J/MNRAS/235/1313ivo://CDS.VizieR/J/MNRAS/235/1313doi:10.26093/cds/vizier.72351313CDSSlee O.B.Siegman B.C.2013-03-04T07:05:14Z1997-12-09T21:32:45ZCDS support team

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

cds-question@unistra.frradio-sourcesWe report a detailed statistical study of the intensity variations in 412 extragalactic radio sources randomly selected from the ~2000 sources which have been observed with the Culgoora circular array at 80 and 160 MHz during the interval 1970-84. Our results are: (i) About 47 per cent of the sample displays significant variability on time scales of months or years. (ii) A similar degree of variability is shown by QSOs, radio galaxies and sources in blank optical fields. (iii) Sources with flatter radio spectra are more variable. (iv) There is a weak increase in variability for the lower-galactic-latitude sources. (v) There is a correlation between month-to-month variability and year-to year variability in the same sources. (vi) The degree of variability at 80MHz is related to that at 160MHz. (vii) Most of the sources in both the variable and non-variable categories have a component with angular diameter <1arcsec. Our results are partly consistent with an origin in refractive scintillation by large-scale electron density turbulence in the intervening medium. There are, however, serious difficulties in explaining, from the existing theory of slow galactic scintillation, the short time-scale of the scintillation. Our results are probably more in accord with the focusing and occulting effects of compact interstellar ionized structures recently identified at microwave frequencies.1988MNRAS.235.1313Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/235/1313CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVIII/35 : Radio Sources observed with Culgoora Circular Arrayhttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/235/1313https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/235/1313http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/235/1313https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/235/1313https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/235/1313http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/235/1313GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/235/1313/table (Variability Measurements from the Culgoora Circular Array)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/235/1313/table?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/235/1313/table?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/235/1313/table?GETtext/xml+votable180.050000true1.59691-0.0741560.0055555555555555566/3 18 45 64 103 145 149 162 165 244 245 263 289 392 513 532 556 686 928 946 975 986 1129 2062 2063 2066 2111 2136 2164 2225 2245 2324 4120 4161 4179 4267 4280 4285 4303 4324 4341 4352 4366 4376 4448 4463 4511 4539 4569 4620 4649 4706 4754 4770 4790 4805 4835 4924 5005 5027 5284 5352 5413 6193 6195 6213 6273 6335 6536 8220 8223 8264 8268 8288 8322 8440 8514 8523 8526 8528 8552 8612 8626 8644 8675 8784 8786 8809 8812 8826 8963 8989 9009 9104 9252 9273 9375 9398 9508 10266 10271 10288 10312 10355 10374 10387 10432 10529 10761 12322 12335 12359 12459 12487 12525 12538 12551 12560 12571 12593 12673 12684 12744 12796 13007 13120 13158 13455 14347 14376 16434 16496 16509 16511 16614 16697 16713 16722 16764 16787 16806 16993 17019 17095 17141 17150 17224 17237 17319 17341 17441 17445 17485 17488 17576 17604 17620 17675 17684 17719 17754 17906 17914 17945 17979 18016 18017 18022 18063 18065 18066 18089 18151 18208 18227 18231 18272 18307 18320 18365 18387 18411 18437 18531 18567 18622 18661 18680 18713 18752 18778 18784 18812 18862 18887 18895 18928 19040 19060 19101 19157 19166 19190 19263 19285 19315 19325 19326 19330 19398 19413 19425 19426 19451 19485 19543 19645 19664 19745 19782 19797 19842 19857 19900 19905 19912 19935 19968 20030 20083 20099 20282 20529 20674 20689 20706 20715 20758 