TITLE:   GCN CIRCULAR
NUMBER:  14086
SUBJECT: GRB 121209A: Swift/UVOT Upper Limits
DATE:    12/12/14 17:19:02 GMT
FROM:    Stefan Immler at NASA/GSFC  <stefan.m.immler@nasa.gov>

S. Immler (NASA/CRESST/GSFC) and A. Maselli (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 121209A
96 s after the BAT trigger (Maselli et al., GCN Circ. 14045).
No optical afterglow consistent with the optical position (Kruehler
et al. GCN Circ. 14049) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC            96          246          147         >21.4
white               96        12808         1217         >21.7
v                 5857        35749         1967         >20.3
b                 5241        24926         1784         >21.1
u                  308        30697         1959         >21.6
w1                6267        29936         1968         >21.5
m2                6062        36468         2314         >22.3
w2                5652        34835         1968         >21.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.05 in the direction of the burst
(Schlegel et al. 1998).