J/A+A/711/A38ivo://CDS.VizieR/J/A+A/711/A38CDSDuffy C.Cappellaro E.Botticella M.T.Hook I.M.Poidevin F.,Moriya T.J.Chrimes A.A.Petrecca V.Paterson K.Goobar A.Galbany L.,Kotak R.Gall C.Gutierrez C.M.Tao C.Izzo L.Aghanim N.Altieri B.,Amara A.Andreon S.Auricchio N.Baccigalupi C.Baldi M.Balestra A.,Bardelli S.Basset A.Battaglia P.Biviano A.Bonchi A.Branchini E.,Brescia M.Brinchmann J.Camera S.Capobianco V.Carbone C.,Carretero J.Casas R.Casas S.Castellano M.Castignani G.Cavuoti S.,Cimatti A.Colodro-Conde C.Congedo G.Conselice C.J.Conversi L.,Copin Y.Courbin F.Courtois H.M.Cropper M.Da Silva A.Degaudenzi H.,De Lucia G.Di Giorgio A.M.Dolding C.Dole H.Dubath F.Duncan C.A.J.,Dupac X.Dusini S.Ealet A.Escoffier S.Farina M.Faustini F.,Ferriol S.Fotopoulou S.Frailis M.Franzetti P.Galeotta S.George K.,Gillis B.Giocoli C.Gomez-Alvarez P.Grazian A.Grupp F.Gwyn S.,Haugan S.V.H.Hoar J.Hoekstra H.Holmes W.Hormuth F.Hornstrup A.,Hudelot P.Jahnke K.Jhabvala M.Keihanen E.Kermiche S.Kubik B.,Kuijken K.Kummel M.Kunz M.Kurki-Suonio H.Le Boulc'h Q.,Le Brun A.M.C.Le Mignant D.Liebing P.Ligori S.Lilje P.B.,Lindholm V.Lloro I.Maino D.Maiorano E.Mansutti O.Marcin S.,Marggraf O.Martinelli M.Martinet N.Marulli F.Massey R.,Medinaceli E.Melchior M.Mellier Y.Meneghetti M.Merlin E.Meylan G.,Moresco M.Morris P.W.Moscardini L.Neissner C.Nichol R.C.,Niemi S.-M.Nightingale J.W.Padilla C.Paltani S.Pasian F.,Pedersen K.Percival W.J.Pettorino V.Pires S.Polenta G.Poncet M.,Popa L.A.Raison F.Rebolo R.Renzi A.Rhodes J.Riccio G.Romelli E.,Roncarelli M.Saglia R.Sakr Z.Sapone D.Sartoris B.,Schewtschenko J.A.Schirmer M.Schneider P.Schrabback T.Secroun A.,Seidel G.Serrano S.Simon P.Sirignano C.Sirri G.Skottfelt J.,Stanco L.Steinwagner J.Tallada-Crespi P.Taylor A.N.Tereno I.,Toledo-Moreo R.Torradeflot F.Tutusaus I.Valenziano L.Vassallo T.,Verdoes Kleijn G.Wang Y.Weller J.Zacchei A.Zamorani G.Zerbi F.M.,Zucca E.Burigana C.Cabanac R.Gabarra L.Scottez V.Scott D.,Sullivan M.2026-06-30T15:45:38Z2026-06-30T16:45:12ZCDS support team

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

cds-question@unistra.frsupernovaeinfrared-photometryvisible-astronomyWe report on serendipitous Euclid observations of previously known transients, using the Euclid Q1 data release. By cross-matching with the Transient Name Server (TNS) we identify 164 transients that coincide with the data release. Although the Euclid Q1 release only includes single- epoch data, we are able to make Euclid photometric measurements at the location of 161 of these transients. Euclid obtained deep photometric measurements or upper limits of these transients in the IE, YE, JE, and HE bands at various phases of the transient light-curves, including before, during, and after the observations of ground-based transient surveys. Approximately 70% of known transients reported in the six months before the Euclid observation date and with discovery magnitude brighter than 24 were detected in Euclid IE images. Our observations include one of the earliest near-infrared detections of a Type Ia supernova (SN 2024pvw) 15 days prior to its peak brightness, and the late-phase (435.9 days post peak) observations of the enigmatic core-collapse SN 2023aew. Euclid deep photometry provides valuable information on the nature of these transients such as their progenitor systems and power sources, with late time observations being a uniquely powerful contribution. In addition, Euclid is able to detect the host galaxies of some transients that were previously classed as hostless. The Q1 data demonstrate the power of the Euclid data even with only single-epoch observations available, as will be the case for much larger areas of sky in the Euclid Wide Survey.2026A&A...711A..38Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/711/A38CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/388 : Euclid final merged catalog. Q1 data releaseJ/A+A/711/A10 : Euclid (Q1). Census of dwarf galaxies (Euclid Coll., 2026)J/A+A/711/A16 : X-ray point-like sources of Euclid (Q1) (Euclid Coll.