[vsnet-grb-info 16621] Swift trigger 642453 is not an astrophysical source
GCN Circulars
gcncirc at capella2.gsfc.nasa.gov
Thu Jun 4 23:58:08 JST 2015
TITLE: GCN CIRCULAR
NUMBER: 17902
SUBJECT: Swift trigger 642453 is not an astrophysical source
DATE: 15/06/04 14:58:01 GMT
FROM: Valerio D'Elia at ASDC <delia at asdc.asi.it>
V. D'Elia (ASDC), S. D. Barthelmy (GSFC), P. A. Evans (U. Leicester),
L. Izzo (URoma/ICRA) and M. H. Siegel (PSU) report on behalf of the
Swift team:
We have analysed 4.5 ks of Swift/XRT data for the Swift/BAT-detected
possible burst GRB 150604A (D'Elia et al. GCN Circ. 17901), collected
in Photon Counting mode, between 138 s and 21.6 ks after the BAT
trigger. No X-ray sources have been detected inside or close to the
Swift/BAT error region. The 3-sigma upper limit at the Swift/BAT
position is ~0.002 ct s^-1, corresponding to a 0.3-10 keV observed
flux of ~1e-13 erg cm^-2 s^-1 (assuming a typical GRB spectrum).
Ground analysis of the BAT data for this trigger shows that the
significance of the initial detection has dropped below that
considered to be a valid trigger.
Swift/UVOT began settled observation of the field 142 s after the BAT
trigger. No new source is detected in the initial 1.4 ks of
observation down to a white magnitude limit of 20.9.
Therefore, this trigger is likely due to noise, and not due to
anything astrophysical.
This circular is an official product of the Swift team.
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