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1A 1118-61: detection of the pulsation period in Swift-XRT data

ATel #1896; Vanessa Mangano (INAF-IASF PA)
on 9 Jan 2009; 15:32 UT
Credential Certification: Vanessa Mangano (vanessa@ifc.inaf.it)

Subjects: X-ray, Binary, Neutron Star, Transient, Pulsar

Referred to by ATel #: 1949

The Be/X-ray transient 1A 1118-61 triggered Swift on 2009 January 4 at 03:52:35.6 UT (Mangano et al., GCN Circ. #8777) and at 13:37:39.6 UT. The source was monitored by XRT for 4 days, and a total exposure of 26 ks of data were collected (17 ks in Windowed Timing mode and 9 ks in Photon Counting mode). The light curve is highly variable.
We performed a temporal analysis with epoch folding search techniques around the expected pulsation period of 405 s (Nagase F. 1989, Publ. Astron. Soc. Jap., 41, 1-79) and detected a highly significant pulsation at 407.68 +/- 0.02 s. The folded light curve shows a complex structure with three main sub-peaks. Further analysis is ongoing.