Planck CollaborationAde, P. A. R.P. A. R.AdeAghanim, N.N.AghanimNatoli, PaoloPaoloNatoliPolenta, GianlucaGianlucaPolenta2020-09-172020-09-172011-12-01https://hdl.handle.net/20.500.13025/2118Astronomy & Astrophysics, Volume 536, id.A8, <NUMPAGES>28</NUMPAGES> pp.We present the first all-sky sample of galaxy clusters detected blindly by the Planck satellite through the Sunyaev-Zeldovich (SZ) effect from its six highest frequencies. This early SZ (ESZ) sample is comprised of 189 candidates, which have a high signal-to-noise ratio ranging from 6 to 29. Its high reliability (purity above 95%) is further ensured by an extensive validation process based on Planck internal quality assessments and by external cross-identification and follow-up observations. Planck provides the first measured SZ signal for about 80% of the 169 previously-known ESZ clusters. Planck furthermore releases 30 new cluster candidates, amongst which 20 meet the ESZ signal-to-noise selection criterion. At the submission date, twelve of the 20 ESZ candidates were confirmed as new clusters, with eleven confirmed using XMM-Newton snapshot observations, most of them with disturbed morphologies and low luminosities. The ESZ clusters are mostly at moderate redshifts (86% with z below 0.3) and span more than a decade in mass, up to the rarest and most massive clusters with masses above 1 10<SUP>15</SUP> M<SUB>&sun;</SUB>. Corresponding author M. Douspis, e-mail marian.douspis@ias.u-psud.frAppendix is available in electronic form at <A href="http //www.aanda.org">http //www.aanda.org</A>cosmology observationsgalaxies clusters generalcatalogs10.1051/0004-6361/201116459http://adsabs.harvard.edu/abs/2011A&A...536A...8P2011A&A...536A...8P