fixed to the cluster value, due to ’s relative insensitivity to $N_H$. All our reported $L_X$ values are for 0.5-10 keV (for consistency with other instruments; this extrapolation may incur additional systematic errors), and assume a distance of 8.5 kpc.

The July 30 pointed observation could be fit with an absorbed power-law with photon index 2.2$\pm0.1$, and a luminosity of $5\pm1\times10^{35}$ , 3.5 times lower than the July 28  observation (Table 1; but see below). The August 30 observation showed a photon index of 1.84$\pm0.02$ and $L_X=2.9\times10^{36}$ . The series of observations on Sept. 1 and 2 showed much lower fluxes, averaging $L_X=4\times10^{35}$ ; the longest also shows clear evidence of an iron line at 6.7$\pm0.2$ keV. However, simultaneous  observations (see below) find much lower fluxes from the cluster of $6\times10^{34}$ , consistent with the quiescent cluster emission and inconsistent with the transient position. Therefore we attribute the /PCA flux observed on Sept. 1 to the Galactic Ridge emission at this location. Subtracting this flux from the July 30 /PCA measurement gives $L_X=1\pm1\times10^{35}$ , a very marginal detection, and makes its spectral parameters unreliable.

We refine our spectral fitting of the August 30 observation, by extracting spectra from only the 