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Seyfert 2 VV 780 detected with INTEGRAL

ATel #410; Emrah Kalemci (SSL/UCB), Steven E. Boggs (SSL/UCB), Niels Lund (DNSC)
on 15 Feb 2005; 18:05 UT
Credential Certification: Emrah Kalemci (emrahk@mamacass.ucsd.edu)

Subjects: X-ray, Gamma Ray, Request for Observations, AGN, Black Hole

The analysis of the ISGRI / INTEGRAL data of SN 1006 observations yielded an unknown catalog source located at RA=14h57m31s, DEC=-43d10m11s. The source is detected with 8.7 sigma in 20-40 keV band in the mosaic image covering all SN 1006 observations taken in Jan 2004, revolutions 155, 156, 157 and 158 with ~700 ks of data. Subsequent investigation revealed that the Seyfert 2 galaxy VV 780 is in the error circle of ISGRI for the source position.

The ISGRI spectrum obtained using the mosaic image can be fitted with a power law of index 2.2 +- 0.4 and the 20-50 keV flux is 8.8 10^-12 ergs cm^-2 s^-1.

The source was not detected with JEM-X (0.06 mCrab upper limit in 4.2-8.4 keV band), and Seyfert 2s are known to be highly obscured. There is no X-ray source in the ROSAT catalogue within the ISGRI error circle. The SN 1006 observations taken on January 2003 in revolutions 30 and 32 did not show an excess in the ISGRI image at the source position, pointing to variable emission. The 2 sigma upper limit flux in 20 - 50 keV band for these observations is 10^-11 ergs cm^-2 s^-1. The analysis of other public INTEGRAL observations of the source position is underway. As best of our knowledge, this area of the sky has not been observed with modern X-ray satellites, and this is the first detection of the source in hard X-rays. Further observations with other instruments and analysis of the INTEGRAL data will shed light to the nature of variability of this object in X-rays.