2009ApJ...701.1627H

We have identified two moderately bright, rapidly variable transients in new and archival X-ray data near the Galactic center. Both objects show strong, flaring variability on timescales of tens to thousands of seconds, evidence of N_Hvariability, and hard spectra. XMMU J174445.5-295044 is seen at 2-10 keV fluxes of 3x10^–11 to <10^–12 erg/cm2/s, with N_H at or above 5x10²²/cm2, by XMM-Newton, Chandra, and Suzaku. A likely Two Micron All Sky Survey (2MASS) counterpart with K_S= 10.2 shows colors indicative of a late-type star. CXOU J174042.0-280724 is a likely counterpart to the fast hard transient IGR J17407-2808. Chandra observations find F_X(2-10 keV) ∼10^–12 erg/cm2/s, with large N_Hvariations (from 2x10²² to >2x10²³/cm2). No 2MASS counterpart is visible, to K_S>13. XMMU J174445.5-295044 seems likely to be a new symbiotic star or symbiotic X-ray binary, while CXOU J174042.0-280724 is more mysterious, likely an unusual low-mass X-ray binary.