\begin{table}%t3
\caption{WFCAM performance.}\label{tab3}
%\centering
\small
\begin{tabular}{l l l}
\hline\hline
Item		& Specification	& Units and notes  \\
\hline
Average detector QE & 0.54, 0.62, 0.61  & In $J,H,K$, and averaged over 4 devices \\
Focal plane Coplanarity	& 50	& $\mu$m peak-to-valley over 4 devices\\
IR Pixel clock rate & 187 & kHz \\
Focal plane readout time & 0.7 & Seconds. Includes extra reset for stability\\ 
Read noise & $<$30 & Electrons in correlated double sample mode \\
Median delivered image quality & 0.7 & Arcseconds. $K$-band {\it FWHM}. Near zenith\\
Best delivered image quality & 0.55 & Arcseconds. $K$-band {\it FWHM}. Near zenith\\
Astrometric errors & $<$0.1 & Arcseconds over full field of view, after\\
				&	& correction for field distortion \\
Field distortion & $0.3 \%$ & Centre-to-corner change in plate scale\\
Systematic photometric errors & $<$0.02 & Magnitudes. Over the field of view\\
Total system throughput in Z,Y,J,H,K & 0.14, 0.16, 0.20, 0.28, 0.29 & including telescope, filter and detector QE\\
 & & Relative to a perfect telescope and instrument \\
 &  & of 10.5 sq. m collecting area \\
Autoguider magnitude limit & 17 & $I$ band at 40 Hz. No moon \\
WFCAM average observing efficiency & 0.55 & (time spent integrating)/(elapsed time)\\
\hline
\end{tabular}
\end{table}