J/ApJ/916/81ivo://CDS.VizieR/J/ApJ/916/81doi:10.26093/cds/vizier.19160081CDSCantu S.A.Pace A.B.Marshall J.Strigari L.E.Crnojevic D.Simon J.D.,Drlica-Wagner A.Bechtol K.Martinez-Vazquez C.E.Santiago B.Amara A.,Stringer K.M.Diehl H.T.Aguena M.Allam S.Avila S.Brooks D.,Carnero Rosell A.Carrasco Kind M.Carretero J.Costanzi M.,Da Costa L.N.De Vicente J.Desai S.Doel P.Eifler T.F.Everett S.,Frieman J.Garcia-Bellido J.Gaztanaga E.Gruen D.Gruendl R.A.,Gschwend J.Gutierrez G.Hinton S.R.Hollowood D.L.Honscheid K.,James D.J.Kuehn K.Maia M.A.G.Menanteau F.Miquel R.Palmese A.,Paz-Chinchon F.Plazas A.A.Sanchez E.Scarpine V.Schubnell M.,Serrano S.Sevilla-Noarbe I.Smith M.Soares-Santos M.Suchyta E.,Swanson M.E.C.Tarle G.Walker A.R.Wilkinson R.D.,The DES Collaboration.2023-10-03T12:58:23Z2022-12-15T14:10:17ZCDS support team

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

cds-question@unistra.frgalaxiesphotometryvisible-astronomysurveysWe present deep g- and r-band Magellan/Megacam photometry of two dwarf galaxy candidates discovered in the Dark Energy Survey (DES), Grus I and Indus II (DES J2038-4609). For the case of Grus I, we resolved the main sequence turn-off (MSTO) and ~2 mags below it. The MSTO can be seen at g_0_~24 with a photometric uncertainty of 0.03mag. We show Grus I to be consistent with an old, metal-poor (~13.3Gyr, [Fe/H]~-1.9) dwarf galaxy. We derive updated distance and structural parameters for Grus I using this deep, uniform, wide-field data set. We find an azimuthally-averaged halflight radius more than two times larger (~151^+21^_-31_pc; ~4.16'_-0.74_^+0.54^) and an absolute V-band magnitude ~-4.1 that is ~1 magnitude brighter than previous studies. We obtain updated distance, ellipticity, and centroid parameters that are in agreement with other studies within uncertainties. Although our photometry of Indus II is ~2-3 magnitudes deeper than the DES Y1 public release, we find no coherent stellar population at its reported location. The original detection was located in an incomplete region of sky in the DES Y2Q1 data set and was flagged due to potential blue horizontal branch member stars. The best-fit isochrone parameters are physically inconsistent with both dwarf galaxies and globular clusters. We conclude that Indus II is likely a false positive, flagged due to a chance alignment of stars along the line of sight.2021ApJ...916...81Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/916/81CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)II/371 : The Dark Energy Survey (DES): Data Release 2 (Abbott+, 2021)J/MNRAS/380/281 : Faint galactic satellites sp. survey (Martin+, 2007)J/ApJ/756/79 : Opt. photometry in 3 Local Group dwarf galaxies (Sand+, 2012)J/ApJ/819/53 : Magellan/M2FS sp. of Tucana 2 and Grus 1 (Walker+, 2016)J/ApJ/866/22 : Spectroscopic analysis of Tuc III stream (Li+, 2018)J/ApJ/860/65 : MegaCam survey of outer halo satellites. I. (Munoz+, 2018)J/ApJ/863/25 : Magellan/Megacam obs. of 4 MW satellites (Mutlu-Pakdil+, 2018)J/ApJ/870/83 : Abundances in ultra-faint dwarf gal. GruI & TriII (Ji+, 2019)J/ApJ/893/47 : MW satellite census. I. DES & PS1 (Drlica-Wagner+, 2020)J/ApJ/913/53 : Gas content of dwarf gal. within 2Mpc of MW (Putman+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/916/81https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/916/81http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/916/81https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/916/81https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/916/81http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/916/81GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/916/81/table3 (The final calibrated stellar catalog for Grus I)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/916/81/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/916/81/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/916/81/table3?GETtext/xml+votable180.050000true344.174-50.3670.005555555555555556Cone search capability for table J/ApJ/916/81/table4 (The final calibrated stellar catalog for Indus II)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/916/81/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/916/81/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/916/81/table4?GETtext/xml+votable180.050000true309.997-46.3650.0055555555555555566/46279 46290 47425 47427-47428https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/916/81?format=asciiOpticaldefaultJ/ApJ/916/81/table3The final calibrated stellar catalog for Grus IrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintID[67/122349592] Stellar identifiermeta.id;meta.mainlongRAJ2000[343.85/344.51] Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-50.37/-49.95] Declination (J2000)degpos.eq.dec;meta.maingmag[15.58/27] Apparent DES g band magnitudemagphot.mag;em.opt.Bfloate_gmag[0/0.3] Uncertainty in gmagmagstat.error;phot.magfloatrmag[15.17/26.67] Apparent DES r band magnitudemagphot.mag;em.opt.Rfloate_rmag[0/0.3] Uncertainty in rmagmagstat.error;phot.magfloatJ/ApJ/916/81/table4The final calibrated stellar catalog for Indus IIe_gmag[0/0.3] Uncertainty in gmagmagstat.error;phot.magfloatrmag[14.75/27.07] Apparent DES r band magnitudemagphot.mag;em.opt.Rfloate_rmag[0/0.3] Uncertainty in rmagmagstat.error;phot.magfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintID[6/174663982] Stellar identifiermeta.id;meta.mainlongRAJ2000[309.41/310.02] Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-46.37/-45.95] Declination (J2000)degpos.eq.dec;meta.maingmag[15.18/27.08] Apparent DES g band magnitudemagphot.mag;em.opt.Bfloat