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A quick outburst decay from IGRJ19566+326

ATel #7520; S. V.Molkov (IKI, Moscow), A. A.Lutovinov (IKI, Moscow), K. A.Postnov (SAI MSU, Moscow), A. M.Cherepashchuk (SAI MSU, Moscow)
on 17 May 2015; 12:46 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Alexander Lutovinov (aal@hea.iki.rssi.ru)

Subjects: X-ray, Transient

Referred to by ATel #: 7524, 8143, 9565

We report the preliminary results of the monitoring campaign of newly discovered hard X-ray transient IGRJ19566+0326 (Atel #7506) performed with the XRT telescope on board the Swift observatory.

The source was first detected in the 0.5-2 keV energy band during the ~3ks XRT observations in 13/05/2015 (started around 23:05 UT) at the flux level (5.8+/-0.2)e-12 erg/s/cm2. Next two XRT observations showed a rapid time decay of the source flux: (1.44+/-0.2)e-12 erg/s/cm2 in 14/05/2015 (started around 10:22 UT, ~0.5ks exposure time) and (1.4+/-0.3)e-13 erg/s/cm2 in 15/05/2015 (started around 15:24 UT, ~2ks exposure). We estimate the logarithmic slope of the outburst time decay to be 0.3-0.4 days.

The 0.5-2 keV energy band was chosen as the reference one due to the non-detection of the source at energies >2 keV in later observations (probably due to a short exposure and insufficient sensitivity). The absorption column was fixed at 3.5e21 cm-2 as measured during the bright state of the source (Atel #7506).

We continue monitoring the source in X-rays as well as its observations in other wavebands.

We thank the Swift team for the quick responses on our requests and the organization of the follow-up observations.