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Discovery of kilohertz quasi-periodic oscillations from EXO 1745-248

ATEL # 2935; Arunava Mukherjee (TIFR), Sudip Bhattacharyya (TIFR)
on 14 Oct 2010; 14:55 UT
Password Certification: Sudip Bhattacharyya (

Subjects: X-ray, Request for Observations, Binaries, Globular Clusters, Neutron Stars, Pulsars, Transients
Referred to by ATEL #: 2939, 3000, 3044

The current outburst (ATEL #2919) of a transient X-ray source in Terzan 5, which is plausibly EXO 1745-248 (ATEL #2920; but see ATEL #2933), provides motivation for archival data analysis of EXO 1745-248. In the archival RXTE PCA data of 2000-09-30 (T15:29:24 to T16:24:09; ObsId 50054-06-11-00), an extremely strong kHz QPO at ~690+-23 Hz with a fractional rms amplitude of ~0.08 has been detected. To the best of our knowledge, this is the first high frequency feature detected from EXO 1745-248. Its single trial significance is ~1.86e-96, and a conservative final significance is ~1.11e-89. The QPO profile has prominent sub-features. Currently, about 150 ks of PCA archival data of EXO 1745-248 is available, and more observations of Terzan 5 with RXTE are strongly encouraged.

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R. E. Rutledge , Editor
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