\begin{table}%t5
%\centering
\par
\caption{\label{CPU_memory_with_sigma}Variation in CPU time and memory requirements with the
 oversampling factor $\sigma$ for simulating a realization CMB
 map (both unlensed and lensed, nside = 1024, $l_{\max}=2048$) using NFFT.}
\begin{tabular}{cccc}
\hline \hline
Oversampling&
Convolution&
CPU&
Memory
\\
factor&
length&
time&
requirement
\\
$\left(\sigma\right)$&
$\left(K\right)$&
&
\\
\hline 
2&
4&
32 min&
7.6 GB
\\
%\hline 
3&
4&
38 min&
10 GB
\\
%\hline 
4&
4&
47 min&
13 GB
\\
\hline
\end{tabular}
\end{table}