Table 1: Properties of the observational sample commonly used to test deep crustal heating. The temperature quoted for Aql X-1 is the redshifted $T_{\rm S}^\infty$ . We use $T_{\rm S}=T_{\rm S}^\infty /(1-2GM/R)^{1/2}$ with the canonical M/R=0.2. For Cen X-4 we quote the temperatures from both Rutledge et al. (2001) and Campana et al. (2004).
Source $kT_{\rm S}$ [eV] R $\langle\dot{m}\rangle$ $[M_\odot~{\rm yr}^{-1}]$ Reference

Aql X-1 113⁺³_-4 13.2 10^-10 Rutledge et al. (2002a); Yakovlev et al. (2003)

Cen X-4 76 $\pm$ 7, 85 $\pm$ 3 12.9 $1.9\times 10^{-11}$ Tomsick et al. (2004); Campana et al. (2004); Rutledge et al. (2001)

4U 1608-522 170 $\pm$ 30 9.4 $6.9\times 10^{-11}$ Tomsick et al. (2004); Rutledge et al. (1999)

SAX J1808.4-3658 <54 - $5\times 10^{-12}$ Campana et al. (2002); Yakovlev & Pethick (2004)

SAX J1810.8-2609 <72 - $1.7\times 10^{-12}$ Tomsick et al. (2004); Jonker et al. (2004)

XTE J2123-058 <66 - $2.9\times 10^{-12}$ Tomsick et al. (2004)

XTE J1709-267 $116 \pm 2$ - $1.2\times 10^{-10}$ Jonker et al. (2004,2003)

**Table 1:** Properties of the observational sample commonly used to test deep crustal heating. The temperature quoted for Aql X-1 is the redshifted $T_{\rm S}^\infty$ . We use $T_{\rm S}=T_{\rm S}^\infty /(1-2GM/R)^{1/2}$ with the canonical M/R=0.2. For Cen X-4 we quote the temperatures from both Rutledge et al. (2001) and Campana et al. (2004).
Source	$kT_{\rm S}$ [eV]	R	$\langle\dot{m}\rangle$ $[M_\odot~{\rm yr}^{-1}]$	Reference
Aql X-1	113⁺³_-4	13.2	10^-10	Rutledge et al. (2002a); Yakovlev et al. (2003)
Cen X-4	76 $\pm$ 7, 85 $\pm$ 3	12.9	$1.9\times 10^{-11}$	Tomsick et al. (2004); Campana et al. (2004); Rutledge et al. (2001)
4U 1608-522	170 $\pm$ 30	9.4	$6.9\times 10^{-11}$	Tomsick et al. (2004); Rutledge et al. (1999)
SAX J1808.4-3658	<54	-	$5\times 10^{-12}$	Campana et al. (2002); Yakovlev & Pethick (2004)
SAX J1810.8-2609	<72	-	$1.7\times 10^{-12}$	Tomsick et al. (2004); Jonker et al. (2004)
XTE J2123-058	<66	-	$2.9\times 10^{-12}$	Tomsick et al. (2004)
XTE J1709-267	$116 \pm 2$	-	$1.2\times 10^{-10}$	Jonker et al. (2004,2003)