TITLE:   GCN CIRCULAR
NUMBER:  15110
SUBJECT: GRB 130816B: Swift/UVOT Upper Limits 
DATE:    13/08/19 19:48:10 GMT
FROM:    Stephen Holland at STScI  <sholland@stsci.edu>

S. T. Holland (STScI) and M. Stamatikos (OSU/NASA/GSFC)
report on behalf of the Swift/UVOT team:

     The Swift/UVOT began settled observations of the field of GRB
130816B starting 75 s after the BAT trigger (Stamatikos et al. 2013,
GCNC 15099).  We do not detect any new source consistent with the
GROND afterglow position (Varela et al. 2013, GCNC 15107) in any of
the UVOT exposures.  Preliminary 3-sigma upper limits using the UVOT
photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373)
for the finding chart (FC) exposures and initial summed exposures are
presented below.

---------------------------------------------------
Filter       TSTART      TSTOP    Exposure      Mag
---------------------------------------------------
white (FC)       75        225         147    >20.7
    u (FC)      287        537         246    >19.9
---------------------------------------------------
    v           618     12,639        1295    >20.4
    b           543       7299         530    >20.7
    u           692     19,298         923    >20.5
 uvw1           667     18,676        1238    >20.8
 uvm2           642     13,534        1227    >20.8
 uvw2           593     24,128         882    >20.7
white           567       7498         672    >21.5
---------------------------------------------------

     The quoted upper limits have not been corrected for the expected
extinction due to the Galactic reddening along the line of sight to
this burst of E(B-V) = 0.50 mag (Schlafly et al. 2011, ApJS, 737,
103).  GRB 130816B was 3 degrees above the Galactic Plane, so this
extinction value is highly uncertain.