J/AJ/167/273ivo://CDS.VizieR/J/AJ/167/273doi:10.26093/cds/vizier.51670273CDSTaylor A.R.Legodi L.S.2024-11-06T20:20:20Z2024-07-01T08:03:17ZCDS support team

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

cds-question@unistra.frradio-continuum-emissioninterferometryactive-galactic-nucleiWe report on full-Stokes L-band observations of 98 MeerKAT calibration sources. Linear polarization is detected in 71 objects above a fractional level of 0.2%. We identify ten sources with strong fractional linear polarization and low Faraday rotation measure that could be suitable for wide-band absolute polarization calibration. We detect significant circular polarization from 24% of the sample down to a detection level of 0.07%. Circularly polarized emission is seen only for flat spectrum sources {alpha}>-0.5. We compare our polarized intensities and Faraday synthesis results to data from the NVSS at 1400MHz and the ATCA SPASS survey at 2300MHz. NVSS data exist for 54 of our sources and SPASS data for 20 sources. The percent polarization and rotation measures from both surveys agree well with our results. The residual instrumental linear polarization for these observations is measured at 0.16%, and the residual instrumental circular polarization is measured at 0.05%. These levels may reflect either instabilities in the relative bandpass between the two polarization channels with either time or antenna orientation, or atmospheric/ionospheric variations with pointing direction. Tracking of the hourly gain solutions on J0408-6545 after transfer of the primary gain solutions suggests a deterioration of the gain stability by a factor of several starting about 2hr after sunrise. This suggests that observing during the nighttime could dramatically improve the precision of polarization calibration.2024AJ....167..273Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/167/273CatalogResearchIsServedByTAP VizieR generic servicerelated-toVII/2 : Master list of radio sources, updated 1978 (Dixon, 1970)VIII/38 : The Parkes-MIT-NRAO 4.85GHz (PMN) Surveys (Griffith+ 1993-1996)VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)VIII/74 : SPECFIND Catalog of radio continuum spectra (Vollmer+ 2005)VIII/85 : SPECFIND V2.0 Catalog of radio continuum spectra (Vollmer+ 2009)J/ApJ/702/1230 : Rotation measure image of the sky (Taylor+, 2009)J/ApJS/212/15 : Polarized NVSS sources SEDs (Farnes+, 2014)J/ApJ/829/5 : SPASS & NVSS bright extragalactic radio sources (Lamee+, 2016)J/other/PASA/34.13 : S-PASS catalog at 2.3GHz (Meyers+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/167/273https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/167/273http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/167/273https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/167/273https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/167/273http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/167/273GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapRadiodefaultJ/AJ/167/273/table3Polarization properties of MeerKAT calibrator sourcesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintS1.4GHz[0.52/16.2] Flux density at 1400MHz from a power-law fit to the Stokes I spectrum (1)Jyphot.flux.density;em.radio.750-1500MHzfloate_S1.4GHz[0.001/0.02] Uncertainty in S1.4GHz (1)Jystat.errorfloatalpha[-1.31/1.48] In-band spectral index, Equation 11 (1)spect.indexfloate_alpha[0.001/0.02] Uncertainty in alpha (1)stat.error;spect.indexfloatC[-0.83/0.68] Curvature term from spectral fit to the Stokes I spectrumstat.fit.paramfloate_C[0.003/0.04] Uncertainty in Cstat.errorfloatp1400[0.01/9.9] Percent polarized intensity at 1400MHz (2)%stat.fit.paramfloate_p1400[0.0/0.013] Uncertainty in p1400 (2)%stat.errorfloatPA1400[-86.5/84.8] Position angle at 1400 MHz (2)degpos.posAngfloate_PA1400[0.1/21.7] Uncertainty in PA1400 (2)degstat.errorfloatbeta[-7.37/3.25] Spectral index of polarized intensity (3)spect.indexfloate_beta[0.01/0.34] Uncertainty in beta (3)stat.errorfloatRM[-127/107] Faraday depth of dominant rotation measure synthesis componentrad.m**-2phys.veloc.rotatfloate_RM[0.1/2] Uncertainty in RMrad.m**-2stat.errorfloatpmax[0.02/9.39] Amplitude (percent polarization) of dominant rotation measure synthesis component%src.var.amplitudefloate_vmed[0.001/0.003] Uncertainty in vmed (4)%stat.errorfloatvmed[-0.23/0.36] Median value fractional Stokes V over the band (4)%phys.polarization.stokes;stat.medianfloatv1400[-0.22/0.31] Circular polarization at 1400MHz from spectral fit to v spectrum%phys.polarization.circularfloate_v1400[0.001/0.02] Uncertainty in v1400%stat.errorfloatNameJ2000-based source namemeta.id;meta.mainchar