[vsnet-grb-info 16129] GRB 150204A: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17411
SUBJECT: GRB 150204A: Swift/UVOT Upper Limits
DATE:    15/02/05 16:42:34 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld at ucl.ac.uk>

A. Breeveld (MSSL-UCL), D. Malesani (DARK/NBI) and B. Sbarufatti 
(INAF-OAB/PSU) report on behalf of the Swift/UVOT team:

The Swift/UVOT observed the field of GRB 150204A during follow-up 
observations, 51182 s after the BAT trigger (Cummings et al. GCN Circ. 
17404). No optical afterglow consistent with the possible XRT 
counterpart (A. Melandri et al. GCN Circ. 17409) 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 initial 
exposures are:

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

v                57368        58276          885         >19.5
u                52088        52670          568         >19.5
w1               51182        63642         1495         >20.3
m2               58281        63016         1027         >20.1
w2               56461        57361          886         >19.9

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.824 in the direction of 
the burst (Schlegel et al. 1998).