In this data release from the ongoing LOw-Frequency ARray (LOFAR)
Two-metre Sky Survey (LoTSS) we present 120-168 MHz images covering
27% of the northern sky. Our coverage is split into two regions
centred at approximately 12h45m +44°30′ and 1h00m +28°00′ and spanning
4178 and 1457 square degrees respectively. The images were derived
from 3,451 hrs (7.6 PB) of LOFAR High Band Antenna data which were
corrected for the direction-independent instrumental properties as
well as direction-dependent ionospheric distortions during extensive,
but fully automated, data processing. A catalogue of 4,395,448 radio
sources is derived from our total intensity (Stokes I) maps, where the
majority of these have never been detected at radio wavelengths
before. At 6′′ resolution, our full bandwidth Stokes I continuum maps
with a central frequency of 144 MHz have: a median rms sensitivity of
83 μ Jy/beam; a flux density scale accuracy of approximately 10%; an
astrometric accuracy of 0.2′′; and we estimate the point-source
completeness to be 90% at a peak brightness of 0.8 mJy/beam. By
creating three 16 MHz bandwidth images across the band we are able to
measure the in-band spectral index of many sources, albeit the error
on the derived spectral index is > ±0.2 which is a consequence of our
flux-density scale accuracy and small fractional bandwidth. Our
circular polarisation (Stokes V) 20′′ resolution 120-168 MHz continuum
images have a median rms sensitivity of 95 μ Jy/beam, and we estimate
a Stokes I to Stokes V leakage of 0.056%. Our linear polarisation
(Stokes Q and Stokes U) image cubes consist of 480 97.6 kHz wide
planes and have a median rms sensitivity per plane of 10.8mJy/beam at
4′ and 2.2mJy/beam at 20′′; we estimate the Stokes I to Stokes Q/U
leakage to be approximately 0.2%. Here we characterise and publicly
release our Stokes I, Q, U and V images in addition to the calibrated
uv-data to facilitate the thorough scientific exploitation of this
unique dataset. This service queries the Stokes I continuum mosaic
images.
In this data release from the ongoing LOw-Frequency ARray (LOFAR)
Two-metre Sky Survey (LoTSS) we present 120-168 MHz images covering
27% of the northern sky. Our coverage is split into two regions
centred at approximately 12h45m +44°30′ and 1h00m +28°00′ and spanning
4178 and 1457 square degrees respectively. The images were derived
from 3,451 hrs (7.6 PB) of LOFAR High Band Antenna data which were
corrected for the direction-independent instrumental properties as
well as direction-dependent ionospheric distortions during extensive,
but fully automated, data processing. A catalogue of 4,395,448 radio
sources is derived from our total intensity (Stokes I) maps, where the
majority of these have never been detected at radio wavelengths
before. At 6′′ resolution, our full bandwidth Stokes I continuum maps
with a central frequency of 144 MHz have: a median rms sensitivity of
83 μ Jy/beam; a flux density scale accuracy of approximately 10%; an
astrometric accuracy of 0.2′′; and we estimate the point-source
completeness to be 90% at a peak brightness of 0.8 mJy/beam. By
creating three 16 MHz bandwidth images across the band we are able to
measure the in-band spectral index of many sources, albeit the error
on the derived spectral index is > ±0.2 which is a consequence of our
flux-density scale accuracy and small fractional bandwidth. Our
circular polarisation (Stokes V) 20′′ resolution 120-168 MHz continuum
images have a median rms sensitivity of 95 μ Jy/beam, and we estimate
a Stokes I to Stokes V leakage of 0.056%. Our linear polarisation
(Stokes Q and Stokes U) image cubes consist of 480 97.6 kHz wide
planes and have a median rms sensitivity per plane of 10.8mJy/beam at
4′ and 2.2mJy/beam at 20′′; we estimate the Stokes I to Stokes Q/U
leakage to be approximately 0.2%. Here we characterise and publicly
release our Stokes I, Q, U and V images in addition to the calibrated
uv-data to facilitate the thorough scientific exploitation of this
unique dataset. This service queries the Stokes I continuum mosaic
source catalogue.
WFAU, Institute for Astronomy, University of Edinburgh
Description:
The Millennium Galaxy Catalogue (MGC) is a 37.5 deg2, medium-deep, B-band imaging survey obtained with the Wide Field Camera on the INT. The survey region is a long, 35 arcmin wide strip along the equator, covering from 10h 00m to 14h 45m and is fully contained within the regions of both the Two Degree Field Galaxy Redshift Survey (2dFGRS) and the Sloan Digital Sky Survey (SDSS).
These spectra are optical follow-up observations of the
X-ray sources detected in the 942 ks exposure of the
Chandra Deep Field-South (CDFS) using FORS.
WFAU, Institute for Astronomy, University of Edinburgh
Description:
This service hosts the public releases of the ATLAS Survey housed at the Wide Field Astronomy Unit at the Univeristy of Edinburgh, as well as a number of other external datasets for which WFAU has neighbour tables, that can be cross matched with ATLAS. The initial aim of ATLAS is to survey 4500 deg2 of the Southern Sky at high galactic latitudes to comparable depths to the SDSS in the North. The VST ATLAS will be the first step towards a panoramic digital survey of the Southern Sky in the optical bands. The ATLAS will complement the proposed VISTA Hemisphere Survey in the South.
SDSS DR9 - Sloan Digital Sky Survey Data Release 9
Date:
04 Dec 2019 13:36:43
Publisher:
WFAU, Institute for Astronomy, University of Edinburgh
Description:
This is an AstroGrid Dataset Access installation of the Sloan Digital Sky Survey (SDSS) DR9 hosted by the Wide Field Astronomy Unit (WFAU), University of Edinburgh. WFAU would like to thank John Hopkins University and the University of Chicago for permission to host the data.
SDSS DR8 - Sloan Digital Sky Survey Data Release 8
Short Name:
SDSS DR8
Date:
04 Dec 2019 13:36:31
Publisher:
WFAU, Institute for Astronomy, University of Edinburgh
Description:
This is an AstroGrid Dataset Access installation of the Sloan Digital Sky Survey (SDSS) DR8 hosted by the Wide Field Astronomy Unit (WFAU), University of Edinburgh. WFAU would like to thank John Hopkins University and the University of Chicago for permission to host the data.
SDSS DR7 - Sloan Digital Sky Survey Data Release 7
Short Name:
SDSS DR7
Date:
04 Dec 2019 13:36:17
Publisher:
WFAU, Institute for Astronomy, University of Edinburgh
Description:
This is an AstroGrid Dataset Access installation of the Sloan Digital Sky Survey (SDSS) DR7 hosted by the Wide Field Astronomy Unit (WFAU), University of Edinburgh. WFAU would like to thank John Hopkins University and the University of Chicago for permission to host the data.