During the INTEGRAL observations of GRS1915+105, performed from 2010 October 28 at 18:25 to 2010 October 29 at 00:10 UTC (total exposure time ~20 ks), IBIS/ISGRI detected a renewed activity from the transient binary system IGR J19294+1816. The nature of the source is still debated, and it is classified as a possible Be binary system or supergiant fast X-ray transient (SFXT, Rodriguez et al. 2009, A&A, 508, 889).
During the latest INTEGRAL observations, the source is detected in the IBIS/ISGRI mosaic at a significance level of 30 sigma (20-40 keV). Its spectrum is best fit with a blackbody model of kT=4.8+/-0.4 keV (effective exposure time 13 ks). The estimated flux in the 20-40 keV energy band is (4.9+/-0.3)E-10 erg/cm^2/s (uncertainties at 90% c.l.).
The source was outside the JEM-X FOV during the entire observational period.
Previous INTEGRAL observations in the direction of IGR J19294+1816 were performed from 2010 October 22 at 23:04 to 2010 October 23 at 05:31, for a total exposure time of 20 ks. In that occasion IGR J19294+1816 was not detected in the IBIS/ISGRI FOV and we estimated a 3 sigma c.l. upper limit on the hard X-ray flux from the source of 5.6 mCrab, corresponding to ~4.3E-11 erg/cm^2/s.
We encourage observations at other wavelengths to characterize the nature of this interesting transient source.
|Publication date||29 May 2012|
|Publication status||Published - 29 May 2012|
|Series||The Astronomer's telegram|
- Gamma ray