\begin{table}%t1 
\caption{\label{tab:obs}Observations for the analysis
of the three X-ray transients: TR1 (XMMU J004215.8+411924), 
TR2 (SWIFT J004217.4+411532), and TR3 (M31N 2006-11a).
}
\small%\centerline
{
\begin{tabular}{llccccccc}
\hline\hline
Observation &Date & Observatory & Instrument & Obs-ID & TR1 & TR2 & TR3\\
\hline
1 &2006 Jun. 05 & Chandra & HRC-I & 7283       & -- & -- & --\\
2 &2006 Jul. 02 & XMM     & EPIC  & 0405320501 & -- & -- & --\\
3 &2006 Jul. 31 & Chandra & ACIS-I& 7139       & + & -- & --\\	
4 &2006 Aug. 09 & XMM     & EPIC  & 0405320601 & + & -- & --\\
5 &2006 Sep. 01 & Swift   & XRT   & 00030802001& + & + & --\\
6 &2006 Sep. 11 & Swift   & XRT   & 00030804001& -- & + & --\\
7 &2006 Sep. 24 & Chandra & ACIS-I& 7140     &--&+& \\
8 &2006 Sep. 30 & Chandra & HRC-I & 7284	   & -- & + & --\\
9 &2006 Nov. 13 & Chandra & HRC-I & 7285       & -- & + & --\\
10& 2006 Dec. 4 & Chandra & ACIS-I & 7064 &  & + & \\
11&2006 Dec. 31 & XMM     & EPIC  & 0405320701 & -- & + & --\\
12&2007 Jan. 16 & XMM     & EPIC  & 0405320801 & -- & + & --\\
13&2007 Mar. 11 & Chandra & HRC-I & 7286       & -- & -- & --\\
14&2007 Jun. 01 & Swift   & XRT   & 00035336001& -- & -- & +\\
15&2007 Jul. 12 & Swift   & XRT   & 00030968001& -- & -- & --\\
16&2007 Jul. 13 & Swift   & XRT   & 00030968002& -- & -- & --\\
17&2007 Jul. 18 & Swift   & XRT   & 00030968004& -- & -- & --\\
\hline
\end{tabular}}
\smallskip
Note: a
+ signifies that the source was detected in this observation, whereas
a -- signifies that it was not detected.
\end{table}