[AAVSO-HEN] Swift-BAT discovery of hard x-ray transient SWIFT J1626.6-5156

[grb at aavso.org]

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TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4361
SUBJECT: Swift-BAT discovery of hard x-ray transient SWIFT J1626.6-5156
DATE:    05/12/18 19:55:18 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <Scott at lheamail.gsfc.nasa.gov>

H. Krimm (GSFC/USRA), S. Barthelmy (GSFC), M. Capalbi (ASDC), N. Gehrels (GSFC),
C. Gronwall (PSU), D. Palmer (LANL)
on behalf of the Swift team:

At 19:06:48 UT, Swift-BAT triggered and located a hard x-ray transient
which we name SWIFT J1626.6-5156 (trigger=173321).  The spacecraft did not slew
because of the Sun observing constraint (Sun distance 32 deg).
The BAT on-board calculated location is RA,Dec 246.657d,-51.937d
{16h 26m 38s,-51d 56' 13"} (J2000), with an uncertainty of 3 arcmin
(radius, 90% containment, stat+sys).

We note that (a) this is close to the galactic center (lon=333, lat=-2),
(b) the image significance is a strong 8.2 sigma, and (c) BAT has detected
emission from this location multiple times within the last 24 hours. 
We therefore conclude that this is a hard x-ray transient, and not a GRB.
The full Malindi data set in ~5 hours will likely provide the final determination
of the nature of this event.