J/AJ/159/61ivo://CDS.VizieR/J/AJ/159/61doi:10.26093/cds/vizier.51590061CDSLee C.-H.Matheson T.Soraisam M.Narayan G.Saha A.Stubens C.,Wolf N.2022-03-07T07:17:25Z2020-03-27T08:37:48ZCDS support team

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

cds-question@unistra.frinfrared-photometryvisible-astronomybroad-band-photometryspectroscopyvariable-starsR Coronae Borealis stars (RCBs) constitute a rare class of stars that are hydrogen depleted and carbon enriched, possibly from white dwarf mergers. RCBs are identified by their stochastic dimming with photometric variations of as much as eight magnitudes. Hence, the discoveries of RCBs were heavily biased to the limited regions monitored by long-term microlensing experiments. However, recent studies of galactic RCBs have shown that they exhibit distinct mid-infrared colors originating from their cool circumstellar shells. The all-sky Wide-field Infrared Survey Explorer (WISE) survey thus facilitates the identification of RCB candidates. Therefore, combining the WISE colors with large-area time-domain surveys will enable us to discover more RCBs. Here we present the results of a first attempt to identify RCBs in the public Zwicky Transient Facility (ZTF) alert stream, using the alert broker ANTARES. We identify a candidate RCB using the infrared color selection by Tisserand+, 2013A&A...551A..77T and large light curve variations in the optical from ZTF. We then conduct subsequent observations using the FLOYDS spectrograph at the Las Cumbres Observatory and confirm ZTF18abhjrcf as a bona fide RCB. This demonstrates the potential to discover uncharted RCBs as ZTF and other time-domain surveys continue to operate.2020AJ....159...61Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/159/61CatalogResearchIsServedByTAP VizieR generic servicerelated-toII/264 : ASAS Variable Stars in Southern hemisphere (Pojmanski+, 2002-2005)VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)J/A+A/353/287 : The R CrB stars (Asplund+, 2000)J/AJ/134/1877 : Spectropolarimetry of R CrB in 1998-2003 (Kawabata+, 2007)J/AcA/59/335 : VI light curves of LMC R CBr stars (Soszynski+, 2009)J/PASP/123/1149 : NSV 11154 BVRI light curves (Kijbunchoo+, 2011)J/A+A/539/A51 : Catalogue enriched with R CrB stars (Tisserand, 2012)J/ApJ/747/102 : ^12^C/^13^C ratio for 18 galactic R CrB stars (Hema+, 2012)J/A+A/555/A24 : Aperture-synthesis imaging of Antares (Ohnaka+, 2013)J/A+A/559/A9 : Neutrinos from GRBs with ANTARES (Adrian-Martinez+ 2013)J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)J/other/NewA/51.1 : AS CrB BVRI light curves (Liu+, 2017)J/AJ/156/148 : Multiwavelength photometry of RCB stars (Montiel+, 2018)J/MNRAS/482/4174 : Heliocentric radial velocities of R CrB (Feast+, 2019)J/A+A/635/A14 : New R Coronae Borealis stars (Tisserand+, 2020)http://antares.noao.edu/ : ANTARES home pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/159/61https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/159/61http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/159/61https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/159/61https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/159/61http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/159/61GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/AJ/159/61/fig1g and r light curves of ZTF18abhjrcf from the Zwicky Transient Facility (ZTF) alertsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJD[58336/58749] Modified Julian Date (JD-2400000.5)dtime.epochdoublemag[14/22] Observed magnitude in Filtmagphot.magfloate_mag[0.03/1.7] Uncertainty in magmagstat.error;phot.magfloatFilt[gr] Filter used; g-band (24 occurrences) or r-band (23 occurrences)instr.setup;instr.filtercharJ/AJ/159/61/fig3Faulkes Telescope North/FLOYDS spectrum of ZTF18abhjrcfrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambda[3300/10183] Wavelength in Angstrom0.1nmem.wldoubleFlux[-0.03/1.1] Flux, normalizedphot.flux;arith.ratiodouble