INTEGRAL observation of IGR J17269-4737 / XTE J1727-476
ATel #631; M. Turler, S. Paltani, N. Mowlavi (ISDC, Geneva)
on 16 Oct 2005; 13:49 UT
Credential Certification: Nami Mowlavi (Nami.Mowlavi@obs.unige.ch)
Subjects: X-ray, Gamma Ray, Transient
Referred to by ATel #: 632
On October 15th at 12:18 UT INTEGRAL started a 50 ks TOO observation of IGR J17269-4737/XTE J1727-476 co-discovered one week ago by RXTE and INTEGRAL (ATels #623 and #624, respectively). The source is well detected by JEM-X in the 3-10 keV mosaic image (around 15 mCrab); it is not detected by JEM-X above 10 keV, neither by IBIS/ISGRI above 20 keV (3-sigma upper limit of 4 mCrab in the 20-40 keV mosaic image).
A preliminary spectral analysis of the JEM-X data gives a very soft spectrum in the 3-10 keV range. A good fit is obtained with a blackbody model with kT=0.37+/-0.02 keV (reduced chi2 of 1.4), leading to a 3-10 keV flux of 2x10^-10 ergs/sec/cm^2. An equally good fit is obtained with a thermal bremsstrahlung model with kT=0.55+/-0.03 keV, giving a 3-10 keV flux similar to that obtained in the BB model. In both models, N_H is fixed to its galactic value of 3.0 10^21 cm^-2.
The temperature of the bremsstrahlung model is about 3 times less than that derived on Oct.12 from SWIFT/XRT data (ATEL #626). However, the flux integrated in this model between 0.2 and 10 keV has only decreased by 25%. Follow-up observations are encouraged.
