposures were obtained on 70-mm photographic film in the 1200-3300 Angstrom range using broadband filters and later digitized using a Perkin-Elmer microdensitometer. The image resolution was 3 arcseconds over a 40 arcminute field of view and images of targets as faint as 21st (ultraviolet) magnitude were recorded. Overall, the UIT-1 mission obtained 821 exposures of 66 targets (361 near-UV and 460 far-UV), and UIT-2 obtained 758 images of 193 targets (all far-UV), for a total of 1579 exposures. This table contains only 1481 rows, 777 UIT-1 exposures (347 near-UV and 430 far-UV) and 704 UIT-2 exposures (all far-UV), implying that 98 exposures are &#39;missing&#39; from this table. This table was created by the HEASARC in April 2012 based on &lt;a href="https://cdsarc.cds.unistra.fr/ftp/cats/VI/104"&gt;CDS Catalog VI/104&lt;/a&gt; file uitlist.dat. This is a service provided by NASA HEASARC .
22769. Ultraviolet Imaging Telescope Near-UV Bright Objects Catalog
ID:
ivo://nasa.heasarc/uit
Title:
Ultraviolet Imaging Telescope Near-UV Bright Objects Catalog
Short Name:
UIT
Date:
28 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
The Ultraviolet Imaging Telescope (UIT) Near-UV Bright Objects Catalog is a photometric catalog of 2244 objects detected by the UIT in the near-ultraviolet (NUV; 1650A&lt;lambda&lt;2900A) during the Astro-1 Space Shuttle mission. Sources in the catalog are as faint as near-UV magnitude m_nuv of about 18.8, or near-UV flux f_nuv ~ 1.1x10&lt;sup&gt;-16ergs/s/cm&lt;/sup&gt;2/A, but the survey is not complete to this level. Optical catalogs were used to cross identify sources and derive near-UV to Johnson V colors. A majority of the objects (88%) do indeed have proposed optical identifications from catalogs, and most are stars. The authors&#39; purpose in creating the catalog was to form a database useful for identifying very blue objects and for performing Galactic UV stellar population studies. This database was created by the HEASARC in November 2000 based on a machine-readable version obtained from the CDS (Catalog J/ApJS/104/287). This is a service provided by NASA HEASARC .
22770. Ultraviolet Imaging Telescope (UIT)
ID:
ivo://mast.stsci/siap/uit
Title:
Ultraviolet Imaging Telescope (UIT)
Short Name:
UIT
Date:
23 Jul 2020 19:44:25
Publisher:
Space Telescope Science Institute Archive
Description:
The Ultraviolet Imaging Telescope UIT was one of three ultraviolet telescopes on the ASTRO-1 mission flown on the space shuttle Columbia during 2-10 December 1990. The same three instruments were later flown on the space shuttle Endeavour from 3-17 March 1995, as part of the ASTRO-2 mission. Exposures were obtained on 70-mm photographic film in the 1200-3300 Å range using broadband filters and later digitized using a Perkin-Elmer microdensitometer. Image resolution was 3" over a 40' field of view. Overall, UIT-1 obtained 821 exposures of 66 targets, and UIT-2 obtained 758 images of 193 targets.

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