J/A+A/684/A132ivo://CDS.VizieR/J/A+A/684/A132doi:10.26093/cds/vizier.36840132CDSMandarakas N.Panopoulou G.V.Pelgrims V.Potter S.B.Pavlidou V.,Ramaprakash A.Tassis K.Blinov D.Kiehlmann S.Koutsiona E.,Maharana S.Romanopoulos S.Skalidis R.Vervelaki A.Clark S.E.,Kypriotakis J.A.Readhead A.C.S.2024-11-07T20:02:21Z2024-04-12T07:43:38ZCDS support team

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

cds-question@unistra.frinterstellar-mediumpolarimetryinfrared-astronomyThe calibration of optical polarimeters relies on the use of stars with negligible polarization (i.e., unpolarized standard stars) for determining the instrumental polarization zero point. For wide-field polarimeters, calibration is often done by imaging the same star over multiple positions in the field of view (FoV), which is a time-consuming process. A more effective technique is to target fields containing multiple standard stars. While this method has been used for fields with highly polarized stars, there are no such sky regions with well measured unpolarized standard stars. We aim to identify sky regions with tens of stars exhibiting negligible polarization that are suitable for a zero-point calibration of wide-field polarimeters. We selected stars in regions with extremely low reddening, located at high Galactic latitudes. We targeted four ~40'x40' fields in the northern and eight in the southern equatorial hemispheres. Observations were carried out at the Skinakas Observatory and the South African Astronomical Observatory. Results. We found two fields in the north and seven in the south characterized by a mean polarization lower than p<0.1%. At least 9 out of the 12 fields can be used for a zero-point calibration of wide-field polarimeters.2024A&A...684A.132Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/684/A132CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/684/A132https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/684/A132http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/684/A132https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/684/A132https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/684/A132http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/684/A132GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/684/A132/catalog (Catalog of polarimetric measurements)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/684/A132/catalog?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/684/A132/catalog?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/684/A132/catalog?GETtext/xml+votable180.050000true246.480843.93560.0055555555555555565/11569 11571 6/6065 6067-6068 6070 6115 9821 9992 11491 11494 33948-33950 34334-34335 34356-34357 35932 35934-35935 46191 46297 46299-46300https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/684/A132?format=asciiInfrareddefaultJ/A+A/684/A132/catalogCatalog of polarimetric measurementsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaDR3GAIA DR3 source_idmeta.id;meta.mainRA_ICRSRight Ascension (ICRS) at Ep=2026.0degpos.eq.ra;meta.mainDE_ICRSDeclination (ICRS) at Ep=2026.0degpos.eq.dec;meta.mainqq=Q/I Stokes parameterphys.polarization.stokesdoublee_qUncertainty of qstat.errordoubleuu=U/I Stokes parameterphys.polarization.stokesdoublee_uUncertainty of ustat.errordoublepPolarization degreephys.polarizationdoubledebpDebiased estimator of pphys.polarizationdoublee_pUncertainty of pstat.errordoubleEVPAPolarization position angle North-to-Eastdegpos.posAng;phys.polarizationfloate_EVPA[] Uncertainty of EVPAdegstat.errorfloatFieldzero-polarization candidate fieldmeta.id;obs.fieldchar