$-$
         $\sigma$ Orionis 51                    M9             $>$M9.5          $>$M9.5           L0$\pm$0.5
         $\sigma$ Orionis 71                    L0              M7.8             M8.3             M8$\pm$0.5
     $\sigma$ Orionis J053$-$024               M9.5             M8.1             M9.3            M8.75$\pm$0.5
              KPNO-Tau 1                       M8.5             M8.3             M9.1            M8.75$\pm$0.5
              KPNO-Tau 4                       M9.5            $>$M9.5          $>$M9.5           L0$\pm$0.5
             KPNO-Tau 12                        M9              M9.1             M9.3            M9.25$\pm$0.5
              0457+3015                       M9.25             M9.1             M9.4            M9.25$\pm$0.5
          \[1ex\] 152$-$717                     M9             $>$M9.5           M9.3            M9.5$\pm$1.0
   \[1ex\] $^{1}$Old field objects.                                                             
  ---------------------------------- ------------------------ --------- ----------------------- ---------------

\[tab:tab4\]

Spectral Typing
---------------

We took this opportunity to use our higher resolution spectra to re-examine the spectral typing of the younger objects in our sample, including the PMO. We used the WK and QK spectral indices previously defined by our group (L06), and the fits to these spectral indices used to characterise the GNIRS and NIRI data in L06 (W09). These indices provide spectral types consistent with the Luhman system of optical classification of spectra [@luhman99]. QK is a reddening independent index, whereas WK requires knowledge of the extinction toward the source. For the PMO 152$-$717, the extinction A$_V$ = 3.7 (L06). Thus, we were able to use the dereddened spectrum in determining its spectral type. For the $\sigma$ Orionis objects it is known that A$_V$ $\leq$ 1 mag, and, in most cases, changing A$_V$ by $\pm$ 2 mag 