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Chandra Identification of the 2011 Transient in Terzan 5: Same as the 2000 Transient

ATel #3743; D. Pooley (Sam Houston State U., Eureka Scientific), J. Homan (MIT), D. Altamirano (U. Amsterdam), N. Degenaar (U. Amsterdam), C. O. Heinke (U. Alberta), W. Lewin (MIT), G. R. Sivakoff (U. Alberta), R. Wijnands (U. Amsterdam)
on 7 Nov 2011; 14:57 UT
Credential Certification: dave pooley (dave@mit.edu)

Subjects: X-ray, Binary, Globular Cluster, Neutron Star, Transient

Referred to by ATel #: 4242

We triggered a Chandra ToO observation of the ongoing outburst of a transient source in the globular cluster Terzan 5 (ATel #3714, #3718, #3720, #3723, #3729). The 9.8 ks observation was taken with the ACIS S3 chip in imaging mode and began on 2011-Nov-03 at 5:05:57 UTC.

Inspection of the new Chandra data (ObsID 12454) reveals the bright transient (which suffers from pile up) and over two dozen low-luminosity X-ray sources that are also seen in a deeper Chandra observation (ObsID 3798) from 2003 (Heinke et al. 2006, ApJ, 651, 1098). The positions are in good agreement and allow us to identify the transient currently in outburst as CXOGlb J174805.2-244647 (CX3 in Heinke et al. 2006) at J2000 coordinates 17:48:05.236 (0.002), -24:46:47.38 (0.02) from their Table 1. This is the same source that was in outburst in 2000, which was assumed to be EXO 1745-245.

This is in agreement with the analysis in ATel #3720, which strongly suggested the currently active source is CXOGlb J174805.2-244647.

We thank Harvey Tananbaum and the entire Chandra staff for their help in executing this observation.