Swift/BAT detects an outburst from an X-ray transient in the globular cluster Terzan 5
ATel #7240; D. Altamirano (Southampton), H. A. Krimm (CRESST/GSFC/USRA), A. Patruno (Leiden), A. Bahramian, C. O. Heinke (Alberta), R. Wijnands (Amsterdam), N. Degenaar (Cambridge)
on 17 Mar 2015; 17:54 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Diego Altamirano (d.altamirano@soton.ac.uk)
Subjects: X-ray, Globular Cluster, Transient
A rate increase from the direction of Terzan 5 was detected in the BAT
hard X-ray transient monitor starting on 2015 March 13 (MJD 57094).
The flux has been rising and has reached 0.007 +/- 0.001 ct s^-1 cm^-2
(~30 mCrab; 15-50 keV) on 2015 March 16. This is the brightest this
source has been since mid-2012, when it peaked above 120 mCrab. The
BAT result is based on the coordinates of EXO 1745-248 (RA = 267.022
deg ; Dec= -24.780 deg). The BAT angular resolution of ~3 arc minutes is
not sufficiently precise to distinguish this source from another
object in the Terzan 5 region. The BAT light curve can be found here:
http://swift.gsfc.nasa.gov/results/transients/weak/EXO1745-248/
Terzan 5 is known to have at least three neutron star low-mass X-ray
binaries, all of them transient (e.g. Bahramian et al. 2014, ApJ, 780,
127, and references therein). Swift target of opportunity observations
have been approved to confirm the Swift/BAT detection, and to test
whether the the coordinates are consistent with a new X-ray transient
or any of the three known transients.
