J/A+A/673/A113ivo://CDS.VizieR/J/A+A/673/A113doi:10.26093/cds/vizier.36730113CDSWagenveld J.D.Kloeckner H.-R.Gupta N.Deka P.P.Jagannathan P.,Sekhar S.Balashev S.A.Boettcher E.Combes F.Emig K.L.Hilton M.,Jozsa G.I.G.Kamphuis P.Klutse D.Y.Knowles K.Krogager J.-K.,Mohapatra A.Momjian E.Moodley K.Muller S.Petitjean P.Salas P.,Sikhosana S.Srianand R.2026-01-20T12:11:36Z2023-05-17T08:41:53ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frsurveysradio-galaxiesgalaxy-classification-systemsThe number counts of homogeneous samples of radio sources are a tried and true method of probing the large-scale structure of the Universe, as most radio sources outside the Galactic plane are at cosmological distances. As such, they are expected to trace the cosmic radio dipole, an anisotropy analogous to the dipole seen in the cosmic microwave background (CMB). Results have shown that although the cosmic radio dipole matches the direction of the CMB dipole, it has a significantly larger amplitude. This unexplained result challenges our assumption of the Universe being isotropic, which can have large repercussions for the current cosmological paradigm. Though significant measurements have been made, sensitivity to the radio dipole is generally hampered by systematic effects that can cause large biases in the measurement. Here we assess these systematics with data from the MeerKAT Absorption Line Survey (MALS), a blind search for absorption lines with pointings centred on bright radio sources. With the sensitivity and field of view of MeerKAT, thousands of sources are observed in each pointing, allowing for the possibility of measuring the cosmic radio dipole given enough pointings. We present the analysis of ten MALS pointings, focusing on systematic effects that could lead to an inhomogeneous catalogue. We describe the calibration and creation of full band continuum images and catalogues, producing a combined catalogue containing 16307 sources and covering 37.5 square degrees of sky down to a sensitivity of 10uJy/beam. We measure the completeness, purity, and flux recovery statistics for these catalogues using simulated data. We investigate different source populations in the catalogues by looking at flux densities and spectral indices and how they might influence source counts. Using the noise characteristics of the pointings, we find global measures that can be used to correct for the incompleteness of the catalogue, producing corrected number counts down to 100-200uJy. We show that we can homogenise the catalogues and properly account for systematic effects. We determine that we can measure the dipole to 3{sigma} significance with 100 MALS pointings.2023A&A...673A.113Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/673/A113CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/673/A113https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/673/A113http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/673/A113https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/673/A113https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/673/A113http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/673/A113GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/673/A113/mals-ten (MALS 10 pointings catalogue)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/673/A113/mals-ten?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/673/A113/mals-ten?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/673/A113/mals-ten?GETtext/xml+votable180.050000true0.00035806-15.915538060.0055555555555555565/38 4291 4601 4925 6561 6745 9191 11892 6/33-36 38-39 41 44-45 141 143 165 176-177 17158-17159 17170 17176 17178 18382-18383 18416 18418 19708-19709 19872 19874 19880 24902-24903 24908-24909 24911 24914-24915 24920-24922 26158-26159 26170 26256 26258 26958-26959 26989 26992 26994 36788-36789 36808 36810 36832 47557 47559 47565 47576-475778.415108227908925e-25 8.415108227908925e-25https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/673/A113?format=asciiOpticalRadiodefaultJ/A+A/673/A113/mals-tenMALS 10 pointings cataloguerecnoRecord number assigned by the VizieR team. 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Intensity weighted mean right ascension of island from cutout (RA_mean)degpos.eq.ranullableDEImdeg? Intensity weighted mean declination of island from cutout (DEC_mean)degpos.eq.decnullableCutFtot? Total flux density at 1.27GHz of island from cutout (Cutout_Total_flux)mJyphot.flux.density;em.radio.750-1500MHzdoublenullableCutSpIndex? Intensity weighted mean spectral index from cutout (Cutout_Spectral_index)spect.indexdoublenullableCutFlagCutout flag(s) (Cutout_flag) (2)meta.codecharCutClass[GIPA] Classification from visual inspection of cutout (Cutout_class) (3)meta.code.classcharSCode[SMC] PyBDSF source flag (S_Code) (1)meta.codechare_FpeakError on peak flux density (E_Peak_flux)mJy/beamstat.errordoubleSpIndexCorrCorrection factor for residual primary beam effects spectral index (Spectral_index_correction)instr.paramdoublee_SpIndex? 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