INTEGRAL detects the recurrent transients XTE J1709-267 and XTE J1739-285 in outburst
ATel #4304; C. Sanchez-Fernandez (ESA/ESAC, Spain), J. Chenevez (DTU Space, Denmark), L. Pavan, E. Bozzo (ISDC, Switzerland), M. Cadolle Bel (ESA/ESAC, Spain), L. Natalucci (INAF-IASF, Italy), L. Sidoli (INAF-IASF, Italy) K. Watanabe (FGCU, USA)
on 10 Aug 2012; 21:56 UT
Credential Certification: Celia Sanchez-Fernandez (email@example.com)
Subjects: X-ray, Binary, Transient
The neutron star, recurrent X-ray transients XTE J1709-267 (=RX J1709.5-2639) and XTE J1739-285, both of which are known X-ray bursters, were detected in outburst during INTEGRAL observations of the Galactic Center region (PI, J. Wilms), carried out between (UT) 2012 August 08, 07:18 - 19:05.
XTE J1709-267 was seen by JEM-X at the 54-sigma level in the 3-10 keV band, with an average flux of 141 +/- 3 mCrab, and at the 27-sigma level in the 10-25 keV band, with an average flux of 61 +/- 7 mCrab. The effective JEM-X exposure time was 4 ks. XTE J1709-267 was only marginally detected by ISGRI in the 20-40 keV band. We estimate a rough flux of ~8 mCrab (5 sigma) for an effective ISGRI exposure time of 21 ks. A preliminary spectral fit to the JEM-X data is consistent with an absorbed disk blackbody model of temperature ~2.2 keV. The onset of this outburst was also detected by MAXI http://maxi.riken.jp/top/index.php?cid=1&jname=J1709-266
This new outburst from XTE J1709-267 occurs 2 years after the previous period of activity of the source, reported by MAXI/GSC (ATEL #2729), and is consistent with a outburst recurrence time of 2-3 years, claimed in ATel #1302.
XTE J1739-285 was seen by JEM-X at the 9-sigma level in the 3-10 keV band, with an average flux of 16 +/- 2 mCrab, and at the 8-sigma level in the 10-25 keV band, with an average flux of 16 +/- 4 mCrab, for an effective exposure time of 10 ks. A weak (short) type-I X-ray burst was detected during these observations. The source flux in the 20-40 keV band was below the ISGRI sensitivity limit.
The last outburst from XTE J1739-285, reported by INTEGRAL (ATel #734) was detected in 2006.
XTE J1709-267 and XTE J1739-285 will be observed regularly by INTEGRAL in the coming weeks during Galactic Center and Galactic Bulge monitoring observations.