TITLE:   GCN CIRCULAR
NUMBER:  13791
SUBJECT: GRB 120919A: Swift/UVOT Upper Limits
DATE:    12/09/21 13:24:16 GMT
FROM:    Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>

S.R. Oates (MSSL-UCL) reports on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 120919A
134 ks after the IPN trigger (Hurley et al. GCN Circ. 13786)
No optical afterglow is found within the IPN error box nor 
at the location of the two uncatalogued XRT sources (Beardmore et al. GCN Circ. 13790). 
We note the presence of a catalogued USNO-B1 source within 4.5" of XRT source 1,
with a m2 magnitude 20.52 +\- 0.17.

Preliminary 3-sigma upper limits 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

m2              133695       157598         4891         >21.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.10 in the direction of the burst
(Schlegel et al. 1998).