Konus-Wind observations of Galactic transient GRS 1915+105 in outburst

ATel #12818; D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova (Ioffe Institute), and T. Cline
on 29 May 2019; 19:09 UT
Credential Certification: Anna Kozlova (ann_kozlova@mail.ioffe.ru)

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Between May 14 and 27, 2019 Konus-Wind (KW) detected multiple hard X-ray bursts with durations from a few hundreds to a few thousands of seconds. Taking into account the proximity of some of these bursts to the MAXI/GSC triggers due to GRS 1915+105 (ATel #12761 and ATel #12787), and flares from the same source observed by Astrosat/SXT (ATel #12805); and consistency of the KW ecliptic latitude response with the position of GRS 1915+105, we suggest that the flaring activity observed by KW is due to GRS 1915+105.

The KW light curve recorded in the waiting mode shows well separated flares along with flare clusters containing more than a dozen episodes

 
Date        Tstart(UT)  Tstart(MJD)  Duration(ks) 
2019-05-14  14:15       58617.594    ~610 
2019-05-20  17:20       58623.722    ~25 
2019-05-21  12:20       58624.514    ~22 

A single ~20 ks long, bright flare was observed at about 2019-05-26 16:40 UT (MJD 58629.694). The emission is visible in the instrument's G1 (20-80 keV) and G2 (80-300 keV) bands.

The KW light curves of the clusters and the flare are provided in the link below.

Further KW observations of the activity of the source will be reported. All the presented results are preliminary.

Konus-Wind is a gamma-ray spectrometer operating onboard the NASA GGS-WIND spacecraft since November 1994. It contains two NaI scintillation detectors continuously observing the whole sky and covers the energy band from ~20 keV to ~15 MeV.

GRS 1915+105 Konus-Wind waiting mode lightcurve