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Chandra ToO Observation of SGR 1627-41

ATEL # 1564; Peter M. Woods (Dynetics/NSSTC), Chryssa Kouveliotou (MSFC/NSSTC), Ersin Gogus (Sabanci Univ), and Kevin Hurley (Univ of California - Berkeley)
on 6 Jun 2008; 19:15 UT
Password Certification: Peter Woods (Peter.Woods@dynetics.com)

Subjects: X-ray, Neutron Stars, Pulsars, Soft Gamma-ray Repeaters

A follow-up ToO observation of the burst active SGR 1627-41 (GCN #7777, ATEL #1548) with Chandra was carried out on 2008 June 3. The on-source exposure time for this observation was 40 ks during which the ACIS detectors recorded ~1100 counts from the SGR in CC mode. As noted by Esposito et al. (ATEL #1555), the source intensity had dropped significantly from the brightness level measured directly after the burst activity began on 2008 May 28. The 2-10 keV flux during the Chandra observation was 1.210-12 erg cm-2 s-1. The energy spectrum was well fit by a power law with a photon index Gamma = 1.30+0.58-0.17 and column density NH = 10.9+2.8-0.8 1022 cm-2 (1-sigma confidence).

No pulsations were detected from the SGR during this Chandra observation. Due to the low flux level, the upper limit on coherent pulsations was not very constraining. Specifically, we place an upper limit to the rms pulsed fraction of SGR 1627-41 at 33% during this observation for sinusoidal pulsations within the frequency range 110-4 - 17 Hz (99% confidence).

We thank Andrea Prestwich and the rest of the Chandra team for approving and executing this ToO.


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