Skip to main content
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 15182

Swift follow-up results of the possible weak INTEGRAL GRB
2013-09-06T14:01:35Z (11 years ago)
Rhaana Starling at U of Leicester <>
Rhaana Starling (U. Leicester) reports on behalf of the Swift team

We report further analysis of Swift follow-up of the possible weak INTEGRAL GRB detected on 4th September 2013 (GCN 15180).
The full XRT dataset, comprising 6.28 ks of exposure and beginning 2 hours after the INTEGRAL detection, shows no evidence for
a source at the INTEGRAL Weak alert position. The 3-sigma upper limit on the count rate at this position, using Bayesian statistics
(Kraft, Burrows & Nousek 1991), is 2.2e-3 count/s.

We do find a new X-ray source at position
RA  (J2000) =  17 08 03.52
Dec (J2000) = -32 02 31.5
or RA, Dec = 257.0147, -32.0421 degrees
with an uncertainty of 3.9 arcseconds (radius, 90% confidence). This is 7.3 arcminutes from the INTEGRAL position, and lies
outside the given 3.6 arcminute radius error circle.
This source is 4.9-sigma significant, and has a count rate of (4.4 +3.6/-2.5)e-3 count/s. A source is listed at this position in a
number of optical and nIR surveys, and in the Atlas of Radio/X-ray associations (Flesch 2010) where it is classified as a double
radio lobe.
Three further low-significance (=<3-sigma) sources are present in the field.
The association of any of these with the INTEGRAL trigger is unclear.

No further Swift observations of this source are planned at this time.
Looking for U.S. government information and services? Visit