\begin{table}%t4
\caption{\label{fields-cat}Format of ISOGAL "Fields'' Table (version 1) -- 263
entries (see example in Table~\ref{fields-cat_ex}).}
%\centerline
{\begin{tabular}{rllll}
\hline\hline
Col. & Name & Format & Units [range] & Description \\
\hline
 1 & Name      & a14  &                  & ISOGAL field identifier \\
 2 & ION7      & a8   &                  & ION for 7~$\mu$m data (see
Table~\ref{ISO-obs}) \\
 3 & ION15     & a8   &                  & ION for 15~$\mu$m data \\
 4 & filt7     & i1   & [2,5,6]          & 7~$\mu$m filter \\
 5 & filt15    & i1   & [3,9]            & 15~$\mu$m filter \\
 6 & pfov      & i1   & arcsec  [3,6]    & pixel field of view \\
 7 & G\_lon    & f8.4 & deg [$-180$--+180] & Galactic longitude of field centre \\
 8 & G\_lat    & f8.4 & deg [$-90$--+90]   & Galactic latitude of field centre \\
 9 & $dl$        & f6.4 & deg              & half width of field in
longitude$^a$\\
10 & $db$        & f6.4 & deg              & half width of field in
latitude$^a$ \\
11 & area      & f6.4 & deg$^2$          & area of field \\
12 & dens7     & i5   & deg$^{-2}$       & density of 7~$\mu$m sources \\
13 & dens15    & i5   & deg$^{-2}$       & density of 15~$\mu$m sources \\
14 & RMS\_II   & f4.2 & arcsec           & RMS separation of 7--15~$\mu$m associated
sources \\
15 & RMS\_ID   & f4.2 & arcsec           & RMS separation of ISO-DENIS associated
sources \\ 
16 & $K$\_max1   & f4.1 &~mag              & DENIS $K_{\rm s}$~magnitude cutoff
1$^b$ \\
17 & $K$\_max2   & f4.1 &~mag              & DENIS $K_{\rm s}$~magnitude cutoff
2$^c$ \\
18 & dens\_K2  & i5   & deg$^{-2}$       & density of DENIS $K_{\rm s}$ sources
used$^d$ \\
\hline
\end{tabular}}
\smallskip
$^a$~{$dl$ and $db$ apply to the limits inside the edges of
the images within which sources are accepted.} \\
$^b$~{maximum DENIS $K_{\rm s}$~magnitude limiting the density of $K_{\rm s}$ DENIS
sources to $\sim$18~000 sources per square degree if the ISO images have 6\arcsec\
pixels (or to $\sim$72~000 sources per square degree for the 3\arcsec\ ISO
observations). $K$\_max1 is used to discuss the quality of ISOGAL--DENIS
associations (see Sect.~\ref{sec-flagID}).}\\
$^c$~{maximum DENIS $K_{\rm s}$~magnitude accepted in order to avoid spurious
cross-identifications. The density of $K_{\rm s}$ DENIS sources is limited to
$\sim$36~000 sources per square degree for 6\arcsec\ ISO observations (and again
to $\sim$72~000 sources per square degree for 3\arcsec\ ISO observations).}\\
$^d$~{density of DENIS $K_{\rm s}$-band sources brighter than the cutoff
magnitude $K$\_max2.}
\end{table}