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ATEL # 2258; C. B. Markwardt (U. Maryland & NASA/GSFC), J. H. Swank (NASA/GSFC), S. D. Barthelmy (NASA/GSFC), W. H. Baumgartner (UMBC & NASA/GSFC), D. N. Burrows (PSU), P. A. Evans (U. Leicester), S. T. Holland (USRA & NASA/GSFC), E. A. Hoversten (PSU), K. L. Page (U. Leicester)
on 24 Oct 2009; 18:02 UT
Distributed as an Instant Email Notice (Transients)
Password Certification: Craig B. Markwardt (firstname.lastname@example.org)
Subjects: X-ray, Gamma Ray, Request for Observations, Binaries, Black Holes, Neutron Stars, Transients
Referred to by ATEL #: 2259, 2261, 2263, 2265, 2268, 2269
On 2009-10-23 at 19:55 UT, RXTE discovered a new source while scanning the galactic bulge region, designated XTE J1752-223. Based on the existing PCA scan data, the best fit position is, R.A. = 268.05(16), Dec. = -22.31(4) (J2000), with estimated 95% uncertainty of the final digits shown in parentheses.
The 2-10 keV flux of the source at that time was about 30 mCrab. In the past six months, no source has been detected at that position with 95% upper limit of about 1 mCrab. There are no obvious signatures of fast variability (i.e. no pulsations) in the limited amount of PCA scan data available. (1 mCrab = 2.4e-11 erg/cm/s^2, 2-10 keV)
On 2009-10-24 at 14:18:50 UT, the Swift BAT instrument triggered and located the source. The on-board calculated location is R.A. = 268.044, Dec. = -22.325 (J2000), with 90% position uncertainty of about 3 arcmin. The RXTE PCA and Swift BAT positions are consistent. Swift did not slew immediately to the source location because of a Moon observing constraint, so prompt X-ray or UV/optical data are not available yet. Given the sensitivity of the BAT, the approximate 15-150 keV source flux is about 100 mCrab.
Additional follow-up observations by RXTE and Swift have been requested.