INTEGRAL detection of a bright X-ray transient in Terzan 1 and a flare from IGR J17407-2808

ATel #13630; I. Mereminskiy (1), A. Lutovinov (1), R. Sunyaev (1, 2), S. Grebenev (1), R. Krivonos (1), S. Molkov (1) (1: IKI RAS, Moscow, Russia, 2: MPA, Garching, Germany)
on 13 Apr 2020; 13:21 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Ilya Mereminskiy (i.a.mereminskiy@gmail.com)

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During observations of the Galactic Center region performed on April 12, INTEGRAL/JEM-X detected an X-ray transient source at the position of RA, Dec = 263.9506, -30.4824 (J2000, 68% uncertainty radius is about 1').

This position is close to the center of well known globular cluster Terzan 1 and is only 17" off the position of historical LMXB XB 1732-30 (= 1RXS J173546.9-302859). Previously, X-ray activity from this position was observed by MAXI in 2013 (ATel #5096). The source is detected both in 3-12 keV band with the flux of 25±2 mCrab and in hard X-rays by INTEGRAL/IBIS with the flux of 43±4 mCrab in the 30-60 keV band.

Follow-up X-ray observations are essential for the final identification of this source.

Also, during the same observations we detected a bright, short flare from a fast X-ray transient IGR J17407-2808 (see discussion on its nature in Romano et al., 2016). Its duration was about 100 s with the mean flux of 300±30 mCrab in the 3-12 keV band. This flare could indicate a renewed activity of the source.