Serendipitous detection of an X-ray transient (possibly 2E 1050.8-6200) in the Galactic plane with INTEGRAL/JEM-X

Gaurava K. Jaisawal*, Jérôme Chenevez

*Corresponding author for this work

Research output: Other contributionNet publication - Internet publicationResearch


During INTEGRAL observations of the Galactic Plane (PI: A. Bazzano), carried out between 2022-09-16T21:18 and 2022-09-17T05:49 (revolution 2549) for 26.5 ks, a target was clearly detected at the location RA=10:52:45 and DEC=-62:15:32 (J2000) in the INTEGRAL/JEM-X field of view. This position coincides with the X-ray source 2E 1050.8-6200 within a search radius of 90 arcseconds. Only two other known optical sources i.e. AST18432 (an eclipsing binary) and the star HD 308041 are found in the search radius.

The source is well detected in two energy bands with the following average fluxes: 7.5+/-1 mCrab (approx. 1.1 × 10-10 erg/s/cm2) in 3-10 keV and 14+/-4 mCrab (approx. 7.9 × 10-11 erg/s/cm2) in 10-25 keV. The JEM-X light curve does not show any particular activity.

The observed X-ray emission from 2E 1050.8-6200, makes it an interesting source of study due to its rare detection with any X-ray instruments. Historically, the X-ray source was discovered by the Imaging Proportional counter aboard the EINSTEIN satellite (HEAO 2) between 1978 and 1981 (2E catalogue; Harris et al. 1994), and by the Wide Field Cameras onboard BeppoSAX between 1996 and 2002 (BeppoSAX/WFC X-ray source catalogue; Verrecchia et al. 2007). In the WFC catalogue, 2E 1050.8-6200 was observed at a flux level of 1.76 × 10-10 erg/s/cm2in 2-10 keV band. Our reported flux value is similar to the one measured with the WFC.

The last time the source position was covered by the JEM-X field of view was during INTEGRAL revolution 2513 on 2022-06-11. The source was then not detected with a total effective exposure of 18 ks, leading to a 3-\sigma upper limit of about 4 mCrab (3-10 keV).

Multi-wavelength observations are encouraged to follow-up the new activity of this old transient source.


Harris D. E. et al. 1996, VizieR Online Data Catalog, IX/013

Verrecchi F. et al. 2007, A&A, 472, 705
Original languageEnglish
Publication date23 Sept 2022
Publication statusPublished - 23 Sept 2022
SeriesThe Astronomer's telegram


  • X-ray
  • Transient


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