  Recent observations with the XMM-Newton satellite confirmed the existence of
the soft excess phenomenon in galaxy clusters, earlier discovered in several
EUVE, ROSAT and BeppoSAX observations. Among the clusters for which XMM has
reported detection of soft excess emission are MKW03s and A2052, two clusters
in the Hercules concentration.
  The Hercules supercluster lies along the southern extension of the North
Polar Spur, a region of bright soft X-ray emission clearly visible in ROSAT
All-Sky Survey images. We analyze 11 pointed ROSAT PSPC observations toward 3
clusters in the Hercule concentration, MKW03s, A2052 and A2063, and 8
neighboring fields in order to investigate the soft X-ray emission in that
region of the sky. We find that the soft X-ray emission varies by a factor of
few on scales of few degrees, rendering the background subtraction a complex
task. If the Noth Polar Spur emission is of local origin, we find that only
A2052 and A2063 have evidence of cluster soft excess emission, and that the
OVII emission lines detected in XMM observations of A2052 and MKW03s are not
associated with the cluster. If part or all of the North Polar Spur soft X-ray
enhancement is of extragalactic nature, the three clusters feature strong soft
excess emission, and the OVII emission lines observed by XMM are genuinely
associated with the clusters.
  We interpret the soft excess emission with the presence of warm gas, either
intermixed with the hot intra-cluster medium or in filamentary structures
located around the clusters, and estimate that the warm gas is approximately as
massive as the hot intra-cluster medium.
