The XMM Cluster Survey ( XCS ) is a serendipitous search for galaxy clusters using all publicly available data in the XMM–Newton Science Archive .
Its main aims are to measure cosmological parameters and trace the evolution of X-ray scaling relations .
In this paper we present the first data release from the XMM Cluster Survey ( XCS-DR1 ) .
This consists of 503 optically confirmed , serendipitously detected , X-ray clusters .
Of these clusters , 255 are new to the literature and 356 are new X-ray discoveries .
We present 464 clusters with a redshift estimate ( 0.06 < z < 1.46 ) , including 261 clusters with spectroscopic redshifts .
In addition , we have measured X-ray temperatures ( T _ { X } ) for 402 clusters ( 0.4 < T _ { X } < 14.7 keV ) .
We highlight seven interesting subsamples of XCS-DR1 clusters : ( i ) 10 clusters at high redshift ( z > 1.0 , including a new spectroscopically-confirmed cluster at z = 1.01 ) ; ( ii ) 67 clusters with high T _ { X } ( > 5 keV ) ; ( iii ) 131 clusters/groups with low T _ { X } ( < 2 keV ) ; ( iv ) 27 clusters with measured T _ { X } values in the SDSS ‘ Stripe 82 ’ co-add region ; ( v ) 78 clusters with measured T _ { X } values in the Dark Energy Survey region ; ( vi ) 40 clusters detected with sufficient counts to permit mass measurements ( under the assumption of hydrostatic equilibrium ) ; ( vii ) 105 clusters that can be used for applications such as the derivation of cosmological parameters and the measurement of cluster scaling relations .
The X-ray analysis methodology used to construct and analyse the XCS-DR1 cluster sample has been presented in a companion paper , ( ) .