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C. Markwardt (U. Maryland & NASA/GSFC)
Programs with the RXTE ASM, PCA and BeppoSAX WFC are finding new ways to monitor the X-ray sky. We present results from RXTE monitoring observations of the galactic bulge, derived from twice weekly PCA raster scans over the region within about 15\circ from the galactic center. We have discovered several new, fainter, and faster evolving transients, compared to the ``canonical'' soft X-ray transients. Many of these sources also do not follow the ``FRED'' time evolution --- fast rise, exponential decay --- which is typical for brighter transients, but instead exhibit extreme variability (e.g. by factors of >10 within a few days). This trend suggests that intrinsically fainter sources are indeed more variable and vary more quickly. The PCA monitoring observations are the most sensitive to faint sources, compared to the ASM and WFC, but are not likely to observe very fast phenomena like X-ray bursts and cover less of the sky. Several trade-offs like this are involved in constructing a future X-ray sky monitoring program, which I will discuss.