J/MNRAS/315/839ivo://CDS.VizieR/J/MNRAS/315/839doi:10.26093/cds/vizier.73150839CDSMinns A.R.Riley J.M.2024-06-26T20:16:33Z2007-12-28T16:51:44ZCDS support team

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

cds-question@unistra.frgalaxiescatalogsradio-sourcesThe Cambridge Low-Frequency Synthesis Telescope has been used to produce a representative sample of low-frequency variable sources. 20 fields, each covering an area of approximately 9{deg}x9{deg}cosecDE, have been observed at 151MHz at between 2 and 10 epochs over the period from 1984 to 1996. At each epoch, maps were made with rms noise levels of typically 10^-15^mJy/beam. From a total of ~6000 sources detected on these maps, 207 are found for which the flux density variations between at least two epochs appear significant at greater than the 3{sigma} level. A numerical model is used to assess the true significance of the variability, given the analysis method adopted. This shows that for about half of the sources which appear to vary by >3{sigma} the variability is genuine. For the other half it is caused by random statistical fluctuations; most of the spurious variables vary by <=3.5{sigma} between a single pair of epochs. A catalogue of the variable sources is presented, which includes an estimate of the probability that a given source is a genuine variable. Fractional flux density variations of between 5 and 100% (typically 15-25%) have been detected on a range of time-scales from 1 to 12 years.2000MNRAS.315..839Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/315/839CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVIII/18 : 6C Survey of radio sources I. (Baldwin+ 1985)VIII/21 : 6C Survey of radio sources II. (Hales+ 1988)VIII/22 : 6C Survey of Radio Sources III. (Hales+ 1990)VIII/23 : 6C Survey of radio sources IV. (Hales+ 1991)VIII/24 : 6C Survey of Radio Sources V. (Hales+ 1993)VIII/25 : 6C Survey of radio sources VI. (Hales+ 1993)J/MNRAS/276/614 : Radio-optical 151MHz survey of the N. Ecl. Cap (Lacy+ 1995)J/MNRAS/298/637 : 7C: 151MHz survey of 3 regions (Pooley+, 1998)J/MNRAS/294/607 : 7C(G) 151MHz survey of the Galactic plane (Vessey+ 1998)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/315/839https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/315/839http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/315/839https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/315/839https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/315/839http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/315/839GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/315/839/table1 (List of variability fields)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/315/839/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/315/839/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/315/839/table1?GETtext/xml+votable180.050000true10.68432741.2738250.005555555555555556Cone search capability for table J/MNRAS/315/839/table7 (Catalogue of potential low-frequency variability (PLFV) sources)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/315/839/table7?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/315/839/table7?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/315/839/table7?GETtext/xml+votable180.050000true6.358966239.3265070.0055555555555555566/745 931 1009 1012 1397 1432 1447 1450 1453 1457 1466-1467 1501 1521 1674 1691 1697 1701 1708 1721 1831 2132 2307 2312 2314 2323 2330 2333 2353 2400 2404 2409 2419 2422 2425-2426 2496 2504 2610 2619 2622-2623 2660 2694 2709 3073 3112 3609 3614 3648-3649 3658 3663-3664 5209 5220 5222 5227 5229 5231 5234 5242 5246 5276 5278 5298 5303 5306 5311 5317 5325 5333-5334 5338 5341 5349 5352-5354 5362 5364 5370-5371 5386 5416 5423 5434 5505 5507 5513-5514 5535-5536 5538 5541 5546 5549 5553 5562 5719 5722 5725-5727 5734 5749 5753 5756 5758 5828 5837 5842 5848 5873 5879 5890 5893 5897 5906 5917-5918 5932 5935 5937-5938 6018 6035 6051-6052 6054 6056 6063 6066-6067 6070 6078-6079 6088 6090 6747 6760 6763 6775 6777-6778 6811 6820 6822 6824-6825 6829 6831 6834 6843-6844 6848 6853 6859-6860 6863 6865 6884 6946 6948 6958 7262 7426 7435 10419 10422 10426 10440 10445-10446 10484 10491 10634-10635 10667 10758 10768 10772-10773 10781 10800 10803 10806 10840 11551 11575 11606 11625-11626 11635 11714 14070 15351 15359 15590 15592 15602 15609 15891 15895 15900 159461.0005364593029448e-25 1.0005364593029448e-25https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/315/839?format=asciiRadiodefaultJ/MNRAS/315/839/table1List of variability fieldsFieldFieldmeta.id;meta.maincharprimaryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAB1950Right ascension (B1950)pos.eq.ra;meta.mainDEB1950Declination (B1950)pos.eq.dec;meta.main_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data)pos.eq.ranullableindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data)pos.eq.decnullableindexedJ/MNRAS/315/839/table7Catalogue of potential low-frequency variability (PLFV) sourcesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIAUIAU name (based on B1950 position)meta.id;meta.maincharFieldCLFST field (see table 1),obs.fieldcharn_Field[*] * indicates multiple fields (see Sect. 4)meta.notecharRAB1950Best available radio right ascension (B1950)pos.eq.ra;meta.mainDEB1950Best available radio declination (B1950)pos.eq.dec;meta.mainrpLFV position references (1)meta.ref;pos.framecharu_rp[?] Uncertainty flag on rpmeta.code.errorcharr_ID? LFV optical ID references in table9.datmeta.ref;pos.frameintnullableIDOptical identification code (2)src.classcharz? Redshift (if available)src.redshiftfloatnullableDS/S? Maximum observed percentage variability of 151MHz beam-fitted flux density between two epochs%phot.flux.density;em.radiofloatnullablesigmafSignificance of variabilitystat.fit.goodnessfloatNpairNumber of pairs of epochs between which 3.sigmaf variability has been detected;meta.numberintu_Npair[?*] ?: all cases of 3sigmaf variability have common epoch *: 3.sigmaf variability for at least two independent pairs of epochsmeta.code.errorcharl_PgenLimit flag on Pgenmeta.code.errorcharPgenProbability that variability is genuine (see Section 3)src.varfloatS151mMinimum value of observed range of 151MHz beam-fitted flux density (Jy/beam)Jyphot.flux.density;em.radio.100-200MHzfloatS151MMaximum value of observed range of 151MHz beam-fitted flux density (Jy/beam)Jyphot.flux.density;em.radio.100-200MHzfloatSILF? Low-frequency spectral index (4)spect.indexfloatnullablen_SILF[* ] *: between 151 and 365MHz unmarked: between 151 and 408MHzmeta.notecharSIHF? High-frequency spectral index (4)spect.indexfloatnullablen_SIHF[?* ] ?: between 1.4GHz and 15GHz *: between 1.4GHz and 4.85GHz unmarked: between 4.85GHz and 15GHzmeta.notecharSClassSpectral class (4) (3)meta.code.classchar_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data)pos.eq.ranullableindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data)pos.eq.decnullableindexedJ/MNRAS/315/839/table9LFV optical identification referencesBibcodeBibcodemeta.bib.bibcodecharAutAuthor's namemeta.bib.authorcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRefReference numbermeta.id;meta.mainintComCommentsmeta.notechar