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INTEGRAL observations of the magnetar CXOU J164710.2-455216/PSR J1647-4552 in outburst

ATel #11270; V. Savchenko, C. Ferrigno, E. Bozzo (ISDC, University of Geneva, Switzerland),S. Mereghetti (IASF-MI/INAF, Italy), D. Goetz (CeA Saclay, France), L. Ducci (IAAT Tuebingen, Germany)
on 7 Feb 2018; 16:15 UT
Credential Certification: Carlo Ferrigno (Carlo.Ferrigno@unige.ch)

Subjects: X-ray, Gamma Ray, Neutron Star, Magnetar

The INTEGRAL Bust Alert System (IBAS) detected two short bursts in the IBIS/ISGRI data at 2018-02-06 07:25:58.47 (trigger ID 8007) 2018-02-06 12:33:36.17 (trigger ID 8008). The localization of these bursts is known within three arcminutes and compatible with the magnetar CXOU J164710.2-455216/PSR J1647-4552 location. This source was reported to be active by Swift/BAT, Swift/XRT, and Fermi/GBM (GCN #22389, ATel #11264, GCN #22402).

INTEGRAL serendipitously observed PSR J1647-4552 from 2018-02-03 14:02:05 to 2018-02-04 12:14:00, and from 2018-02-05 21:09:14 to 2018-02-06 12:13:46, during the observation of the Muscae Region (PI A. Bazzano) for a total on-source time of 141 ks. In the IBIS/ISGRI data, we found three bursts with S/N above 4.5 on 50 ms, 100 ms, and 500 ms time scales; including the two reported by IBAS:
Time
UTC
Fluence
(erg cm-2 in 25-80 keV)
2018-02-06 00:33:19 1.7±0.4 × 10-8
2018-02-06 07:25:56 2.0±0.5 ×10-8
2018-02-06 12:33:34 2.5±0.6×10-8
In the complete mosaicked images of ISGRI and JEM-X data, we do not detect the source. We set an upper limit (5 σ confidence level) on the average persistent flux of 3.1e-11 erg/s/cm2 in the 20 - 40 keV IBIS/ISGRI band and 2.6e-10 erg/s/cm2 (effective exposure 17 ks) in the 3 - 10 keV JEM-X band (effective exposure 13 ks). This is consistent with the Swift/XRT fluxes reported in ATel #11264. The source is not detected on a timescale of individual INTEGRAL pointings (about 1 hour), with a typical 5-sigma upper limit of 2.6e-10 erg/s/cm2(20 - 40 keV).

INTEGRAL target of opportunity observations have been scheduled and coordinated observation are encouraged.