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INTEGRAL discovery of a possible new source IGR J18410-0535

ATel #340; J. Rodriguez (CEA, Saclay & ISDC Versoix), A. Domingo Garau (LAEFF, Vilspa), S. Grebenev (IKI, Moscow), A. Parmard (ESTEC, Noordwijk), J.-P. Roques (CESR, Toulouse), V. Schonfelder (MPE, Garching), P. Ubertini (IASF, Roma), R. Walter (ISDC, Versoix), N.-J. Westergaard (DSRI, Copenhagen)
on 8 Oct 2004; 16:18 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Jerome Rodriguez (jrodriguez@cea.fr)

Subjects: X-ray, Gamma Ray, Request for Observations, Binary, Black Hole, Neutron Star, Transient, Pulsar

Referred to by ATel #: 341

We report on the detection of a possible new source with the IBIS/ISGRI detector aboard the INTEGRAL observatory. The source, IGR J18410-0535, was discovered during Galactic Plane Deep Exposure, on October 8 2004 ~7h50 UTC, as it was undergoing a ~70 mCrab flare (integrated over 1700 s) in the 20-60 keV energy range, and 20 mCrab in the 60-200 keV range. The source was also detected in two subsequent INTEGRAL pointings, although only between 20 and 60 kev with a flux roughly half that of the peak one. The best position obtained with ISGRI is RA = 18h 41.0m, DEC.= 05deg 35 arcmin (+- 2 arcmin at 90%).

Analysis of the brightest pointing on smaller time scale (100 s time resolution) showed an increase of the flux by a factor of ~3 between two successive bins, up to 100 mCrab (20-60 keV) at maximum, over a period of about 600 s. The source flux then decayed to a level of ~40 mCrab.

We point out that this source is close (~7 arcmin) to the faint INTEGRAL source IGR J18406-0539 (Molkov et al. 2004 Astron. Letters/ astro-ph 0402416), and we therefore do not exclude the possibility that both sources are the same. Further observations are strongly needed especially to disentangle this last possibility.