Table 5:

Summary of confirmed and candidate WNLh binaries in young open clusters.

Cluster	Age	Total	RV	Binaries
	(Myr)		survey	Confirmed	Candidates
NGC3603	1.3  0.3	3	3	2	0
Carina	1.5  0.5	3	3	2	0
HM-1	2.2  0.5	2	0	-	0
NGC6231	2.7  0.5	1	0	-	0
Arches	2.5  0.5	13	0	-	3
Wd 2	2.6  0.2	2	1	1	1
Bochum 7	2.8  0.5	1	1	1	0
R136/30 Dor	>2	23	23	8	1
Total		48	31	14	5

The cluster list follows that of Crowther et al. (2006), supplemented with the WNLh rich Arches (Figer et al. 2002) and 30 Dor (Walborn & Blades 1989) clusters. Column 4 summarises the number of stars in each cluster for which a RV survey has been carried out. Confirmed binaries were identified via photometric or spectroscopic evidence, while candidate binaries were selected if  erg s^-1 and/or kT >4 keV, noting that such strict criteria would exclude known spectroscopic binaries such as WR20a and WR22 (Table 4). Given the different sensitivities of current RV and X-ray surveys (e.g. Pollock 1987; Pollock et al. 1995; Ignace et al. 2000; Oskinova 2005) we present results for individual clusters.