Information on Service 'LoTSS-DR2 mosaics'

Further access options are discussed below

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.

For a list of all services and tables belonging to this service's resource, see Information on resource 'lotss_dr2/q'

Overview

You can access this service using:

siap.xml -- a standard SIAP interface as defined by the IVOA to access collections of celestial images; SIAP clients use https://vo.astron.nl/lotss_dr2/q/query_mosaics/siap.xml? to access the service
form -- allows access via an HTML form

This service is published as follows:

Within the set(s) local with the renderer form
Within the set(s) ivo_managed with the renderer siap.xml
Within the set(s) ivo_managed with the renderer tap

local means it is listed on our front page, ivo_managed means it has a record in the VO registry.

Other services provided on the underlying data include:

Spatial Coverage

Input Fields

The following fields are available to provide input to the service (with some renderers, some of these fields may be unavailable):

Name	Table Head	Description	Unit	UCD
FORMAT	Output format	Requested format of the image data	N/A	N/A
hFORMAT	Output format	Requested format of the image data	N/A	N/A
hINTERSECT	Intersection type	Relation of image and specified Region of Interest.	N/A	N/A
hPOS	Position	ICRS Position, RA,DEC, or Simbad object (e.g., 234.234,-32.45)	deg	pos.eq
hSIZE	Field size	Size in decimal degrees (e.g., 0.2 or 1,0.1)	deg	N/A
INTERSECT	Intersection type	Relation of image and specified Region of Interest.	N/A	N/A
MAXREC	Match limit	Maximum number of records returned. Pass 0 to retrieve service parameters.	N/A	N/A
POS	Position	ICRS Position, RA,DEC decimal degrees (e.g., 234.234,-32.46)	deg	pos.eq
RESPONSEFORMAT	Output Format	File format requested for output.	N/A	meta.code.mime
SIZE	Field size	Size in decimal degrees (e.g., 0.2 or 1,0.1)	deg	N/A
VERB	Verbosity	Exhaustiveness of column selection. VERB=1 only returns the most important columns, VERB=2 selects the columns deemed useful to the average user, VERB=3 returns a table with all available columns.	N/A	N/A

Default Output Fields

The following fields are contained in the output by default. More fields may be available for selection; these would be given below in the VOTable output fields.

Name	Table Head	Description	Unit	UCD
accref	Product key	Access key for the data	N/A	N/A
accsize	File size	Size of the data in bytes	byte	VOX:Image_FileSize
bandpassHi	Band upper	Upper limit of the bandpass (in BandPass_Unit units)	m	VOX:BandPass_HiLimit
bandpassId	Bandpass	Freeform name of the bandpass used	N/A	VOX:BandPass_ID
bandpassLo	Band lower	Lower limit of the bandpass (in BandPass_Unit units)	m	VOX:BandPass_LoLimit
bandpassRefval	Band Ref.	Characteristic quantity for the bandpass of the image	m	VOX:BandPass_RefValue
bandpassUnit	Bandpass unit	Unit of bandpass specifications (always m).	N/A	VOX:BandPass_Unit
centerAlpha	Ctr. RA	Approximate center of image, RA	deg	POS_EQ_RA_MAIN
centerDelta	Ctr. Dec	Approximate center of image, Dec	deg	POS_EQ_DEC_MAIN
coverage	Coverage	Field covered by the image	deg	N/A
data_PID	Persistent Identifier	EPIC PID of the data product (for citation).	N/A	meta.bib
dateObs	Obs. date	Epoch at midpoint of observation	d	VOX:Image_MJDateObs
imageTitle	Title	Synthetic name of the image	N/A	VOX:Image_Title
instId	Instrument	Identifier of the originating instrument	N/A	INST_ID
mime	Type	MIME type of the file served	N/A	meta.code.mime
mosaic_id	Mosaic ID	The name of the mosaic.	N/A	meta.id;meta.main
nAxes	#axes	Number of axes in data	N/A	VOX:Image_Naxes
pixelScale	Scales	The pixel scale on each image axis	deg/pix	VOX:Image_Scale
pixelSize	Axes Lengths	Number of pixels along each of the axes	pix	VOX:Image_Naxis
pixflags	P. Flags	Flags specifying the processing done (C-original; F-resampled; Z-fluxes valid; X-not resampled; V-for display only	N/A	VOX:Image_PixFlags
refFrame	Ref. Frame	Coordinate system reference frame	N/A	VOX:STC_CoordRefFrame
related_products	Related products	Link related products for the observation	N/A	meta.ref.url
wcs_cdmatrix	CD matrix	FITS WCS CDij matrix	deg/pix	VOX:WCS_CDMatrix
wcs_equinox	Equinox	Equinox of the given coordinates	yr	VOX:STC_CoordEquinox
wcs_projection	Proj.	FITS WCS projection type	N/A	VOX:WCS_CoordProjection
wcs_refPixel	Ref. pixel	WCS reference pixel	pix	VOX:WCS_CoordRefPixel
wcs_refValues	Ref. values	World coordinates at WCS reference pixel	deg	VOX:WCS_CoordRefValue

