GCN Circular 3364

D. Hullinger (UMD),  L. Barbier (GSFC), S. Barthelmy (GSFC),
L. Cominsky (Sonoma State), J. Cummings (GSFC/NRC),
E. Fenimore (LANL), R. Fink (GSFC), M. Galassi (LANL),
N. Gehrels (GSFC), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), D. Palmer (LANL),
A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS),
M. Suzuki (Saitama), M. Tashiro (Saitama U.), J. Tueller (GSFC),

on behalf of the Swift/BAT team:

At 23:22:21 UT, the Swift Burst Alert Telescope (BAT) triggered
and located GRB050505 (trigger=117504) (GCN Circ 3360, Hurkett
et al.).  The refined BAT ground position is (RA,Dec) = 141.787,
+30.245, [deg; J2000] +- 3 arcmin, (95% containment). The burst
was 49 degrees off the Swift boresight, which is ~30% coded.

The BAT mask-weighted light curve shows a multi-peaked
structure with a total duration T90 (15-350 keV) 60 +- 2 seconds
(estimated error including systematics).  The initial peak began
~15 seconds before the trigger and extended to 10 seconds after
the trigger.  There were three further short peaks beginning at
T+20 seconds, T+31 seconds, and T+49 seconds.

The spectrum is well fit by a simple power law with photon index
of 1.5 +- 0.1.  The fluence in the 15-350 keV band is
(4.1 +- 0.4) x 10^-6 erg/cm2.  The 1-second peak photon flux in
the 15-350 band is (2.2 +- 0.3) ph/cm2/s recorded at 1 second
after the trigger. All the quoted errors are at the 90% confidence level.

We note that this burst appears to be well-suited for ground
follow-up observations, as it is located 90 degrees from the Sun,
120 degrees from the Moon, close to the ecliptic, and away from
the Galactic plane.