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ATEL # 1442; C. B. Markwardt (U.Md./CRESST/NASA GSFC), J. H. Swank (NASA GSFC)
on 27 Mar 2008; 0:58 UT
Password Certification: Craig B. Markwardt (firstname.lastname@example.org)
Subjects: X-ray, Binaries, Black Holes, Neutron Stars, Transients
Referred to by ATEL #: 1451
RXTE PCA scans of the galactic bulge region on 2008-03-21 at 17:20 UTC found a new source, with a flux of about 5 mCrab (2-10 keV). A dedicated scanning observation on 2008-03-25 at 20:36 UTC further refined the position to be (RA,Dec) = 259.889, -29.060 (J2000) with 95% position error of 7 arcminutes. This region is relatively free of nearby confusing sources, so the position fit should be reliable. No obvious counterparts were found after searching Simbad as well as previous X-ray databases.
The regular PCA monitoring observations have already recorded a decline in flux. The recorded 2-10 keV fluxes were 1.3, 2.8, 4.9, 1.6 mCrab on Mar 15.1, 18.1, 21.7 and 25.7 respectively, with uncertainties of about 0.6 mCrab.
The X-ray spectrum based on a pointed PCA observation on 2008-03-24 was consistent with a power law, with photon index 2.1 ± 0.1. Thus, the fluxes in mCrab should be comparable in other energy bands. The absorbing column density was unconstrained by the fit.