VOTable Output Fields

The following fields are available in VOTable output. The verbosity level is a number intended to represent the relative importance of the field on a scale of 1 to 30. The services take a VERB argument. A field is included in the output if their verbosity level is less or equal VERB*10.

Name	Table Head	Description	Unit	UCD	Verb. Level
centerAlpha	Ctr. RA	Approximate center of image, RA	deg	POS_EQ_RA_MAIN	0
centerDelta	Ctr. Dec	Approximate center of image, Dec	deg	POS_EQ_DEC_MAIN	0
imageTitle	Title	Synthetic name of the image	N/A	VOX:Image_Title	0
dateObs	Obs. date	Epoch at midpoint of observation	d	VOX:Image_MJDateObs	0
accref	Product key	Access key for the data	N/A	N/A	1
related_products	Related products	Link related products for the observation	N/A	meta.ref.url	1
data_PID	Persistent Identifier	EPIC PID of the data product (for citation).	N/A	meta.bib	1
bandpassId	Bandpass	Freeform name of the bandpass used	N/A	VOX:BandPass_ID	10
accsize	File size	Size of the data in bytes	byte	VOX:Image_FileSize	11
pixelScale	Scales	The pixel scale on each image axis	deg/pix	VOX:Image_Scale	12
instId	Instrument	Identifier of the originating instrument	N/A	INST_ID	15
pixelSize	Axes Lengths	Number of pixels along each of the axes	pix	VOX:Image_Naxis	15
mime	Type	MIME type of the file served	N/A	meta.code.mime	20
nAxes	#axes	Number of axes in data	N/A	VOX:Image_Naxes	20
refFrame	Ref. Frame	Coordinate system reference frame	N/A	VOX:STC_CoordRefFrame	20
wcs_equinox	Equinox	Equinox of the given coordinates	yr	VOX:STC_CoordEquinox	20
wcs_projection	Proj.	FITS WCS projection type	N/A	VOX:WCS_CoordProjection	20
wcs_refPixel	Ref. pixel	WCS reference pixel	pix	VOX:WCS_CoordRefPixel	20
wcs_refValues	Ref. values	World coordinates at WCS reference pixel	deg	VOX:WCS_CoordRefValue	20
wcs_cdmatrix	CD matrix	FITS WCS CDij matrix	deg/pix	VOX:WCS_CDMatrix	20
bandpassUnit	Bandpass unit	Unit of bandpass specifications (always m).	N/A	VOX:BandPass_Unit	20
bandpassRefval	Band Ref.	Characteristic quantity for the bandpass of the image	m	VOX:BandPass_RefValue	20
bandpassHi	Band upper	Upper limit of the bandpass (in BandPass_Unit units)	m	VOX:BandPass_HiLimit	20
bandpassLo	Band lower	Lower limit of the bandpass (in BandPass_Unit units)	m	VOX:BandPass_LoLimit	20
pixflags	P. Flags	Flags specifying the processing done (C-original; F-resampled; Z-fluxes valid; X-not resampled; V-for display only	N/A	VOX:Image_PixFlags	20
coverage	Coverage	Field covered by the image	deg	N/A	20
mosaic_id	Mosaic ID	The name of the mosaic.	N/A	meta.id;meta.main	20
owner	Owner	Owner of the data	N/A	N/A	25
embargo	Embargo ends	Date the data will become/became public	a	N/A	25

Copyright, License, Acknowledgements

LoTSS Data Release 2 is licensed under the Creative Commons Attribution Share-Alike 3.0 License

VOResource XML (that's something exclusively for VO nerds)

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