276/292/300 & 5AB 20:59:20.57 & $+$00:00:33.4 & 17.853 & usdM2.5 & 11Aug2012 & 1.12 & 266/266/290 & 5AB 10:41:07.20 & $+$06:33:04.7 & 18.062 & usdM3.0 & 31May2013 & 1.27 & 246/262/270 & 5AB 15:35:40.74 & $+$08:21:43.3 & 18.008 & usdM4.0 & 10Aug2013 & 1.21 & 276/292/300 & 5AB 14:17:48.62 & $+$07:11:05.4 & 17.658 & usdM4.5 & 12Jul2013 & 1.18 & 276/292/300 & 5AB 12:04:26.91 & $+$13:29:23.3 & 16.549 & usdM5.0 & 12Jun2012 & 1.33 & 216/216/240 & 2AB 16:27:54.22 & $+$00:37:14.0 & 18.384 & usdM5.5 & 17Aug2012 & 1.15 & 266/266/290 & 5AB 16:41:23.73 & $+$24:49:42.4 & 17.233 & usdM6.0 & 15Jul2013 & 1.58 & 126/142/150 & 3AB 08:22:33.69 & $+$17:00:19.9 & 17.300 & usdM7.5 & 03Apr2013 & 1.39 & 126/142/150 & 3AB 12:27:05.06 & $-$04:47:20.7 & 16.630 & usdM8.5 & 11Jul2013 & 1.35 & 126/142/150 & 3AB \[tab\_MplusTeff\_sdM:log\_obs\_Xshooter\]

BT-Settl synthetic spectra {#MplusTeff_sdM:Models}
==========================

To infer the range of physical parameters (gravities i.e. $\log$(g), metallicities \[M/H\], and T$_{\rm eff}$) for our sequence of subdwarfs, we employed the BT-Settl models [@allard03a; @allard07a; @allard10a; @allard11; @allard12] available for retrieval at France Allard’s webpage[^4]. The BT-Settl models account for TiO [@plez98; @plez08] and H$_{2}$O ([@barber06a] among other opacities using the @caffau11a abundance values 