+, 2026)J/A+A/711/A37 : Ultracool dwarfs in Euclid Deep Fields (Zerjal+, 2026)J/A+A/711/A38 : Euclid Q1. Photometric studies of known transientsJ/A+A/711/A39 : Euclid Q1. Secondary nuclei in ET galaxies (Fabricius+, 2026)J/A+A/711/A20 : Galaxies of Euclid (Q1) (Euclid Coll.+, 2026)J/A+A/711/A24 : Euclid Q1. Little red dots properties (Euclid Coll., 2026)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/711/A38https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/711/A38http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/711/A38https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/711/A38https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/711/A38http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/711/A38GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/711/A38/catalog (Complete catalogue of sources considered in the paper (table A1))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/711/A38/catalog?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/711/A38/catalog?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/711/A38/catalog?GETtext/xml+votable180.050000true58.53102083-47.843055560.0055555555555555565/2559 2901 3839 4010 8983 8989 6/10230-10231 11603 11612-11613 15355 16044 16046-16047 33982-33983 34026 34311 34321 34325 34327 34330-34331 34341 34352 34376 35931 35953 36106https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/711/A38?format=asciiOpticalInfrareddefaultJ/A+A/711/A38/catalogComplete catalogue of sources considered in the paper (table A1)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource name (AT NNNNaaaa or SN YYYYaaaa)meta.id;meta.maincharRAJ2000TNS right ascension (J2000)pos.eq.ra;meta.mainDEJ2000TNS declination (J2000)pos.eq.dec;meta.mainMJD? Modified Julian date with VIS instrumentdtime.epochdoublenullablel_IEmagLimit flag on VISmagmeta.code.errorcharIEmag? VIS I_E_ band magnitudemagphot.mag;em.optfloatnullablee_IEmag? VIS I_E_ band magnitude errormagstat.error;phot.magfloatnullabledistIE? Separation between the TNS reported position and the location of the source in I_E_arcsecpos.angDistancefloatnullableNotes[1/7]? Notes (1)meta.noteintnullablel_YEmagLimit flag on Ymagmeta.code.errorcharYEmag? NIR Y_E_ band magnitudemagphot.mag;em.IR.Jfloatnullablee_YEmag? NIR Y_E_ band magnitude errormagstat.error;phot.magfloatnullabledistYE? Separation between the TNS reported position and the location of the source in Y_E_arcsecpos.angDistancefloatnullablel_JEmagLimit flag on Jmagmeta.code.errorcharJEmag? NIR J_E_ band magnitudemagphot.mag;em.IR.Jfloatnullablee_JEmag? NIR J_E_ band magnitude errormagstat.error;phot.magfloatnullabledistJE? Separation between the TNS reported position and the location of the source in J_E_arcsecpos.angDistancefloatnullablel_HEmagLimit flag on Hmagmeta.code.errorcharHEmag? NIR H_E_ band magnitudemagphot.mag;em.IR.Hfloatnullablee_HEmag? NIR H_E_ band magnitude errormagstat.error;phot.magfloatnullabledistHE? Separation between the TNS reported positionarcsecpos.angDistancefloatnullable