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GCN Circular 15982

GRB 140311C: Swift-XRT and UVOT observations
2014-03-13T18:05:25Z (10 years ago)
Valerio D'Elia at ASDC <>
V. D'Elia (ASDC), L.M.Z. Hagen (PSU), L. Izzo (URoma/ICRA), P.  
D'Avanzo (INAF-OAB), S. Holland (STScI) report on behalf of the Swift  

We report on Swift observations of the field of the GBM discovered  
GRB140311C burst (Stanbro, GCN Circ 15977), for which a possible  
optical counterpart was reported by iPTF (Singer et al., GCN Circ  

XRT began observing the field on 2014-03-12 at 23:43:48 UT, i.e., �118  
ks after the trigger, for a total of 2.7ks. No source is detected at  
the iPTF coordinates, nor in the whole XRT field of view. The 3-sigma  
upper limit on the count rate is 5E-03 cts/s.

The Swift/UVOT began settled observations of the field of GRB 140311C  
118480 s after the trigger. No optical afterglow consistent with the  
iPTF position (Singer et al., GCN Circ. 15971) is detected in the  
initial UVOT exposure. The preliminary 3-sigma upper limit using the  
UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358,  
373) for the initial exposures are:

Filter�������� T_start(s)�� T_stop(s)����� Exp(s)�������� Mag
u�������������� 118480������ 125414�������� 2916������� >21.43

The magnitude in the table is not corrected for the Galactic  
extinction due to the reddening of E(B-V) = 0.01 in the direction of  
the burst (Schlegel et al. 1998).� We note that the photometry may be  
affected by a nearby bright foreground star.

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