Continuum imagesivo://astron.nl/apertif_dr1/q/apertif_dr1_continuum_imagesASTRONApertif Team2024-10-21T12:54:16Michael Sipior

Oude Hoogeveensedijk 4, 7991PD Dwingeloo, the Netherlands

vo@astron.nlHI lineradio Apertif is a phased-array feed system for the Westerbork Synthesis Radio Telescope (WSRT), providing forty instantaneous beams over 300 MHz of bandwidth. This first data release includes observations in the first year of survey operations, from 1 July 2019 through 30 June 2020. The data release includes all raw observational data for a total of 221 observations of 160 independent target fields, covering approximately one thousand square degrees of sky. A subset of processed data products, meeting specified quality assessment criteria as outlined in Adams et al. (2022), are also released. Images and cubes are released on a per beam basis, and 3374 beams (of 7640 considered) are included in this data release. The processed data products are only available for the upper 150 MHz of the band over the range 1280–1430 MHz. The first 12.5 MHz of data are flagged due to persistent RFI resulting in a nominal bandwidth of 137.5 MHz and central frequency of 1361.25 MHz. The data products are not primary-beam corrected, however the primary-beam images are provided separately that may be used for mosaicking or for correction of individual images. This service queries the continuum images from the first data release of Apertif. Multi-frequency synthesis (mfs) Stokes I images are produced over the full frequency range (1292.5– 1430 MHz) and saved as fits files for each beam. The size of the continuum images is 3.4 deg × 3.4 deg (3073 × 3073 pixels, with 4''/pixel). The median noise in the continuum images is 41.4 uJy/beam and the median angular resolution is 11.6''/sin(declination). A companion VO table provides a continuum source catalog based on all continuum images contained in this data release and is described in Kutkin et al. (2022) (see https://vo.astron.nl/apertif_dr1/q/apertif_dr1_catalogue/form).2022A&A...667A..38Ahttps://vo.astron.nl/apertif_dr1/q/apertif_dr1_continuum_images/infoSurveyResearchserved-byThe VO @ ASTRON TAP serviceLicensed under CC-BYhttps://vo.astron.nl/apertif_dr1/q/apertif_dr1_continuum_images/scs.xml?GETapplication/x-votable+xmlRARight Ascension (ICRS decimal)degpos.eq.rarealDECDeclination (ICRS decimal)degpos.eq.decrealSRSearch radiusdegrealtargetName of the fieldmeta.idcharbeam_numberBeam numbermeta.id;instr.beamintegerobsidObservation idmeta.idcharRESPONSEFORMATFile format requested for output.meta.code.mimecharMAXRECMaximum number of records returned. Pass 0 to retrieve service parameters.integerVERBExhaustiveness 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.integer180100000true342.133.90.001https://vo.astron.nl/apertif_dr1/q/apertif_dr1_continuum_images/availabilityhttps://vo.astron.nl/apertif_dr1/q/apertif_dr1_continuum_images/capabilitieshttps://vo.astron.nl/apertif_dr1/q/apertif_dr1_continuum_images/tableMetadatahttps://vo.astron.nl/tapWSRTApertifRadioapertif_dr1apertif_dr1.continuum_imagesaccrefAccess key for the dataAccess.ReferencecharindexednullableownerOwner of the datacharnullableembargoDate the data will become/became publicacharnullablemimeMIME type of the file servedmeta.code.mimeAccess.FormatcharnullableaccsizeSize of the data in bytesbyteVOX:Image_FileSizeAccess.SizelongnullablecenteralphaApproximate center of image, RAdegpos.eq.ra;meta.maindoublenullablecenterdeltaApproximate center of image, Decdegpos.eq.dec;meta.maindoublenullableimagetitleSynthetic name of the imageVOX:Image_TitlecharnullableinstidIdentifier of the originating instrumentINST_IDcharnullabledateobsEpoch at midpoint of observationdVOX:Image_MJDateObsdoublenullablenaxesNumber of axes in dataVOX:Image_NaxesintnullablepixelsizeNumber of pixels along each of the axespixVOX:Image_NaxisintnullablepixelscaleThe pixel scale on each image axisdeg/pixVOX:Image_ScalefloatnullablerefframeCoordinate system reference frameVOX:STC_CoordRefFramecharnullablewcs_equinoxEquinox of the given coordinatesyrVOX:STC_CoordEquinoxfloatnullablewcs_projectionFITS WCS projection typeVOX:WCS_CoordProjectioncharnullablewcs_refpixelWCS reference pixelpixVOX:WCS_CoordRefPixelfloatnullablewcs_refvaluesWorld coordinates at WCS reference pixeldegVOX:WCS_CoordRefValuedoublenullablewcs_cdmatrixFITS WCS CDij matrixdeg/pixVOX:WCS_CDMatrixfloatnullablebandpassidFreeform name of the bandpass usedVOX:BandPass_IDcharnullablebandpassunitUnit of bandpass specifications (always m).VOX:BandPass_UnitcharnullablebandpassrefvalCharacteristic quantity for the bandpass of the imagemVOX:BandPass_RefValuefloatnullablebandpasshiUpper limit of the bandpass (in BandPass_Unit units)mVOX:BandPass_HiLimitfloatnullablebandpassloLower limit of the bandpass (in BandPass_Unit units)mVOX:BandPass_LoLimitfloatnullablepixflagsFlags specifying the processing done (C-original; F-resampled; Z-fluxes valid; X-not resampled; V-for display onlyVOX:Image_PixFlagscharnullablecoverageField covered by the imagedegdoubleindexednullabletargetName of the fieldmeta.idcharnullableobsidUnique idmeta.idcharnullablerelated_productsLink related products for the observationmeta.ref.urlcharnullablevalidWhether or not the dataset has passed validationmeta.code.qualchartask_idID of the taskmeta.idcharnullablebeam_numberNumber of the beammeta.id;instr.beamintfreqminMinimum frequencyMHzem.freqfloatfreqmaxMaximum frequencyMHzem.freqfloatn_channelsNumber of channelsem.binintpub_didDataset identifier assigned by the publishermeta.id;meta.maincharindexednullablesigma_inNoise in inner half degree of the imageuJy/beamstat.errorfloatsigma_outNoise at the edge of the residual image, more than a degree from the centreuJy/beamstat.errorfloatrsigma_in/sigma_outstat.error;arith.ratiofloatbminThe diameter of the FWHM minor axis of the synthesised beamarcsecphys.angsize;instr.beamfloatneg10The level at which the area covered by pixels with values below this level is 10 beams in units of sigma_outstat.valuefloatexneg2Area with values below -2 sigma_out in the inner 0.5 degree of the residual image in units of beam areaphys.angAreafloativoaDefinition and support code for the ObsCore data model and table.ivoa.obscoreThis data collection is queriable in The VO @ ASTRON's obscore table.