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Swift follow-up observations of IGR J16374-5043

ATEL # 2810; E. Bozzo, C. Ferrigno, L. Pavan (ISDC, University of Geneva)
on 24 Aug 2010; 11:05 UT
Distributed as an Instant Email Notice (Transients)
Password Certification: E. Bozzo (

Subjects: X-ray, Transients

Following the discovery of the new transient source IGR J16374-5043 with INTEGRAL (Atel #2809), two follow-up observations with Swift/XRT were carried out on 2010 August 23 and 24. The first observation lasted only for 150 s due to the occurrence of the GRB 100823A. The total exposure time of the second observation was 1.7 ks.

In both observations a very faint X-ray source is visible within the ISGRI error circle (2 arcmin). We summed up the two pointings in order to improve the S/N of the detection.

The best determined source position is at RA: 16:37:13.5, DEC: -50:43:29.3 (J2000), with an associated error of 4.7 arcsec (S/N=5.6). The estimated source count rate in the 0.3-10 keV energy band is (3.1+/-0.5)E-02 cts/sec.

Assuming an absorbed power-law model for the source spectral emission with Gamma=2 (see Atel #2809) and N_H=0.86E22 cm^(-2) (as expected in the direction of the source), the above count rate would translate in a X-ray flux of 1.4E-12 ergs/cm^2/s (2-10 keV). This relatively low X-ray flux is consistent with the rapid fading of the source observed after the burst detected by INTEGRAL on 2010 August 22 at 00:40.

We thanks the Swift team for their support and the very rapid scheduling of the observation of IGR J16374-5043.

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R. E. Rutledge , Editor
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