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GCN Circular 18571

Subject
GRB 151107A: Further investigation of the source nature
Date
2015-11-09T22:06:51Z (9 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), and D. M. Palmer (LANL) report on behalf of 
the Swift-BAT team:

We perform further investigation regarding the uncertainty of the source nature 
of GRB151107A (Lien et al., GCN Circ. 18564) due to its proximity to the 
Galactic plane (within 1 deg) and the featureless light curve.

Using analysis from the BAT transient monitor (Krimm et al., 2013), there is 
no significant emission in the 15-50 keV band at ~ 4000 s before and ~ 6000 s
after the event data (signal-to-noise ratio < 1.8 sigma). The source was out of 
the field of view for the immediate time outside the event data range due to
pre-planned telescope slews. A search in the daily mosaic images at the burst 
location shows a 4-sigma detection on Nov. 7 (12.5 mCrab) and 1.6 sigma on 
Nov. 8 (which corresponds to a 1-sigma upper limit of ~ 5 mCrab).

This flux level and time profile are consistent with a GRB, and appear dimmer 
and shorter than a usual accreting binary source during outburst. However, 
we cannot rule out other possible Galactic transients, such as thermonuclear 
bursts or flaring stars.

In addition, we note that within 20.3 arcsec of the revised BAT position is the 
bright M2/M3 type star designated HD 126577. It is possible that the BAT 
detections correspond to a flaring episode from HD 126577, although this 
star is not known for such episodes.
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