20802 20813 20823 20875 21090 21109 21126 21133 21143 21156 21232 21297 21373 21445 21588 21653 21713 21753 21774 21789 21811 21905 21935 21942 21955 21982 22238 22364 22375 22452 22475 22501 22524 22577 22658 22659 22754 22767 22844 22917 22947 22957 22976 22987 23025 23045 23075 23077 23128 23185 23269 23281 23291 23323 23393 23469 23476 23529 23547 23608 23644 23647 23688 23716 23765 23850 23979 24003 24014 24023 24116 24247 24300 24349 24388 24615 24710 24722 24753 24759 24867 24902 24923 24936 24943 24995 25016 25055 25126 25144 25233 25302 25344 25405 25444 25465 25472 25479 25530 25557 25590 25626 25666 25720 25743 25762 25810 25865 25870 25885 25900 25905 25914 25953 25980 25981 26031 26067 26100 26125 26131 26149 26167 26195 26292 26374 26455 26511 26525 26582 26678 26679 26713 26730 26736 26758 26830 26916 26932 26966 27025 27026 27030 27060 27074 27097 27206 27238 27241 27366 27392 27408 27442 27484 27486 27493 27514 27521 27532 27613 27632 27672 27765 27777 27872 27955 27984 27998 28059 28063 28149 28167 28171 28198 28237 28249 28279 28285 28336 28351 28355 28356 28391 28415 28460 28467 28479 28481 28542 28564 28574 28603 28610 28742 28994 29186 29211 29259 29320 29452 29570 29618 29711 29715 29799 29812 29889 29918 29991 30010 30137 30140 30252 30374 30491 30656 30737 30840 30844 30867 30885 31080 31193 31268 31332 31333 31346 31352 31406 31421 31509 31528 31664 31717 31766 31829 31832 31851 31877 31940 32017 32059 32314 32331 32360 32394 32455 32542 32570 32594 34123 34140 34210 34250 34264 34273 34443 34498 34535 34575 34648 34650 34666 34669 35383 35398 35413 35427 35434 35467 35666 35685 35788 35952 36003 36082 36178 36209 36219 36313 36431 36527 36595 36652 36661 36791 38139 38347 38364 38376 38483 38705 38820 39235 39308 39366 39368 39614 39617 39658 39685 39785 39795 39840 39907 39982 40023 40096 40141 40216 40255 40265 40297 40527 40529 40533 40547 40615 40692 40777 40946 42564 42648 42735 42901 42930 42955 43366 43417 43449 43461 43463 43491 43503 43519 43566 43626 43627 43670 43672 43686 43793 43828 43830 43881 43948 43981 43988 44028 44068 44144 44201 44215 44362 44426 44442 44475 44523 44549 44604 44662 44718 44809 44832 44859 44938 44969 45006 45011 45012 45031 46399 46437 46442 46444 46483 46512 46562 46573 46654 46662 46708 46715 46769 46848 46860 47007 47022 47325 47352 47512 47533 47678 47775 47801 47810 47849 47881 47895 47898 47910 48053 48076 48159 48161 48169 48256 48283 48449 48488 48493 48496 48501 48523 48529 48572 48594 48614 48625 48649 48770 48849 490155.300855537763051e-26 1.0601711075526101e-25https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/235/1313?format=asciiRadiodefaultJ/MNRAS/235/1313/tableVariability Measurements from the Culgoora Circular ArrayrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource namemeta.id;meta.maincharRAB1950Right ascension (B1950)pos.eq.ra;meta.mainDEB1950Declination (B1950)pos.eq.dec;meta.mainOptIDOptical Identificationmeta.id.crosscharz? Redshift of optical identificationsrc.redshiftfloatnullablealpha? Radio spectral indexspect.index;em.radiofloatnullableGLONGalactic longitudedegpos.galactic.lonGLATGalactic latitudedegpos.galactic.latfloatF80MHz? Average flux density at 80 MHzJyphot.flux.density;em.radio.20-100MHzfloatnullableo_F80MHz? Number of observations at F80MHzmeta.numberintnullableM1a? 1-monthly 80 MHz modulation index (1)meta.code;spect.index;em.radio.20-100MHzfloatnullableM12a? 12-month 80 MHz modulation index (1)meta.code;spect.index;em.radio.20-100MHzfloatnullableF160MHz? Average flux density at 160 MHzJyphot.flux.density;em.radio.100-200MHzfloatnullableo_F160MHz? Number of observations at F160MHzmeta.numberintnullableM1b? 1-month 160 MHz modulation index (1)meta.code;spect.index;em.radio.100-200MHzfloatnullableM12b? 12-month 160 MHz modulation index (1)meta.code;spect.index;em.radio.100-200MHzfloatnullable_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.decnullableindexed